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CHEMISTRY, M3 EQ-Bank 6 MC

Which of the following species decreases in oxidation number?

\(\ce{Fe^{2+}(aq) + MnO4^-(aq) + 8H^+(aq) -> 5Fe^{3+} + Mn^{2+}(aq) + 4H2O(l)}\)

  1. \(\ce{Fe^{2+}(aq)}\)
  3. \(\ce{H2O(l)}\)
  4. \(\ce{H^+(aq)}\)
Show Answers Only

\(B\)

Show Worked Solution

→ The oxidation number of  \(\ce{Fe^{2+}(aq)}\)  increases from +2 to +3.

→ The oxidation number of \(\ce{Mn}\) in \(\ce{MnO4^-}\) 

\(\ce{Mn} +4(-2)\) \(=-1\)  
\(\ce{Mn}\) \(=7\)  

 
→ \(\ce{Mn}\) decreases from an oxidation number of 7 to 2 during the reaction.

\(\Rightarrow B\)

CHEMISTRY, M3 EQ-Bank 4 MC

Which set of oxidation and reduction reactions would result in a spontaneous process?

\begin{align*}
\begin{array}{l}
\ & \\
\textbf{A.}\\
\textbf{B.}\\
\textbf{C.}\\
\textbf{D.}\\
\end{array}
\begin{array}{|c|c|}
\hline
\textit{Oxidation} & \textit{Reduction} \\
\hline
\ce{Mg(s) -> Mg^{2+}(aq) + 2e^-} & \ce{Cu^{2+}(aq) +2e^- -> Cu(s)} \\
\hline
\ce{Ag(s) -> Ag^+(aq) + e^-} & \ce{Fe^{3+}(aq) +e^- -> fe^{2+}} \\
\hline
\ce{Cu(s) -> Cu^{2+}(aq) + 2e^-} & \ce{Zn^{2+}(aq) +2e^- -> Zn(s)} \\
\hline
\ce{Pb^{2+}(aq) +2e^- -> Pb(s)} & \ce{Cu(s) -> Cu^{2+}(aq) + 2e^-} \\
\hline
\end{array}
\end{align*}

Show Answers Only

\(A\)

Show Worked Solution

→ For a redox reaction to be spontaneous, the cell potential must be a positive number.

→ Option A:  \(E^{\circ}_{\text{cell}} = 0.34-(-2.36) = 2.70\ \text{V}\)  → Spontaneous

→ Options B and C: both have negative cell potentials and will therefore be non-spontaneous.

→ Option D: has the reduction and oxidation equations around the wrong way, going against the natural direction for a spontaneous reaction.

\(\Rightarrow A\)

BIOLOGY, M4 EQ-Bank 8

A 3000 hectare koala sanctuary was created in 1980 and the koala population over the next 35 years was monitored and the data graphed below.
 

Identify and explain the ecological significance of the parts of the graph labelled A, B and C.   (5 marks)

Show Answers Only

Curve at point A:

→ The curve at point A shows exponential population growth.

→ The koala population is rapidly increasing due to abundant resources and minimal limiting factors, allowing for maximum reproductive success.
 

Curve at point B:

→ At point B the population growth begins to slow.

→ As the koala population grows, competition for resources like food and habitat increases.

→ While the population still grows, it does so with a decreasing population growth rate.
 

Curve at point C:

→ Point C shows the population reaching the sanctuary’s carrying capacity at around 1300 koalas.

→ The koala population has levelled off with births and deaths in balance.

→ At this stage, the environment is supporting the maximum sustainable number of individuals.

Show Worked Solution

Curve at point A:

→ The curve at point A shows exponential population growth.

→ The koala population is rapidly increasing due to abundant resources and minimal limiting factors, allowing for maximum reproductive success.
 

Curve at point B:

→ At point B the population growth begins to slow.

→ As the koala population grows, competition for resources like food and habitat increases.

→ While the population still grows, it does so with a decreasing population growth rate.
 

Curve at point C:

→ Point C shows the population reaching the sanctuary’s carrying capacity at around 1300 koalas.

→ The koala population has levelled off with births and deaths in balance.

→ At this stage, the environment is supporting the maximum sustainable number of individuals.

BIOLOGY, M2 EQ-Bank 17

The image below shows a dinosaur fossil found in South Africa believed to be 200 million years old.

  1. What type of diet did this dinosaur likely consume? Explain your answer.   (1 mark)
  2. Discuss two features that could be observed in the dinosaur’s digestive tract.   (3 marks)
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a.   Diet: herbivore

→ The presence of flat teeth in a dinosaur species strongly indicates a herbivorous diet, as these teeth are well-suited for grinding and processing plant material.
 

b.   Digestive tract features:

→ Herbivorous dinosaurs likely possessed specialised digestive tracts adapted for processing plant material.

→ One key feature would be an enlarged caecum, a pouch-like structure connected to the large intestine, which housed symbiotic bacteria to break down cellulose through fermentation. This process would have allowed dinosaurs to extract more nutrients from tough plant matter.

→ Additionally, these dinosaurs may have had elongated intestines to increase the surface area for nutrient absorption and provide more time for the digestion of fibrous plant material.

Show Worked Solution

a.   Diet: herbivore

→ The presence of flat teeth in a dinosaur species strongly indicates a herbivorous diet, as these teeth are well-suited for grinding and processing plant material.
 

b.   Digestive tract features:

→ Herbivorous dinosaurs likely possessed specialised digestive tracts adapted for processing plant material.

→ One key feature would be an enlarged caecum, a pouch-like structure connected to the large intestine, which housed symbiotic bacteria to break down cellulose through fermentation. This process would have allowed dinosaurs to extract more nutrients from tough plant matter.

→ Additionally, these dinosaurs may have had elongated intestines to increase the surface area for nutrient absorption and provide more time for the digestion of fibrous plant material.

CHEMISTRY, M3 EQ-Bank 8

A galvanic cell has been set up as illustrated in the diagram below.

  1. The standard potential for this reaction is 0.78 V. Use half equations to determine the unknown electrode.   (2 marks)
  1. The unknown solution is light green in colour. Explain what will happen to the colour of the unknown solution as the reaction proceeds.   (2 marks)
  1. After some time, a solid deposit formed on the copper electrode was removed and dried. The mass of the deposit was 0.150 g. Determine the final concentration of the copper nitrate solution.   (3 marks)
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a.    \(\ce{Fe(s) -> Fe^{2+} + 2e^-}\)

b.    As the reaction progresses:

→ The solution will darken, taking on a more intense green colour.

→ This change occurs because nickel undergoes oxidation to form \(\ce{Fe^{2+}}\) ions, which are released into the solution, thereby increasing its colour intensity.

c.    \(0.137\ \text{mol L}^{-1}\)

Show Worked Solution
a.     \(E^{\circ}_{\text{cell}}\) \(=E^{\circ}_{\text{cathode}}-E^{\circ}_{\text{anode}}\)
  \(0.78\) \(=0.34-E^{\circ}_{\text{anode}}\)
  \(E^{\circ}_{\text{anode}}\) \(=0.34-0.78\)
  \(E^{\circ}_{\text{anode}}\) \(=-0.44\)

 

→ \(\ce{Fe^{2+} + 2e^- -> Fe(s)} \qquad -0.44\ \text{V}\)

→ \(\ce{Fe^{2+}}\) is undergoing oxidation. The correct half equation is: \(\ce{Fe(s) -> Fe^{2+} + 2e^-}\)
 

b.    As the reaction progresses:

→ The solution will darken, taking on a more intense green colour.

→ This change occurs because nickel undergoes oxidation to form \(\ce{Fe^{2+}}\) ions, which are released into the solution, thereby increasing its colour intensity.
 

c.    Moles of solid copper formed on electrode: \(\dfrac{m}{MM}=\dfrac{0.175}{63.55}=2.36 \times 10^{-3}\ \text{mol}\)

Moles of copper taken out of solution: \(2.36 \times 10^{-3}\ \text{mol}\)

Moles of copper remaining in solution: \((0.15 \times 0.18)-2.36 \times 10^{-3}= 0.0246\ \text{mol}\)

Final concentration: \(c=\dfrac{n}{V}=\dfrac{0.0246}{0.18}=0.137\ \text{mol L}^{-1}\)

BIOLOGY, M4 EQ-Bank 2 MC

Which of the following relationships is an example of parasitism?

  1. A cleaner wrasse removing parasites from a larger fish.
  2. A lichen formed by a fungus and an alga growing together on a rock.
  3. An orchid growing on the branch of a rainforest tree without harming it.
  4. A cuckoo laying its eggs in another bird's nest for the host to raise.
Show Answers Only

\(D\)

Show Worked Solution

Option A is an example of mutualism (both benefit).

Option B describes mutualism in the form of a lichen. The fungus provides structure and moisture, while the alga produces food through photosynthesis.

Option C is an example of commensalism. The orchid benefits from the support and access to sunlight, while the tree is unaffected.

Option D is an example of parasitism. The cuckoo benefits by having its offspring raised without expending energy, while the host bird is harmed by wasting resources on raising another species’ young.

\(\Rightarrow D\)

BIOLOGY, M4 EQ-Bank 1 MC

Commensalism is a form of symbiotic relationship. Which of the following best describes a commensal relationship between two organisms?

  1. Both organisms benefit from the interaction.
  2. One organism benefits while the other is unaffected.
  3. One organism benefits at the expense of the other.
  4. Neither organism is affected by the interaction.
Show Answers Only

\(B\)

Show Worked Solution

→ In a commensal relationship, one organism benefits from the interaction while the other is neither helped nor harmed.

\(\Rightarrow B\)

BIOLOGY, M4 EQ-Bank 4

Describe the differences between mutualistic and parasitic symbiotic relationships in ecosystems. In your answer, provide one specific example of each type of relationship from nature.   (3 marks)

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→ Mutualistic and parasitic relationships are both types of symbiosis involving a relationship between two different species.

→ In a mutualistic relationship, both organisms benefit from the interaction.

→ Example: the relationship between clownfish and sea anemones, where the clownfish receive protection from predators among the anemone’s tentacles, while the anemone benefits from the fish’s waste products.

→ In contrast, in a parasitic relationship, one organism (the parasite) benefits at the expense of the other (the host). 

→ Example: tapeworms living in a dog’s intestine, where the tapeworm gains nutrients from the dog’s digested food, causing potential health issues for the dog without providing any benefits. 

Show Worked Solution

→ Mutualistic and parasitic relationships are both types of symbiosis involving a relationship between two different species.

→ In a mutualistic relationship, both organisms benefit from the interaction.

→ Example: the relationship between clownfish and sea anemones, where the clownfish receive protection from predators among the anemone’s tentacles, while the anemone benefits from the fish’s waste products.

→ In contrast, in a parasitic relationship, one organism (the parasite) benefits at the expense of the other (the host). 

→ Example: tapeworms living in a dog’s intestine, where the tapeworm gains nutrients from the dog’s digested food, causing potential health issues for the dog without providing any benefits. 

BIOLOGY, M4 EQ-Bank 2

  1. Is soil pH a biotic or abiotic factor?   (1 mark)
  2. Describe how soil pH can affect plant growth.   (1 mark)
  3. Explain one way in which plants might alter soil pH.   (1 mark)
Show Answers Only

a.   Abiotic factor
 

b.   Soil pH:

→ Affects plant growth by influencing nutrient availability and solubility.

→ Most plants thrive in slightly acidic to neutral soils (pH 6.0-7.0) where essential nutrients are most accessible.
 

c.   Plants alter soil pH (choose 1):

→ through root exudates, which release organic acids into the soil.

→ through the decomposition of their leaf litter, which can increase soil acidity over time.

Show Worked Solution

a.   Abiotic factor
 

b.   Soil pH:

→ Affects plant growth by influencing nutrient availability and solubility.

→ Most plants thrive in slightly acidic to neutral soils (pH 6.0-7.0) where essential nutrients are most accessible.
 

c.   Plants alter soil pH (choose 1):

→ through root exudates, which release organic acids into the soil.

→ through the decomposition of their leaf litter, which can increase soil acidity over time.

BIOLOGY, M4 EQ-Bank 3 MC

A scientist is using a population growth model to predict the future of a species in a changing environment. Which of the following factors would be LEAST likely to be included in this model?

  1. Birth rates and death rates of the species.
  2. Carrying capacity of the habitat.
  3. Genetic diversity within the population.
  4. Average daily temperature fluctuations.
Show Answers Only

\(D\)

Show Worked Solution

→ Population growth models typically focus on factors directly related to population dynamics such as birth rates, death rates, and carrying capacity.

→ While genetic diversity might be included in more complex models, average daily temperature fluctuations are too fine-grained for most population models and would be more relevant in climate models.

\(\Rightarrow D\)

BIOLOGY, M4 EQ-Bank 8

Indigenous land management practices are increasingly recognised for their effectiveness in ecosystem restoration.

Describe one specific case study where traditional knowledge has been applied to heal a damaged ecosystem in Australia. In your answer, explain the concept of 'Country' or 'Place' in this context and outline two specific restoration strategies used, highlighting their cultural significance.   (5 marks)

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Case study 1: Pilliga forest in NSW (one example of many)

→ In this context, ‘Country’ encompasses not just the physical landscape of the forest but the spiritual and cultural connections of the Aboriginal people.

→ Strategy 1: One key restoration strategy employed is the reintroduction of cultural burning practices. This traditional fire management technique helps reduce fuel loads, promote biodiversity, and encourages the growth of culturally significant plants.

→ Strategy 2: The restoration of natural water flows and wetlands, guided by traditional knowledge of the landscape was another restoration strategy used.

→ This approach not only improves water quality and habitat for native species but also revitalises culturally important water sites.

→ These strategies are culturally significant as they represent a continuation of ancestral practices and reinforce the Aboriginal people’s role as custodians of the land.
 

Case study 2: Restoration of the Gulgalda in Tasmania

→ Gulgalda is a critically endangered plant species sacred to the Tasmanian Aboriginal people.

→ In this context, ‘Country’ refers to not just the physical landscape but the interconnected relationships between land, plants and people, including spiritual and cultural elements.

→ Strategy 1: The use of cultural burning, a controlled fire management technique that stimulates Gulgalda germination and reduces competition from other plants.

→ Strategy 2: The project incorporated traditional harvesting practices, where plant material is collected sustainably to propagate new individuals while maintaining the spiritual connection to Country.

→ These strategies hold cultural significance as they preserve ancestral traditions and reaffirm the Aboriginal people’s stewardship over the land.

Show Worked Solution

Case study 1: Pilliga forest in NSW (one example of many)

→ In this context, ‘Country’ encompasses not just the physical landscape of the forest but the spiritual and cultural connections of the Aboriginal people.

→ Strategy 1: One key restoration strategy employed is the reintroduction of cultural burning practices. This traditional fire management technique helps reduce fuel loads, promote biodiversity, and encourages the growth of culturally significant plants.

→ Strategy 2: The restoration of natural water flows and wetlands, guided by traditional knowledge of the landscape was another restoration strategy used.

→ This approach not only improves water quality and habitat for native species but also revitalises culturally important water sites.

→ These strategies are culturally significant as they represent a continuation of ancestral practices and reinforce the Aboriginal people’s role as custodians of the land.
 

Case study 2: Restoration of the Gulgalda in Tasmania

→ Gulgalda is a critically endangered plant species sacred to the Tasmanian Aboriginal people.

→ In this context, ‘Country’ refers to not just the physical landscape but the interconnected relationships between land, plants and people, including spiritual and cultural elements.

→ Strategy 1: The use of cultural burning, a controlled fire management technique that stimulates Gulgalda germination and reduces competition from other plants.

→ Strategy 2: The project incorporated traditional harvesting practices, where plant material is collected sustainably to propagate new individuals while maintaining the spiritual connection to Country.

→ These strategies hold cultural significance as they preserve ancestral traditions and reaffirm the Aboriginal people’s stewardship over the land.

BIOLOGY, M4 EQ-Bank 7

Agricultural intensification has led to widespread land degradation in many parts of the world. 

Identify two major forms of land degradation resulting from agricultural practices. In your answer, describe a specific restoration technique used to address each form of degradation.   (4 marks)

Show Answers Only

Soil erosion:

→ Soil erosion is a major form of land degradation that is caused by intensive cropping and overgrazing.

→ It can be addressed through crop rotation and destocking. These strategies help to stabilise soil structure, increase organic matter, and reduce erosion.
 

Soil salinisation:

→ Soil salinisation is a form of land degradation whereby excessive salts accumulate in the soil, reducing its fertility and hindering plant growth.

→ It is often caused by poor irrigation practices and can be mitigated through the use of salt-tolerant crops and improved drainage systems.

Show Worked Solution

Soil erosion:

→ Soil erosion is a major form of land degradation that is caused by intensive cropping and overgrazing.

→ It can be addressed through crop rotation and destocking. These strategies help to stabilise soil structure, increase organic matter, and reduce erosion.
 

Soil salinisation:

→ Soil salinisation is a form of land degradation whereby excessive salts accumulate in the soil, reducing its fertility and hindering plant growth.

→ It is often caused by poor irrigation practices and can be mitigated through the use of salt-tolerant crops and improved drainage systems.

BIOLOGY, M4 EQ-Bank 6

The concept of 'Country' holds deep significance in Aboriginal culture.

Explain the meaning of 'Country' from an Aboriginal perspective and describe a restoration practice that aligns with Aboriginal understanding of Country and could be used in post-mining landscapes.   (3 marks)

Show Answers Only

→ In Aboriginal culture, ‘Country’ refers to a holistic concept that encompasses not just the physical landscape, but also spiritual and cultural connections.

→ It’s a living entity that Aboriginal people have a responsibility to care for and maintain.

Restoration process (could include one of the following):

→ A restoration practice that aligns with this understanding is the use of cultural burning, a traditional land management technique. This controlled, low-intensity burning, guided by Indigenous knowledge, can be applied in post-mining landscapes to promote traditional biodiversity and reduce wildfire risk. 

→ The promotion and funding of Aboriginal custodians to teach the skills of bush regeneration to younger generations.

Show Worked Solution

→ In Aboriginal culture, ‘Country’ refers to a holistic concept that encompasses not just the physical landscape, but also spiritual and cultural connections.

→ It’s a living entity that Aboriginal people have a responsibility to care for and maintain.

Restoration process (could include one of the following):

→ A restoration practice that aligns with this understanding is the use of cultural burning, a traditional land management technique. This controlled, low-intensity burning, guided by Indigenous knowledge, can be applied in post-mining landscapes to promote traditional biodiversity and reduce wildfire risk. 

→ The promotion and funding of Aboriginal custodians to teach the skills of bush regeneration to younger generations.

BIOLOGY, M4 EQ-Bank 5

Mining activities often leave significant impacts on ecosystems. Environmental scientists and ecologists work to develop and implement restoration practices to heal these damaged landscapes.

Describe two specific restoration practices commonly used in post-mining landscapes. In your answer, identify one challenge faced in the restoration process and how it might be overcome.   (4 marks)

Show Answers Only

Restoration practices (choose 2)

→ Practice 1: Topsoil replacement involves carefully storing the original topsoil during mining operations and then reapplying it during restoration, which helps to preserve the soil’s seed bank and beneficial microorganisms.

→ Practice 2: Native species revegetation focuses on planting local plant species to re-establish the area’s natural ecosystem.

→ Practice 2: Hydrological restoration aims to re-establish natural water flows and drainage patterns disrupted by mining activities. This can involve reshaping the landscape to mimic natural contours and/or creating wetlands.
 

Restoration challenge/response:

→ A significant challenge in the restoration process is soil compaction, which can occur due to heavy machinery used during mining and restoration activities.

→ This challenge can be addressed through techniques such as deep ripping, where the soil is mechanically loosened to improve its structure, or by using native plant species with deep root systems that can penetrate and gradually improve compacted soils over time.

Show Worked Solution

Restoration practices (choose 2)

→ Practice 1: Topsoil replacement involves carefully storing the original topsoil during mining operations and then reapplying it during restoration, which helps to preserve the soil’s seed bank and beneficial microorganisms.

→ Practice 2: Native species revegetation focuses on planting local plant species to re-establish the area’s natural ecosystem.

→ Practice 2: Hydrological restoration aims to re-establish natural water flows and drainage patterns disrupted by mining activities. This can involve reshaping the landscape to mimic natural contours and/or creating wetlands.
 

Restoration challenge/response:

→ A significant challenge in the restoration process is soil compaction, which can occur due to heavy machinery used during mining and restoration activities.

→ This challenge can be addressed through techniques such as deep ripping, where the soil is mechanically loosened to improve its structure, or by using native plant species with deep root systems that can penetrate and gradually improve compacted soils over time.

BIOLOGY, M4 EQ-Bank 4

While models provide valuable insights into potential biodiversity changes, they are not without their shortcomings.

Identify and explain two limitations of models used to predict future impacts on biodiversity. In your answer suggest a way scientists might address or mitigate these limitations.   (4 marks)

Show Answers Only

Limitation: inadequate data

→ Model accuracy requires adequate data which can be expensive and difficult to obtain.

→ To address this, scientists can use developing technology to capture more data and use machine learning techniques to better interpret that data.
 

Limitation: inaccurate model inputs (projections)

→ Models often require projections of human behaviour, such as greenhouse gas emissions, which can be highly unpredictable.

→ This uncertainty can significantly affect the accuracy of long-term biodiversity predictions.

→ One way to mitigate this limitation is to use scenario-based modelling, where multiple possible futures are simulated based on different human activity projections.
 

Limitation: complexity of the system being modelled

→ Ecological interactions are complex systems with unpredictable feedback loops. These systems are extremely difficulty to model.

→ Scientists need to be aware of and incorporate other research into their model. For example, (unexpected) massive methane releases as permafrost melts in the Arctic should be included in any climate model as the science becomes known.

Show Worked Solution

Limitation: inadequate data

→ Model accuracy requires adequate data which can be expensive and difficult to obtain.

→ To address this, scientists can use developing technology to capture more data and use machine learning techniques to better interpret that data.
 

Limitation: inaccurate model inputs (projections)

→ Models often require projections of human behaviour, such as greenhouse gas emissions, which can be highly unpredictable.

→ This uncertainty can significantly affect the accuracy of long-term biodiversity predictions.

→ One way to mitigate this limitation is to use scenario-based modelling, where multiple possible futures are simulated based on different human activity projections.
 

Limitation: complexity of the system being modelled

→ Ecological interactions are complex systems with unpredictable feedback loops. These systems are extremely difficulty to model.

→ Scientists need to be aware of and incorporate other research into their model. For example, (unexpected) massive methane releases as permafrost melts in the Arctic should be included in any climate model as the science becomes known.

CHEMISTRY, M3 EQ-Bank 20

During a laboratory investigation, a student mixed two solutions and observed a sudden colour change, an increase in temperature, and the formation of bubbles.

  1. Explain why these observations indicate a chemical change.   (3 marks)
  1. Discuss two types of chemical reactions that could cause at least two of these observations each.   (2 marks)
Show Answers Only

a.   Colour Change:

→ This suggests that new chemical compounds are forming that have different properties from the original reactants.

Temperature Increase (Exothermic Reaction):

→ The release of heat indicates that the reaction is exothermic, where energy is released as bonds are formed in the products.

Gas Production (Bubbles):

→ The formation of bubbles without boiling is a sign that a gas is being produced as a result of the reaction.
 

b.   Acid-Base Reaction:

→ When an acid reacts with a base, it can lead to a colour change if an indicator is present (e.g., phenolphthalein changes from colourless to pink). An exothermic reaction may also occur, causing a temperature increase.

Decomposition Reaction:

→ Certain decomposition reactions, such as the breakdown of hydrogen peroxide, produce gas (oxygen) and heat. The bubbling and increase in temperature can be observed in this type of reaction.

Show Worked Solution

a.   Colour Change:

→ This suggests that new chemical compounds are forming that have different properties from the original reactants.

Temperature Increase (Exothermic Reaction):

→ The release of heat indicates that the reaction is exothermic, where energy is released as bonds are formed in the products.

Gas Production (Bubbles):

→ The formation of bubbles without boiling is a sign that a gas is being produced as a result of the reaction.
 

b.   Acid-Base Reaction:

→ When an acid reacts with a base, it can lead to a colour change if an indicator is present (e.g., phenolphthalein changes from colourless to pink). An exothermic reaction may also occur, causing a temperature increase.

Decomposition Reaction:

→ Certain decomposition reactions, such as the breakdown of hydrogen peroxide, produce gas (oxygen) and heat. The bubbling and increase in temperature can be observed in this type of reaction.

CHEMISTRY, M3 EQ-Bank 8 MC

A student conducts an experiment by mixing an unknown metal powder with a solution of hydrochloric acid. The following observations are made: rapid bubbling, a slight rise in temperature, and a distinctive metallic odour.

Based on these observations, which of the following best identifies the indicators of a chemical change and explains what might have occurred?

  1. Formation of a precipitate, indicating the metal is insoluble in acid.
  2. Production of a gas and increase in temperature, suggesting the metal reacts to release hydrogen gas.
  3. Emission of light and production of an odor, implying the metal is highly reactive.
  4. Absorption of heat and production of a gas, indicating an endothermic reaction producing carbon dioxide.
Show Answers Only

\(B\)

Show Worked Solution

→ The rapid bubbling indicates the release of a gas, likely hydrogen, which is common when active metals react with acids. The slight rise in temperature suggests an exothermic reaction.

→ The presence of a metallic odour might be due to vaporization of trace compounds.

→ Therefore, the correct indicators are gas production and temperature change, which signify a chemical reaction.

\(\Rightarrow B\)

CHEMISTRY, M3 EQ-Bank 6 MC

Which of the following correctly identifies the gas or gases released when hydrochloric acid reacts with magnesium, potassium hydroxide, calcium carbonate, and ammonium carbonate, respectively?

\begin{align*}
\begin{array}{l}
\ & \\
\textbf{A.}\\
\textbf{B.}\\
\textbf{C.}\\
\textbf{D.}\\
\end{array}
\begin{array}{|l|l|l|l|}
\hline
\textit{Magnesium} & \textit{Potassium hydroxide} & \textit{Calcium carbonate} & \textit{Ammonium carbonate} \\
\hline
\text{No gas} & \text{Hydrogen} & \text{Carbon dioxide} & \text{Carbon dioxide and ammonia} \\
\hline
\text{Hydrogen} & \text{No gas} & \text{Carbon dioxide} & \text{Ammonia} \\
\hline
\text{Carbon dioxide} & \text{Hydrogen} & \text{No Gas} & \text{Carbon dioxide} \\
\hline
\text{Hydrogen} & \text{No gas} & \text{Carbon Dioxide} & \text{Carbon dioxide} \\
\hline
\end{array}
\end{align*}

Show Answers Only

\(D\)

Show Worked Solution

→ \(\ce{Mg(s) + 2HCl(aq) -> MgCl2(aq) + H2(g)}\)  (Hydrogen gas produced)

→ \(\ce{KOH(aq) + HCl(aq) -> KCl(aq) + H2O(l)}\)  (No gas produced)

→ \(\ce{CaCO3(s) + 2HCl(aq) -> CaCl2(aq) + CO2(g) + H2O(l)}\)  (Carbon dioxide produced)

→ \(\ce{(NH4)2CO3(s) + 2HCl(aq) -> 2NH4Cl(aq) + CO2(g) + H2O(l)}\)  (Carbon dioxide produced)

\(\Rightarrow D\)

CHEMISTRY, M3 EQ-Bank 18

A student heats sodium metal, copper carbonate and propane gas \(\ce{(C3H8)}\) individually with a Bunsen burner. All of the substances react but only two of the substances react with the oxygen in the air.

Write a balanced chemical equation for each of the reactions that occurred.   (3 marks)

Show Answers Only

Combustion of sodium metal:  \(\ce{2Na(s) + O2(g) -> 2NaO(s)}\)

Combustion of propane gas:  \(\ce{C3H8(g) + 5O2(g) -> 3CO2(g) + 4H2O(l)}\)

Decomposition of copper carbonate:  \(\ce{CuCO3(s) -> CuO(s) + CO2(g)}\)

Show Worked Solution

Combustion of sodium metal:  \(\ce{2Na(s) + O2(g) -> 2NaO(s)}\)

Combustion of propane gas:  \(\ce{C3H8(g) + 5O2(g) -> 3CO2(g) + 4H2O(l)}\)

Decomposition of copper carbonate:  \(\ce{CuCO3(s) -> CuO(s) + CO2(g)}\)

→ The last reaction is endothermic and so requires the heat of the Bunsen burner to proceed where as the first two require the heat of the Bunsen burner to overcome their activation energies.

BIOLOGY, M4 EQ-Bank 8

Explain how the unique abiotic factors of the Australian continent have influenced the evolution of sclerophyll plants. In your answer, provide two specific adaptations.   (4 marks)

Show Answers Only

→ The evolution of sclerophyll plants in Australia is closely tied to the continent’s abiotic factors, particularly its nutrient-poor soils, arid climate, and frequent bushfires.

→ These plants have developed tough, leathery leaves with a thick cuticle to reduce water loss in the dry Australian environment, a key adaptation to water scarcity.

→ Sclerophyll species like eucalypts and banksias have also evolved strategies to cope with nutrient-poor soils, such as cluster roots that efficiently extract phosphorus.

→ Many sclerophyll plants have developed fire-resistant adaptations, including lignotubers for post-fire regeneration and fruits that release seeds after fire.

→ These adaptations demonstrate how the challenging abiotic conditions in Australia have acted as strong selective pressures, shaping the evolution of a unique flora highly specialised for survival in this harsh environment.

Show Worked Solution

→ The evolution of sclerophyll plants in Australia is closely tied to the continent’s abiotic factors, particularly its nutrient-poor soils, arid climate, and frequent bushfires.

→ These plants have developed tough, leathery leaves with a thick cuticle to reduce water loss in the dry Australian environment, a key adaptation to water scarcity.

→ Sclerophyll species like eucalypts and banksias have also evolved strategies to cope with nutrient-poor soils, such as cluster roots that efficiently extract phosphorus.

→ Many sclerophyll plants have developed fire-resistant adaptations, including lignotubers for post-fire regeneration and fruits that release seeds after fire.

→ These adaptations demonstrate how the challenging abiotic conditions in Australia have acted as strong selective pressures, shaping the evolution of a unique flora highly specialised for survival in this harsh environment.

BIOLOGY, M4 EQ-Bank 7

Analyse the evidence for the evolution of marsupials in Australia. In your answer, describe one piece of fossil evidence that supports the evolution of marsupials in Australia and provide one limitation of using fossil evidence to reconstruct evolutionary histories.   (4 marks)

Show Answers Only

→ Fossil evidence strongly supports the evolution of marsupials in Australia.

→ Riversleigh fossil deposits in Queensland provide important fossil evidence from 33 Mya. These deposits contain marsupial fossils of the ancestors of modern kangaroos, koalas, and wombats.

→ The diversity and age of these fossils demonstrate the long evolutionary history of marsupials on the Australian continent and provide insights into their adaptive radiation into various ecological niches. 

→ A limitation of using fossil evidence to reconstruct evolutionary histories is the incompleteness of the fossil record.

→ Many species may not fossilise due to their soft bodies or the absence of suitable preservation conditions, leading to gaps in our understanding of evolutionary transitions.

Show Worked Solution

→ Fossil evidence strongly supports the evolution of marsupials in Australia.

→ Riversleigh fossil deposits in Queensland provide important fossil evidence from 33 Mya. These deposits contain marsupial fossils of the ancestors of modern kangaroos, koalas, and wombats.

→ The diversity and age of these fossils demonstrate the long evolutionary history of marsupials on the Australian continent and provide insights into their adaptive radiation into various ecological niches. 

→ A limitation of using fossil evidence to reconstruct evolutionary histories is the incompleteness of the fossil record.

→ Many species may not fossilise due to their soft bodies or the absence of suitable preservation conditions, leading to gaps in our understanding of evolutionary transitions.

BIOLOGY, M4 EQ-Bank 5

Scientists analyse the ratio of \(\ce{^{16}O}\) to \(\ce{^{18}O}\) isotopes in various geological samples to reconstruct past climatic conditions.

  1. Describe one method used to obtain oxygen isotope data from ancient samples.   (1 mark)

  2. Explain how the relationship between \(\ce{^{16}O}\) and \(\ce{^{18}O}\) ratios provides evidence of past changes in ecosystems.   (3 marks)

Show Answers Only

a.   Scientists analyse gas trapped within ice cores.

b.   \(\ce{^{16}O : ^{18}O}\) ratios

→ The ratio of \(\ce{^{16}O : ^{18}O}\) in geological samples reflects past temperature and precipitation patterns, which are crucial factors in shaping ecosystems.

→ During warmer periods, there is a higher proportion of the heavier \(\ce{^{18}O}\) isotope in precipitation.

→ During cooler periods, there is a relative increase in lighter \(\ce{^{16}O}\).

→ These isotopic signatures allow scientists to reconstruct past climate conditions and infer associated ecosystem changes.

Show Worked Solution

a.   Scientists analyse gas trapped within ice cores.

b.   \(\ce{^{16}O : ^{18}O}\) ratios

→ The ratio of \(\ce{^{16}O : ^{18}O}\) in geological samples reflects past temperature and precipitation patterns, which are crucial factors in shaping ecosystems.

→ During warmer periods, there is a higher proportion of the heavier \(\ce{^{18}O}\) isotope in precipitation.

→ During cooler periods, there is a relative increase in lighter \(\ce{^{16}O}\).

→ These isotopic signatures allow scientists to reconstruct past climate conditions and infer associated ecosystem changes.

BIOLOGY, M4 EQ-Bank 2

Aboriginal rock paintings provide valuable insights into Australia's past ecosystems and the changes they've undergone over time.

Explain why Aboriginal rock paintings are considered a valid source of ecological information and how it complements other forms of paleontological data in understanding ecosystem changes.   (4 marks)

Show Answers Only

→ Aboriginal rock paintings provide direct visual records of flora and fauna from thousands of years ago.

→ These paintings were created by people who closely observed their environment.

→ A notable example is the Nawarla Gabarnmang rock art site in Arnhem Land, which features a painting of a thylacine (Tasmanian tiger) dated to be at least 17,000 years old.

→ This painting provides evidence that thylacines once inhabited mainland Australia, long after they had disappeared from the fossil record in this region.

→ In this way, Aboriginal rock art sites help to fill gaps in the paleontological record and provides insights into the distribution of this species before its mainland extinction.

→ By comparing such rock art with current ecosystems, scientists can infer changes in biodiversity, contributing to our understanding of long-term ecological changes in Australia.

Show Worked Solution

→ Aboriginal rock paintings provide direct visual records of flora and fauna from thousands of years ago.

→ These paintings were created by people who closely observed their environment.

→ A notable example is the Nawarla Gabarnmang rock art site in Arnhem Land, which features a painting of a thylacine (Tasmanian tiger) dated to be at least 17,000 years old.

→ This painting provides evidence that thylacines once inhabited mainland Australia, long after they had disappeared from the fossil record in this region.

→ In this way, Aboriginal rock art sites help to fill gaps in the paleontological record and provides insights into the distribution of this species before its mainland extinction.

→ By comparing such rock art with current ecosystems, scientists can infer changes in biodiversity, contributing to our understanding of long-term ecological changes in Australia.

BIOLOGY, M4 EQ-Bank 1

Describe two examples of paleontological evidence from Australia that provide insights into past changes in ecosystems.   (4 marks)

Show Answers Only

Example 1: Megafauna fossils in the Naracoorte Caves, South Australia

→ The Naracoorte Caves contain fossil record of Australian megafauna, including giant kangaroos and marsupial lions, dating back to the Pleistocene epoch.

→ These fossils provide evidence of a dramatic shift in Australia’s ecosystem, from one that supported large herbivores and their predators to the current environment dominated by smaller species.

→ The disappearance of these megafauna species from the fossil record around 46,000 years ago coincides with human arrival in Australia, suggesting a potential link between human activity and ecosystem change. 
 

Example 2: Plant microfossils from the Atherton Tablelands, Qld

→ Sediment cores from crater lakes in the Atherton Tablelands contain plant microfossils such as pollen grains that date back over 200,000 years.

→ Analysis of these microfossils reveals changes in vegetation types over time, indicating shifts between rainforest and dry forest dominance in response to climate fluctuations.

→ This evidence provides a detailed record of how Australian plant communities have responded to past climate changes, including glacial and interglacial periods. 

Show Worked Solution

Example 1: Megafauna fossils in the Naracoorte Caves, South Australia

→ The Naracoorte Caves contain fossil record of Australian megafauna, including giant kangaroos and marsupial lions, dating back to the Pleistocene epoch.

→ These fossils provide evidence of a dramatic shift in Australia’s ecosystem, from one that supported large herbivores and their predators to the current environment dominated by smaller species.

→ The disappearance of these megafauna species from the fossil record around 46,000 years ago coincides with human arrival in Australia, suggesting a potential link between human activity and ecosystem change. 
 

Example 2: Plant microfossils from the Atherton Tablelands, Qld

→ Sediment cores from crater lakes in the Atherton Tablelands contain plant microfossils such as pollen grains that date back over 200,000 years.

→ Analysis of these microfossils reveals changes in vegetation types over time, indicating shifts between rainforest and dry forest dominance in response to climate fluctuations.

→ This evidence provides a detailed record of how Australian plant communities have responded to past climate changes, including glacial and interglacial periods. 

BIOLOGY, M3 EQ-Bank 9

Researchers have observed significant changes in cane toad populations since their introduction to Australia.

Describe one modern-day adaptation discovered in cane toads how it relates to the process of natural selection.   (3 marks)

Show Answers Only

→ Recent studies have revealed that cane toads at the invasion front in Australia have evolved to disperse more rapidly than their ancestors.

→ These modern toads have developed longer legs, allowing them to hop faster,  cover greater distances and colonise new areas more quickly than initially predicted.

→ These changes support natural selection by demonstrating an inherited trait that is passed to offspring and becomes more common in the population.

→ However, researchers have also found that faster “front line” cane toads are more likely to be eaten, breed less and have more spine arthritis than their ancestors.

→ The natural selection principle of traits that enhance survival and reproductive success being passed on is seemingly contradicted by these findings.

Show Worked Solution

→ Recent studies have revealed that cane toads at the invasion front in Australia have evolved to disperse more rapidly than their ancestors.

→ These modern toads have developed longer legs, allowing them to hop faster,  cover greater distances and colonise new areas more quickly than initially predicted.

→ These changes support natural selection by demonstrating an inherited trait that is passed to offspring and becomes more common in the population.

→ However, researchers have also found that faster “front line” cane toads are more likely to be eaten, breed less and have more spine arthritis than their ancestors.

→ The natural selection principle of traits that enhance survival and reproductive success being passed on is seemingly contradicted by these findings.

BIOLOGY, M3 EQ-Bank 8

Absolute dating techniques provide crucial information about the age of fossils and rocks, but different methods are suitable for different time periods.

Describe two absolute dating methods used by scientists, each appropriate for a different time scale.   (4 marks)

Show Answers Only

Carbon-14 dating:

→ Carbon-14 dating is an absolute dating method used for relatively recent organic materials. It’s based on the decay of radioactive carbon-14 to nitrogen-14.

→ Carbon-14 has a half-life of 5730 years and measuring the ratio of carbon-14 to stable carbon-12, scientists can determine when the organism died.

→ Carbon-14 dating is most effective for materials up to about 50,000 years old, making it useful for dating recent fossils.
 

Potassium-40 dating:

→ Potassium-40 dating is an absolute dating technique that can be used for much older materials.

→ It’s based on the decay of radioactive potassium-40 to argon-40. This method is effective for dating rocks and minerals containing potassium, typically those of igneous or metamorphic origin.

→ Potassium-40 has a half-life of about 1.3 billion years, making this method suitable for dating ancient fossils and rock layers from 50,000 to billions of years old.

Show Worked Solution

Carbon-14 dating:

→ Carbon-14 dating is an absolute dating method used for relatively recent organic materials. It’s based on the decay of radioactive carbon-14 to nitrogen-14.

→ Carbon-14 has a half-life of 5730 years and measuring the ratio of carbon-14 to stable carbon-12, scientists can determine when the organism died.

→ Carbon-14 dating is most effective for materials up to about 50,000 years old, making it useful for dating recent fossils.
 

Potassium-40 dating:

→ Potassium-40 dating is an absolute dating technique that can be used for much older materials.

→ It’s based on the decay of radioactive potassium-40 to argon-40. This method is effective for dating rocks and minerals containing potassium, typically those of igneous or metamorphic origin.

→ Potassium-40 has a half-life of about 1.3 billion years, making this method suitable for dating ancient fossils and rock layers from 50,000 to billions of years old.

BIOLOGY, M3 EQ-Bank 6

Paleontologists use various methods to determine the age of fossils, providing crucial information about Earth's history and the evolution of life.

Describe two techniques that can be used to date fossils. In your answer, discuss one advantage and one limitation of each method.   (4 marks)

Show Answers Only

Stratigraphy:

→ Stratigraphy is a relative dating technique based on the principle that sedimentary rocks are deposited in layers, with older layers at the bottom and younger layers on top.

→ An advantage of stratigraphy is that it can provide relative ages for fossils without requiring specialised equipment.

→ However, a limitation is that it only provides relative dates, not absolute ages, and can be disrupted by geological processes like folding or faulting.
 

Radiocarbon dating:

→ Radiocarbon dating is an absolute dating technique used to determine the age of organic materials up to about 50,000 years old by measuring the decay of radioactive carbon-14 in fossils.

→ An advantage of this method is that it can provide precise absolute dates for relatively recent fossils.

→ However, a limitation is its restricted time range; it cannot be used for fossils older than about 50,000 years because most of the carbon-14 will have decayed.

Show Worked Solution

Stratigraphy:

→ Stratigraphy is a relative dating technique based on the principle that sedimentary rocks are deposited in layers, with older layers at the bottom and younger layers on top.

→ An advantage of stratigraphy is that it can provide relative ages for fossils without requiring specialised equipment.

→ However, a limitation is that it only provides relative dates, not absolute ages, and can be disrupted by geological processes like folding or faulting.
 

Radiocarbon dating:

→ Radiocarbon dating is an absolute dating technique used to determine the age of organic materials up to about 50,000 years old by measuring the decay of radioactive carbon-14 in fossils.

→ An advantage of this method is that it can provide precise absolute dates for relatively recent fossils.

→ However, a limitation is its restricted time range; it cannot be used for fossils older than about 50,000 years because most of the carbon-14 will have decayed.

BIOLOGY, M3 EQ-Bank 3

Ginkgo biloba, often called a 'living fossil', is the only surviving species of the division Ginkgophyta. While native to China today, fossils of ginkgo-like plants have been found on every continent except Antarctica.

These fossils date back to the Permian period, over 270 million years ago. Ginkgo fossils have been discovered in locations as diverse as North America, Europe, and Australia.

Explain how this widespread fossil distribution of Ginkgo, compared to its limited native range today, supports the theory of evolution by natural selection.   (4 marks)

Show Answers Only

→ The presence of Ginkgo fossils on multiple continents can be explained by the existence of the supercontinent Pangaea, which began breaking up about 200 million years ago.

→ Ginkgo-like plants were already present before this breakup, allowing their fossils to be distributed across what would become separate continents.

→ As continents drifted apart and climates changed over millions of years, Ginkgo species faced varying selection pressures in different regions.

→ In many areas, these pressures led to the extinction of local Ginkgo populations, demonstrating natural selection in action.

→ The survival of Ginkgo biloba shows the process of evolutionary adaptation. Its survival is likely due to traits that were advantageous within its specific environment, illustrating how environmental changes can drive both extinction and adaptation, key concepts in Darwin and Wallace’s theory.

Show Worked Solution

→ The presence of Ginkgo fossils on multiple continents can be explained by the existence of the supercontinent Pangaea, which began breaking up about 200 million years ago.

→ Ginkgo-like plants were already present before this breakup, allowing their fossils to be distributed across what would become separate continents.

→ As continents drifted apart and climates changed over millions of years, Ginkgo species faced varying selection pressures in different regions.

→ In many areas, these pressures led to the extinction of local Ginkgo populations, demonstrating natural selection in action.

→ The survival of Ginkgo biloba shows the process of evolutionary adaptation. Its survival is likely due to traits that were advantageous within its specific environment, illustrating how environmental changes can drive both extinction and adaptation, key concepts in Darwin and Wallace’s theory.

BIOLOGY, M3 EQ-Bank 4

Comparative embryology provides compelling evidence for Darwin and Wallace's Theory of Evolution by Natural Selection.

Describe two examples of embryological similarities across different species and explain how these examples support the theory of evolution.   (4 marks)

Show Answers Only

Answers could include two of the following:

Gill slits

→ Gill-like structures appear in both fish and human embryos during early development.

→ In humans, these structures eventually develop into various head and neck tissues, while in fish they form gills.

→ This shared developmental pattern supports the Darwin/Wallace theory by indicating a common ancestral origin between humans and fish, despite their vastly different adult forms and habitats.
 

Tail bones

→ A tail appears in human embryos, complete with several vertebrae. This resembles the tails of other mammals and is typically reabsorbed before birth.

→ Its presence in human embryos, despite humans being tailless as adults, indicates our evolutionary relationship with other mammals and supports the Darwin/Wallace theory.
 

Pharyngeal arches

→ Pharyngeal arch structures appear in fish, amphibians, reptiles, birds, and mammals during early development, despite their diverse adult forms.

→ In fish, they develop into gill arches, while in mammals they contribute to structures like the jaw and inner ear bones.

→ This similarity suggests a common evolutionary origin for all vertebrates, supporting Darwin and Wallace’s concept of descent with modification.

Show Worked Solution

Answers could include two of the following:

Gill slits

→ Gill-like structures appear in both fish and human embryos during early development.

→ In humans, these structures eventually develop into various head and neck tissues, while in fish they form gills.

→ This shared developmental pattern supports the Darwin/Wallace theory by indicating a common ancestral origin between humans and fish, despite their vastly different adult forms and habitats.
 

Tail bones

→ A tail appears in human embryos, complete with several vertebrae. This resembles the tails of other mammals and is typically reabsorbed before birth.

→ Its presence in human embryos, despite humans being tailless as adults, indicates our evolutionary relationship with other mammals and supports the Darwin/Wallace theory.
 

Pharyngeal arches

→ Pharyngeal arch structures appear in fish, amphibians, reptiles, birds, and mammals during early development, despite their diverse adult forms.

→ In fish, they develop into gill arches, while in mammals they contribute to structures like the jaw and inner ear bones.

→ This similarity suggests a common evolutionary origin for all vertebrates, supporting Darwin and Wallace’s concept of descent with modification.

BIOLOGY, M3 EQ-Bank 5

On a remote island, a group of flightless birds called the Insulavis live peacefully.

These birds have small, stubby appendages where their wings should be. Despite never using these appendages for flight, every Insulavis is born with them.

Using your understanding of Darwin and Wallace's Theory of Evolution by Natural Selection, explain how the presence of these structures in Insulavis supports the theory of evolution. In your answer, provide a possible evolutionary scenario that could have led to the current state of Insulavis wings.   (4 marks)

Show Answers Only

→ The small wing appendages of the Insulavis are vestigial structures, which provide strong support for the theory.

→ These structures indicate that Insulavis likely descended from flying ancestors, but over time, as the birds adapted to their island environment where flight was unnecessary or disadvantageous, their wings gradually reduced in size and functionality.

→ Natural selection would have favoured individuals with smaller wings, as they might have required less energy to maintain or provided other benefits in their flightless lifestyle.

→ This gradual reduction in wing size over many generations demonstrates the principle of descent with modification, a key component of evolutionary theory.

→ The presence of these vestigial wings in all Insulavis individuals shows how evolutionary history is preserved in an organism’s anatomy, even as it adapts to new environmental pressures.

Show Worked Solution

→ The small wing appendages of the Insulavis are vestigial structures, which provide strong support for the theory.

→ These structures indicate that Insulavis likely descended from flying ancestors, but over time, as the birds adapted to their island environment where flight was unnecessary or disadvantageous, their wings gradually reduced in size and functionality.

→ Natural selection would have favoured individuals with smaller wings, as they might have required less energy to maintain or provided other benefits in their flightless lifestyle.

→ This gradual reduction in wing size over many generations demonstrates the principle of descent with modification, a key component of evolutionary theory.

→ The presence of these vestigial wings in all Insulavis individuals shows how evolutionary history is preserved in an organism’s anatomy, even as it adapts to new environmental pressures.

CHEMISTRY, M3 EQ-Bank 5 MC

Which fuel produces the highest number of moles of carbon dioxide for every mole of oxygen consumed during complete combustion?

  1. Ethane, \(\ce{C2H6}\)
  2. Ethene, \(\ce{C2H4}\)
  3. Methane, \(\ce{CH4}\)
  4. Butane, \(\ce{C4H10}\)
Show Answers Only

\(B\)

Show Worked Solution

Ethane: \(\ce{2C2H6 + 7O2 -> 4CO2 + 6H2O}\),   \(\ce{\frac{4}{7}CO2}\) per mole of \(\ce{O2}\)

Ethene: \(\ce{C2H4 + 3O2 -> 2CO2 + 2H2O}\),   \(\ce{\frac{2}{3}CO2}\) per mole of \(\ce{O2}\)

Methane: \(\ce{CH4 + 2O2 -> CO2 + 2H2O}\),   \(\ce{\frac{1}{2}CO2}\) per mole of \(\ce{O2}\)

Butane: \(\ce{2C4H10 + 13O2 -> 8CO2 + 10H2O}\),   \(\ce{\frac{8}{13}CO2}\) per mole of \(\ce{O2}\)

→ Ethene has the highest amount of \(\ce{CO2}\) per mole of \(\ce{O2}\) used up in the reaction.

\(\Rightarrow B\)

 

CHEMISTRY, M3 EQ-Bank 16

Describe how activation energy, collision frequency, and molecular orientation work together to determine the rate of a chemical reaction. In your answer, define what each term refers to and relate these factors to collision theory.   (5 marks)

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→ Activation Energy: For a reaction to occur, the colliding molecules must have enough energy to overcome the activation energy barrier, which is the minimum energy required to break the bonds in the reactants and initiate the reaction. 

→ Collision Frequency: The rate of a reaction is also influenced by how frequently reactant molecules collide.

→ Molecular Orientation: In addition to having enough energy, molecules must collide with the correct orientation for a reaction to take place. Reactant molecules need to align in a way that allows bonds to break and new bonds to form. 

→ Increasing collision frequency increases the number of opportunities for molecules to collide, but only those collisions with enough energy and the correct orientation will lead to successful bond rearrangements.

→ For the maximum rate of reaction there needs to be a lower activation energy which makes it easier for collisions to result in a reaction, the proper orientation that ensures when collisions occur, they lead to the formation of products and a high collision frequency.

Show Worked Solution

→ Activation Energy: For a reaction to occur, the colliding molecules must have enough energy to overcome the activation energy barrier, which is the minimum energy required to break the bonds in the reactants and initiate the reaction. 

→ Collision Frequency: The rate of a reaction is also influenced by how frequently reactant molecules collide.

→ Molecular Orientation: In addition to having enough energy, molecules must collide with the correct orientation for a reaction to take place. Reactant molecules need to align in a way that allows bonds to break and new bonds to form. 

→ Increasing collision frequency increases the number of opportunities for molecules to collide, but only those collisions with enough energy and the correct orientation will lead to successful bond rearrangements.

→ For the maximum rate of reaction there needs to be a lower activation energy which makes it easier for collisions to result in a reaction, the proper orientation that ensures when collisions occur, they lead to the formation of products and a high collision frequency.

BIOLOGY, M3 EQ-Bank 3

"Natural selection is the architect of biodiversity."

Justify this statement. In your answer, describe how natural selection can lead to changes in a population and over time, increased biodiversity. Provide an example from the Australian ecosystems that demonstrates this relationship.   (5 marks)

Show Answers Only

→ Natural selection is the architect of biodiversity as it drives the adaptation of populations to their environments, leading to the evolution of new species over time.

→ This process begins with genetic variations within a population, where individuals with traits better suited to their environment are more likely to survive and reproduce, passing these beneficial traits to their offspring.

→ Over generations, this can lead to significant changes in the population, potentially resulting in the emergence of new species adapted to specific environmental niches.

→ As populations adapt to different environments or ecological roles, the overall biodiversity increases.

→ Australian ecosystem example: the radiation of marsupials, such as the diverse kangaroo species.

→ From a common ancestor, natural selection has led to the evolution of various kangaroo species adapted to different habitats, from the large red kangaroos of the arid interior to the tree-dwelling tree-kangaroos of the rainforests.

→ Each fill a unique ecological niche and contribute to Australia’s biodiversity.

Show Worked Solution

→ Natural selection is the architect of biodiversity as it drives the adaptation of populations to their environments, leading to the evolution of new species over time.

→ This process begins with genetic variations within a population, where individuals with traits better suited to their environment are more likely to survive and reproduce, passing these beneficial traits to their offspring.

→ Over generations, this can lead to significant changes in the population, potentially resulting in the emergence of new species adapted to specific environmental niches.

→ As populations adapt to different environments or ecological roles, the overall biodiversity increases.

→ Australian ecosystem example: the radiation of marsupials, such as the diverse kangaroo species.

→ From a common ancestor, natural selection has led to the evolution of various kangaroo species adapted to different habitats, from the large red kangaroos of the arid interior to the tree-dwelling tree-kangaroos of the rainforests.

→ Each fill a unique ecological niche and contribute to Australia’s biodiversity.

BIOLOGY, M3 EQ-Bank 2

  1. Define convergent evolution within the context of Darwin and Wallace's Theory of Evolution by Natural Selection.   (1 mark)

  2. Describe two key principles of natural selection that lead to convergent evolution.   (2 marks)

  3. Provide two examples of convergent evolution, one involving Australian fauna and one non-Australian, explaining how each demonstrates the process of natural selection.   (2 marks)

Show Answers Only

a.   Convergent evolution definition:

→ The process by which unrelated organisms develop similar traits or features as a result of adapting to similar environmental pressures or ecological niches.
 

b.   Key principles that lead to convergent evolution:

→ Natural selection acts on existing variations within populations, favouring traits that enhance survival and reproduction in specific environments.

→ When unrelated organisms face similar environmental challenges, natural selection can lead to the evolution of similar adaptations, even in distantly related species.

→ This process occurs independently in each lineage, resulting in analogous structures or behaviours that serve similar functions but have different evolutionary origins.
 

c.   Australian fauna (example):

→ The similarity between the marsupial Tasmanian tiger (thylacine) and the placental grey wolf is an example of convergent evolution.

→ Despite their distant relationship, both evolved similar body shapes, jaw structures, and striped patterns due to adapting to similar predatory lifestyles. 
 

Non-Australian (example):

→ The similar body shapes of sharks and dolphins is another example of convergent evolution.

→ Though one is a fish and the other a mammal, both have evolved streamlined bodies, dorsal fins, and tail flukes as adaptations for efficient swimming in marine environments.

→ This demonstrates how natural selection can produce similar outcomes in response to comparable environmental pressures.

Show Worked Solution

a.   Convergent evolution definition:

→ The process by which unrelated organisms develop similar traits or features as a result of adapting to similar environmental pressures or ecological niches.
 

b.   Key principles that lead to convergent evolution:

→ Natural selection acts on existing variations within populations, favouring traits that enhance survival and reproduction in specific environments.

→ When unrelated organisms face similar environmental challenges, natural selection can lead to the evolution of similar adaptations, even in distantly related species.

→ This process occurs independently in each lineage, resulting in analogous structures or behaviours that serve similar functions but have different evolutionary origins.
 

c.   Australian fauna (example):

→ The similarity between the marsupial Tasmanian tiger (thylacine) and the placental grey wolf is an example of convergent evolution.

→ Despite their distant relationship, both evolved similar body shapes, jaw structures, and striped patterns due to adapting to similar predatory lifestyles. 
 

Non-Australian (example):

→ The similar body shapes of sharks and dolphins is another example of convergent evolution.

→ Though one is a fish and the other a mammal, both have evolved streamlined bodies, dorsal fins, and tail flukes as adaptations for efficient swimming in marine environments.

→ This demonstrates how natural selection can produce similar outcomes in response to comparable environmental pressures.

BIOLOGY, M3 EQ-Bank 1

  1. Explain the difference between micro-evolution and macro-evolution, highlighting their key characteristics and relationship.   (2 marks)
  2. Provide an example of how microevolutionary changes can accumulate to drive larger evolutionary changes and potentially lead to speciation.   (2 marks)

Show Answers Only

a.   Difference between microevolution and macroevolution:

→ Microevolution refers to small-scale changes in gene frequencies within a population over time, such as changes in colour or size.

→ Macroevolution, on the other hand, involves large-scale changes that lead to the formation of new species or higher taxonomic groups.

→ While both rely on the same mechanics of change, microevolution occurs relatively quickly and can be observed within human timescales while macroevolution typically occurs over much longer periods and is inferred from fossil records.
 

b.   Answers could include one of the following examples.

Evolution of the platypus:

→ Over millions of years, the evolution of the platypus saw small genetic changes accumulate.

→ This process resulted in a combination of reptilian and mammalian features, such as egg-laying and milk production.

→ These gradual changes eventually led to the emergence of a distinct species that occupies a unique ecological niche.
 

Evolution of the horse:

→ Fossil evidence shows the evolution of the horse from a small, multi-toed ancestor to larger, single-toed modern horses.

→ Each small change, such as increases in size or reductions in toe number, represented micro-evolutionary steps.

→ Over millions of years, these accumulated changes resulted in the diverse horse species we see today, adapted to various environments.

Show Worked Solution

a.   Difference between microevolution and macroevolution:

→ Microevolution refers to small-scale changes in gene frequencies within a population over time, such as changes in colour or size.

→ Macroevolution, on the other hand, involves large-scale changes that lead to the formation of new species or higher taxonomic groups.

→ While both rely on the same mechanics of change, microevolution occurs relatively quickly and can be observed within human timescales while macroevolution typically occurs over much longer periods and is inferred from fossil records.
 

b.   Answers could include one of the following examples.

Evolution of the platypus:

→ Over millions of years, the evolution of the platypus saw small genetic changes accumulate.

→ This process resulted in a combination of reptilian and mammalian features, such as egg-laying and milk production.

→ These gradual changes eventually led to the emergence of a distinct species that occupies a unique ecological niche.
 

Evolution of the horse:

→ Fossil evidence shows the evolution of the horse from a small, multi-toed ancestor to larger, single-toed modern horses.

→ Each small change, such as increases in size or reductions in toe number, represented micro-evolutionary steps.

→ Over millions of years, these accumulated changes resulted in the diverse horse species we see today, adapted to various environments.

BIOLOGY, M3 EQ-Bank 6

Many plants in hot climates exhibit leaf droop, where their leaves hang downwards during the hottest parts of the day.

  1. Describe this type of adaptation.   (1 mark)

  2. Provide two reasons why this adaptation might be beneficial for plants in these environments.   (2 marks)

Show Answers Only

a.   Behavioural adaptation.

→ Leaf droop is classified as a behavioural adaptation because it involves a dynamic response to environmental conditions rather than a fixed structural or physiological change.
 

b.   This adaption is beneficial because:

→ it reduces the surface area of the leaf directly exposed to intense sunlight, minimising water loss and protecting the leaf from heat damage.

→ when drooping leaves are arranged vertically, they direct water to the base of the plant where the roots can more efficiently absorb it. This is particularly beneficial in arid environments.

Show Worked Solution

a.   Behavioural adaptation.

→ Leaf droop is classified as a behavioural adaptation because it involves a dynamic response to environmental conditions rather than a fixed structural or physiological change.
 

b.   This adaption is beneficial because:

→ it reduces the surface area of the leaf directly exposed to intense sunlight, minimising water loss and protecting the leaf from heat damage.

→ when drooping leaves are arranged vertically, they direct water to the base of the plant where the roots can more efficiently absorb it. This is particularly beneficial in arid environments.

BIOLOGY, M3 EQ-Bank 3 MC

Consider the following adaptations in Australian organisms:

\(\text{I.}\)   The ability of koalas to detoxify eucalyptus leaves.  
\(\text{II.}\)   The migration of bogong moths to alpine areas in summer.  
\(\text{III.}\)   The spines on an echidna.  
\(\text{IV.}\)   The camouflage patterns on a leaf-tailed gecko.  

 
Which combination correctly identifies one of each type of adaptation (structural, physiological, and behavioural)?

  1. \(\text{I, II,}\) and \(\text{III}\)
  2. \(\text{I, II,}\) and \(\text{IV}\)
  3. \(\text{I, III,}\) and \(\text{IV}\)
  4. \(\text{II, III,}\) and \(\text{IV}\)
Show Answers Only

\(D\)

Show Worked Solution

Consider each statement:

\(\text{I.}\) Physiological adaptation. The ability of koalas to detoxify eucalyptus leaves involves internal metabolic processes.

\(\text{II.}\) Behavioral adaptation. The migration of bogong moths is a seasonal behavior that helps them survive and reproduce.

\(\text{III.}\) Structural adaptation. The spines on an echidna are physical features that provide protection.

\(\text{IV.}\) Structural adaptation. The camouflage patterns on a leaf-tailed gecko are physical characteristics, though they can change slightly which could be considered physiological.

\(\Rightarrow D\)

CHEMISTRY, M3 EQ-Bank 8 MC

Which statement best explains how molecular orientation affects the rate of a chemical reaction according to collision theory?

  1. Reactant molecules must collide with enough energy, but the orientation of the molecules is irrelevant.
  2. Correct orientation only affects reactions that involve more than two reactant molecules.
  3. Incorrect molecular orientation increases the activation energy required for the reaction to proceed.
  4. Even with sufficient energy, reactants must collide in the correct orientation to allow bonds to break and form.
Show Answers Only

\(D\)

Show Worked Solution

→ For a reaction to occur, not only must reactants collide with sufficient energy, but they must also collide in the correct orientation to break existing bonds and form new ones.

→ Even if the reactants have enough energy, incorrect orientation can prevent a successful reaction.

\(\Rightarrow D\)

CHEMISTRY, M3 EQ-Bank 14

A student conducted an experiment to investigate how the concentration of hydrochloric acid affects the rate of its reaction with magnesium ribbon. They measured the volume of hydrogen gas produced at regular intervals in reactions using 1.0 M, 2.0 M, and 3.0 M hydrochloric acid, keeping other variables constant.

  1. Explain how the concentration of hydrochloric acid influences the rate of reaction with magnesium, using collision theory.   (2 marks)
  1. Describe how the student could modify the experiment to investigate the effect of temperature on the reaction rate.   (2 marks)
  1. Identify and explain one advantage of a student using digital technologies such as a gas pressure sensor to collect or analyse data from the experiment.   (2 marks)
Show Answers Only

a.   \(\ce{[HCl]} influence on the rate of reaction:

→ As the concentration increases, the number of acid particles in a given volume also increases.

→ This leads to more frequent collisions between hydrochloric acid molecules and the magnesium surface.

→ As a result, a higher concentration of hydrochloric acid increases the chance of successful collisions, which increases the reaction rate and causes hydrogen gas to be produced more quickly.
 

b.   Experiment modifications:

→ To investigate the effect of temperature on the reaction rate, the student could modify the experiment by conducting the reaction at different temperatures while keeping the concentration of hydrochloric acid constant.

→ They could use a water bath or hot plate to control the temperature for each trial. For example, the student could perform the reaction at 20°C, 30°C, and 40°C, then measure and compare the volume of hydrogen gas produced over time at each temperature.
 

c.   Advantage of digital technologies:

→ Using a gas pressure sensor in the experiment allows for continuous and precise data collection without human intervention.

→ This reduces the chances of human error when measuring the volume of gas produced manually at intervals, leading to more accurate and reliable results.

→ Additionally, the sensor can automatically record data over time, providing detailed information about the reaction rate that can be easily analysed using digital tools such as graphing software.

Show Worked Solution

a.   \(\ce{[HCl]} influence on the rate of reaction:

→ As the concentration increases, the number of acid particles in a given volume also increases.

→ This leads to more frequent collisions between hydrochloric acid molecules and the magnesium surface.

→ As a result, a higher concentration of hydrochloric acid increases the chance of successful collisions, which increases the reaction rate and causes hydrogen gas to be produced more quickly.
 

b.   Experiment modifications:

→ To investigate the effect of temperature on the reaction rate, the student could modify the experiment by conducting the reaction at different temperatures while keeping the concentration of hydrochloric acid constant.

→ They could use a water bath or hot plate to control the temperature for each trial. For example, the student could perform the reaction at 20°C, 30°C, and 40°C, then measure and compare the volume of hydrogen gas produced over time at each temperature.
 

c.   Advantage of digital technologies:

→ Using a gas pressure sensor in the experiment allows for continuous and precise data collection without human intervention.

→ This reduces the chances of human error when measuring the volume of gas produced manually at intervals, leading to more accurate and reliable results.

→ Additionally, the sensor can automatically record data over time, providing detailed information about the reaction rate that can be easily analysed using digital tools such as graphing software.

CHEMISTRY, M3 EQ-Bank 13

A certain chemical reaction begins with a high reaction rate but over time this rate of reaction slows until the reaction is complete.

Explain this statement using collision theory.   (3 marks)

Show Answers Only

→ At the start of the reaction, there is a high concentration of reactant molecules, which increases the frequency of collisions between them. According to collision theory, more frequent and effective collisions lead to a higher reaction rate.

→ As the reaction progresses, the concentration of reactants decreases, leading to fewer collisions. With fewer successful collisions occurring over time, the reaction rate slows down.

→ Eventually, when most or all of the reactants are used up, the reaction reaches completion, and the rate drops to zero.

Show Worked Solution

→ At the start of the reaction, there is a high concentration of reactant molecules, which increases the frequency of collisions between them. According to collision theory, more frequent and effective collisions lead to a higher reaction rate.

→ As the reaction progresses, the concentration of reactants decreases, leading to fewer collisions. With fewer successful collisions occurring over time, the reaction rate slows down.

→ Eventually, when most or all of the reactants are used up, the reaction reaches completion, and the rate drops to zero.

BIOLOGY, M3 EQ-Bank 6

"The prickly pear cactus, introduced to Australia in the 1800s, became a significant ecological problem before being brought under control."

Describe two significant changes to the ecosystem caused by the prickly pear invasion and the control method used to manage its population. In your answer, discuss the effectiveness of this control measure and its ecological implications.   (4 marks)

Show Answers Only

→ The prickly pear outcompeted native vegetation, forming dense thickets that reduced grazing land for livestock and native animals.

→ It also altered habitat structures, displacing native fauna and changing local biodiversity patterns. eg. it harboured pest species like rabbits.

→ To control the prickly pear population, scientists introduced the Cactoblastis moth, whose larvae feed exclusively on prickly pear species.

→ This biological control method proved remarkably effective, with the moths feeding almost exclusively on the prickly pear. As prickly pear numbers reduced, the moths also became rarer.

→ This control measure rapidly reduced prickly pear populations to manageable levels within a decade, restoring native ecosystems and millions of hectares of land for agricultural use.

→ This demonstrates the potential power and risks of biological control agents, as the moth’s effectiveness in Australia led to its introduction in other parts of the world, where it has sometimes become a pest itself.

Show Worked Solution

→ The prickly pear outcompeted native vegetation, forming dense thickets that reduced grazing land for livestock and native animals.

→ It also altered habitat structures, displacing native fauna and changing local biodiversity patterns. eg. it harboured pest species like rabbits.

→ To control the prickly pear population, scientists introduced the Cactoblastis moth, whose larvae feed exclusively on prickly pear species.

→ This biological control method proved remarkably effective, with the moths feeding almost exclusively on the prickly pear. As prickly pear numbers reduced, the moths also became rarer.

→ This control measure rapidly reduced prickly pear populations to manageable levels within a decade, restoring native ecosystems and millions of hectares of land for agricultural use.

→ This demonstrates the potential power and risks of biological control agents, as the moth’s effectiveness in Australia led to its introduction in other parts of the world, where it has sometimes become a pest itself.

BIOLOGY, M3 EQ-Bank 1

Describe two biotic factors that could act as selection pressures in a grassland ecosystem.

For each factor, briefly explain how it might influence the organisms living in that environment.   (4 marks)

Show Answers Only

Predation:

→ Predation by herbivores like grazing animals could favour plants with defensive structures or compounds.

→ eg. the Acacia tree, common in Australian grasslands, has developed long, sharp thorns as a defensive structure against herbivores.
 

Competition:

→ Competition for resources such as light or nutrients might select for faster-growing or taller plant species. 

→ Gum trees can grow to impressive heights which gives them an advantage in capturing sunlight. 
 

Parasites:

→ Parasites causing fungal infections, could drive the evolution of resistance mechanisms in both plants and animals.

→ Ticks are a parasite that can attach to the skin of animals like kangaroos and cattle, feeding on their blood and transmitting diseases. Animals with tick resistance will have a survival advantage.

Show Worked Solution

Answers could include two of the following.

Predation:

→ Predation by herbivores like grazing animals could favour plants with defensive structures or compounds.

→ eg. the Acacia tree, common in Australian grasslands, has developed long, sharp thorns as a defensive structure against herbivores.
 

Competition:

→ Competition for resources such as light or nutrients might select for faster-growing or taller plant species. 

→ Gum trees can grow to impressive heights which gives them an advantage in capturing sunlight.
 

Parasites:

→ Parasites causing fungal infections, could drive the evolution of resistance mechanisms in both plants and animals.

→ Ticks are a parasite that can attach to the skin of animals like kangaroos and cattle, feeding on their blood and transmitting diseases. Animals with tick resistance will have a survival advantage.

CHEMISTRY, M3 EQ-Bank 3 MC

When molecules react, the final rate of a chemical reaction is determined by which of the following factors?

  1. The proportion of collisions where the number of molecules are keep the same.
  2. The proportion of collisions where molecules have the correct orientation
  3. The proportion of collisions where atoms are destroyed
  4. The proportion of collisions where molecules form larger structures
Show Answers Only

\(B\)

Show Worked Solution

→ For a reaction to occur, it is not enough for molecules to simply collide.

→ They must collide with the correct orientation for bonds to break and new ones to form. Even if the energy is sufficient, an incorrect orientation will not result in a successful reaction.

→ Therefore, the rate of a chemical reaction is largely determined by the proportion collisions that occur with the proper orientation between reacting molecules.

\(\Rightarrow B\)

CHEMISTRY, M3 EQ-Bank 10

A student conducted a series of  investigations where 8.50 g of sodium carbonate was reacted with excess nitric acid \(\ce{(HNO3)}\) at a temperature of 25°C and 100 kPa. The volume of carbon dioxide gas produced was measured at regular intervals during each investigation. In experiment A, sodium carbonate was provided as large crystals, and in experiment B, it was supplied in powdered form.

Both reactions produced 1.988 L of \(\ce{CO2(g)}\) however experiment B finished reacting before experiment A finished reacting.

  1. Explain why experiment B had a faster rate of reaction than experiment A.   (1 mark)
  1. Using the volume of \(\ce{CO2(g)}\) produced, calculate the maximum mass of carbon dioxide produced in the reaction.   (3 marks)
  1. Explain why both experiments produced in the same volume of carbon dioxide.   (1 mark)
Show Answers Only

a.   Experiment B faster than experiment A:

→ In experiment B, the surface area of the sodium carbonate was greater than in experiment A due to it being in a powdered form.

→ Thus, there are a greater number of collisions able to occur in experiment B, leading to a greater number of successful collisions.

→ Overall this allows the rate of reaction of experiment B to be greater than that of experiment A.

b.    \(3.52\ \text{g}\)

c.   Reasons why same volume \(\ce{CO2}\) produced:

→ Both experiments used the same amount of sodium carbonate reacting with excess hydrochloric acid.

→ The maximum amount of carbon dioxide produced is dependent on how much sodium carbonate reacted.

→ As the initial mass of sodium carbonate is the same in both reaction and both reactions went until completion, the volume of carbon dioxide will be the same despite the different rates of reaction between experiment A and B.

Show Worked Solution

a.   Experiment B faster than experiment A:

→ In experiment B, the surface area of the sodium carbonate was greater than in experiment A due to it being in a powdered form.

→ Thus, there are a greater number of collisions able to occur in experiment B, leading to a greater number of successful collisions.

→ Overall this allows the rate of reaction of experiment B to be greater than that of experiment A.
 

b.   The maximum volume of carbon dioxide produced is 1.988 L.

→ At SLC (standard laboratory conditions), the 1 mole of gas takes up 24.79 L.

→ \(\ce{n(CO2(g))}= \dfrac{1.988}{24.79} = 0.08\ \text{mol}\)

→ \(\ce{m(CO2(g))} = n \times MM = 0.08 \times 44.01 =3.52\ \text{g}\)
 

c.   Reasons why same volume \(\ce{CO2}\) produced:

→ Both experiments used the same amount of sodium carbonate reacting with excess hydrochloric acid.

→ The maximum amount of carbon dioxide produced is dependent on how much sodium carbonate reacted.

→ As the initial mass of sodium carbonate is the same in both reaction and both reactions went until completion, the volume of carbon dioxide will be the same despite the different rates of reaction between experiment A and B.

Functions, EXT1 F1 EQ-Bank 4

Let  \(f(x)=x^2-4 x+3\)  for  \(x \leqslant 2\).

  1. State the domain of  \(y=f^{-1}(x)\).  (1 mark)

  2. What is the equation of  \(y=f^{-1}(x)\) ?  (3 marks)

  3. For the restricted domain, sketch the function and the inverse function on the same number plane below.
  4. Clearly identify all axis intercepts.  (2 marks)

Show Answers Only

a.   \(f(x)=(x-1)(x-3)\ \Rightarrow \ \text{Axis of symmetry at}\ \ x=2. \)

\(f(2)=-1\)

\(\text{Range}\ f(x): \  y \geqslant -1\ \Rightarrow \ \text{Domain}\ f^{-1}(x): \  x \geqslant -1 \)
 

b.   \(y=2-\sqrt{x+1}\)

c.   \(f(x)\ \text{intercepts:}\ (1,0), (0,3) \)

\(f^{-1}(x)\ \text{intercepts:}\ (3,0), (0,1) \)

Show Worked Solution

a.   \(f(x)=(x-1)(x-3)\ \Rightarrow \ \text{Axis of symmetry at}\ \ x=2. \)

\(f(2)=-1\)

\(\text{Range}\ f(x): \  y \geqslant -1\ \Rightarrow \ \text{Domain}\ f^{-1}(x): \  x \geqslant -1 \)
 

b.   \(\text{Inverse: swap}\ x ↔ y \)

\(x\) \(=y^2-4y+3\)  
\(x\) \(=(y-2)^2-1\)  
\(x+1\) \(=(y-2)^2\)  
\(y-2\) \(=\pm \sqrt{x+1} \)  
\(y\) \(=2 \pm \sqrt{x+1} \)  
\(y\) \(=2-\sqrt{x+1}\ \ \ \ (\text{Range}\ f^{-1}(x): \ y \leqslant 2) \)  

 
c.   \(f(x)\ \text{intercepts:}\ (1,0), (0,3) \)

\(f^{-1}(x)\ \text{intercepts:}\ (3,0), (0,1) \)

Calculus, EXT1 C1 EQ-Bank 5 MC

Simplify  \(\dfrac{\sqrt{1+\tan ^2 \theta} \sqrt{1-\sin ^2 \theta}}{\sqrt{\operatorname{cosec}^2 \theta-1}}, \operatorname{cosec}^2 \theta \neq 1\)

  1. \(\tan \theta\)
  2. \(\cot \theta\)
  3. \(\sec \theta\)
  4. \(1\)
Show Answers Only

\(A\)

Show Worked Solution
  \(\dfrac{\sqrt{1+\tan ^2 \theta} \sqrt{1-\sin ^2 \theta}}{\sqrt{\operatorname{cosec}^2 \theta-1}} \) \(=\dfrac{\sqrt{\sec ^2 \theta} \sqrt{\cos ^2 \theta}}{\sqrt{\cot ^2 \theta}} \)
    \( =\dfrac{\sec \theta\, \cos \theta}{\cot \theta}\)
    \( =\dfrac{1}{\cot \theta}\)
    \( =\tan \theta\)

 
\(\Rightarrow A\)

BIOLOGY, M2 EQ-Bank 6

Describe the pulmonary circuit and the changes in blood composition as it circulates through this system.   (4 marks)

Show Answers Only

→ The pulmonary circuit is the part of the circulatory system that carries deoxygenated blood from the heart to the lungs for oxygenation and then returns oxygenated blood back to the heart

→ Deoxygenated blood entering the lungs has low oxygen levels and high carbon dioxide levels. As it passes through the alveolar capillaries, oxygen diffuses into the blood while carbon dioxide diffuses out.

→ This process results in blood leaving the lungs with higher oxygen content and lower carbon dioxide levels.

→ Additionally, the blood slightly cools as it passes through the lungs due to its proximity to the air in the alveoli and the evaporation of water vapour during exhalation.

→ The pH of the blood also slightly increases as carbon dioxide (which forms carbonic acid in blood) is removed.

Show Worked Solution

→ The pulmonary circuit is the part of the circulatory system that carries deoxygenated blood from the heart to the lungs for oxygenation and then returns oxygenated blood back to the heart

→ Deoxygenated blood entering the lungs has low oxygen levels and high carbon dioxide levels. As it passes through the alveolar capillaries, oxygen diffuses into the blood while carbon dioxide diffuses out.

→ This process results in blood leaving the lungs with higher oxygen content and lower carbon dioxide levels.

→ Additionally, the blood slightly cools as it passes through the lungs due to its proximity to the air in the alveoli and the evaporation of water vapour during exhalation.

→ The pH of the blood also slightly increases as carbon dioxide (which forms carbonic acid in blood) is removed.

BIOLOGY, M2 EQ-Bank 5

Compare and contrast the structure of red blood cells (erythrocytes) and platelets (thrombocytes), explaining how their unique features contribute to their efficiency in performing their respective functions in the circulatory system.   (4 marks)

Show Answers Only

→ Red blood cells are biconcave discs lacking a nucleus, which maximises their capacity to carry haemoglobin and increases their flexibility to squeeze through narrow capillaries, enhancing oxygen transport efficiency.

→ Platelets are flat, irregularly-shaped cell fragments that lack both organelles and nuclei. When blood vessel damage occurs, they change shape and aggregate to form a blood clot and stop bleeding.

→ The absence of a nucleus in red blood cells allows for more haemoglobin but limits their lifespan to about 120 days, while platelets typically survive for 8-10 days.

→ Red blood cells’ structure optimises oxygen carrying capacity and delivery, while platelets’ structure facilitates rapid response to vascular damage. 

→ Both red blood cells and platelets have high surface area to volume ratios which allows them to efficiently carry out their primary functions.

Show Worked Solution

→ Red blood cells are biconcave discs lacking a nucleus, which maximises their capacity to carry haemoglobin and increases their flexibility to squeeze through narrow capillaries, enhancing oxygen transport efficiency.

→ Platelets are flat, irregularly-shaped cell fragments that lack both organelles and nuclei. When blood vessel damage occurs, they change shape and aggregate to form a blood clot and stop bleeding.

→ The absence of a nucleus in red blood cells allows for more haemoglobin but limits their lifespan to about 120 days, while platelets typically survive for 8-10 days.

→ Red blood cells’ structure optimises oxygen carrying capacity and delivery, while platelets’ structure facilitates rapid response to vascular damage. 

→ Both red blood cells and platelets have high surface area to volume ratios which allows them to efficiently carry out their primary functions.

BIOLOGY, M2 EQ-Bank 3

The diagram below shows features that are observed in cross-sections of three types of blood vessel.
 

   

  1. Complete the diagram by identifying the type of blood vessel identified by \(\text{A}\) and \(\text{C}\).   (2 marks)
  2. Describe how the structural features of \(\text{B}\) contribute to its role in the circulatory system.   (2 marks)
Show Answers Only

a.   

 
b.   \(\text{B}\) is an artery.

→ Arteries have thick, elastic walls with multiple layers of smooth muscle, allowing them to withstand and maintain the high pressure of blood pumped directly from the heart.

→ This elasticity also enables arteries to expand and recoil with each heartbeat, helping to propel blood forward in a phenomenon known as the “pulse.”

→ Additionally, the smooth inner lining of arteries reduces friction, facilitating efficient blood flow and preventing clot formation.

Show Worked Solution

a.   

 
b.   \(\text{B}\) is an artery.

→ Arteries have thick, elastic walls with multiple layers of smooth muscle, allowing them to withstand and maintain the high pressure of blood pumped directly from the heart.

→ This elasticity also enables arteries to expand and recoil with each heartbeat, helping to propel blood forward in a phenomenon known as the “pulse.”

→ Additionally, the smooth inner lining of arteries reduces friction, facilitating efficient blood flow and preventing clot formation.

CHEMISTRY, M3 EQ-Bank 28v4

A student stirs 2.50 g of silver (I) nitrate powder into 100.0 mL of 1.50 mol L\(^{-1}\) sodium chloride solution until it is fully dissolved. A reaction occurs and a precipitate appears.

  1. Write a balanced chemical equation for the reaction.   (1 mark)
  2. Calculate the theoretical mass of precipitate that will be formed.   (4 marks)

    The student weighed a piece of filter paper, filtered out the precipitate and dried it thoroughly in an incubator. The final precipitate mass was higher than predicted in (b).
  3. Identify one scientific reason why the precipitate mass was too high and suggest an improvement to the experimental method which would eliminate this error.   (2 marks)
Show Answers Only

a.    \(\ce{AgNO3(aq) + NaCl(aq) -> AgCl(s) + NaNO3(aq)}\)

b.    \(2.11 \text{ g}\)

c.    One possible reason for the higher mass could be the presence of excess solution in the filter paper or incomplete drying. An improvement could be to ensure the precipitate is thoroughly rinsed with distilled water to remove soluble impurities and dried completely in the incubator before weighing.

Show Worked Solution

a.    \(\ce{AgNO3(aq) + NaCl(aq) -> AgCl(s) + NaNO3(aq)}\)

b.    \(\ce{n(AgNO3) = \frac{m}{M} = \frac{2.50}{107.9 + 14.01 + 16.00 \times 3} = \frac{2.50}{169.91} = 0.01471 \text{ mol}}\)

\(\ce{n(NaCl) = c \times V = 1.50 \times 0.100 = 0.150 \text{ mol}}\)

\(\ce{AgNO3} \text{ is the limiting reagent}\)

\(\ce{n(AgCl) = n(AgNO3) = 0.01471 \text{ mol}}\)

\(\ce{m(AgCl) = n \times M = 0.01471 \times (107.9 + 35.45) = 0.01471 \times 143.35 = 2.11 \text{ g}}\)

c.    One possible reason for the higher mass could be the presence of excess solution in the filter paper or incomplete drying. An improvement could be to ensure the precipitate is thoroughly rinsed with distilled water to remove soluble impurities and dried completely in the incubator before weighing.

CHEMISTRY, M3 EQ-Bank 28v2

A student stirs 3.50 g of copper (II) nitrate powder into 150.0 mL of 1.50 mol L\(^{-1}\) sodium chloride solution until it is fully dissolved. A reaction occurs and a precipitate appears.

  1. Write a balanced chemical equation for the reaction.   (1 mark)
  2. Calculate the theoretical mass of precipitate that will be formed.   (4 marks)

    The student weighed a piece of filter paper, filtered out the precipitate and dried it thoroughly in an incubator. The final precipitate mass was higher than predicted in (b).
  3. Identify one scientific reason why the precipitate mass was too high and suggest an improvement to the experimental method which would eliminate this error.   (2 marks)
Show Answers Only

a.    \(\ce{Cu(NO3)2(aq) + 2NaCl(aq) -> CuCl2(s) + 2NaNO3(aq)}\)

b.    \(2.51 \text{ g}\)

c.    One possible reason for the higher mass could be the presence of excess solution in the filter paper or incomplete drying. An improvement could be to ensure the precipitate is thoroughly rinsed with distilled water to remove soluble impurities and dried completely in the incubator before weighing.

Show Worked Solution

a.    \(\ce{Cu(NO3)2(aq) + 2NaCl(aq) -> CuCl2(s) + 2NaNO3(aq)}\)

b.    \(\ce{n(Cu(NO3)2) = \frac{m}{M} = \frac{3.50}{63.55 + 2 \times (14.01 + 16.00 \times 3)} = \frac{3.50}{187.57} = 0.01866 \text{ mol}}\)

\(\ce{n(NaCl) = c \times V = 1.50 \times 0.150 = 0.225 \text{ mol}}\)

\(\ce{Cu(NO3)2} \text{ is the limiting reagent}\)

\(\ce{n(CuCl2) = n(Cu(NO3)2) = 0.01866 \text{ mol}}\)

\(\ce{m(CuCl2) = n \times M = 0.01866 \times (63.55 + 2 \times 35.45) = 0.01866 \times 134.45 = 2.51 \text{ g}}\)

c.    One possible reason for the higher mass could be the presence of excess solution in the filter paper or incomplete drying. An improvement could be to ensure the precipitate is thoroughly rinsed with distilled water to remove soluble impurities and dried completely in the incubator before weighing.

CHEMISTRY, M4 EQ-Bank 5

The chemical equation for the complete combustion of ethane  \(\ce{(C2H6)}\)  is given below:

\(\ce{2C2H6(g) + 7O2(g) -> 4CO2(g) + 6H2O(l)}\)

The structural formula for ethane and standard bond energies for provided for you.

\begin{array} {|c|c|}
\hline Bond & Enthalpy \text{ (kJ mol}^{-1})  \\     
\hline \ce{C-C} & 348 \\
\hline \ce{O-O} & 146 \\
\hline \ce{O=O} & 495 \\
\hline \ce{C-O} & 358 \\
\hline \ce{C=O} & 799 \\
\hline \ce{C-H} & 413 \\
\hline \ce{H-O} & 463 \\
\hline \end{array}

Using the bond energies provided, calculate the enthalpy for the complete combustion of one mole of ethane.   (3 marks)

Show Answers Only

\(-1415.5\ \text{kJ mol}^{-1}\)

Show Worked Solution
\(\Delta H\) \(=\Sigma\,{\text{bonds broken}}-\Sigma\,{\text{bonds formed}}\)  
  \(=((12 \times 413) + (2 \times 348) + (7 \times 495))-((8 \times 799) + (12 \times 463))\)  
  \(=9117-11948\)  
  \(=-2831\)  (for two moles of ethane, as per the equation)  

 
→ \(\Delta H\) for the combustion of one mole of ethane is \(-1415.5 \text{ kJ mol}^{-1}\)

BIOLOGY, M2 EQ-Bank 2

Describe the nature and significance of plasma in the circulatory system. In your answer, include two crucial functions that plasma performs in the body and how a deficiency or imbalance in plasma components might affect overall health.   (4 marks)

Show Answers Only

→ Plasma is the liquid component of blood, making up about 55% of its volume, and consists primarily of water with dissolved proteins, glucose, clotting factors, hormones, and electrolytes.

→ One crucial function of plasma is transport, carrying nutrients, hormones, and waste products throughout the body, fuelling cells and removing metabolic waste.

→ Another vital role of plasma is in maintaining blood pressure and volume, with plasma proteins keeping fluid within blood vessels.

→ A deficiency or imbalance in plasma components can reduce the ability to form blood clots and lead to excessive bleeding.

→ A decrease in plasma proteins can result in edema where fluid leaks from blood vessels into surrounding tissues, causing swelling.

Show Worked Solution

→ Plasma is the liquid component of blood, making up about 55% of its volume, and consists primarily of water with dissolved proteins, glucose, clotting factors, hormones, and electrolytes.

→ One crucial function of plasma is transport, carrying nutrients, hormones, and waste products throughout the body, fuelling cells and removing metabolic waste.

→ Another vital role of plasma is in maintaining blood pressure and volume, with plasma proteins keeping fluid within blood vessels.

→ A deficiency or imbalance in plasma components can reduce the ability to form blood clots and lead to excessive bleeding.

→ A decrease in plasma proteins can result in edema where fluid leaks from blood vessels into surrounding tissues, causing swelling.

BIOLOGY, M2 EQ-Bank 1 MC

Which of the following is a characteristic of an open circulatory system?

  1. Blood is always contained within blood vessels.
  2. It is typically found in larger, more complex animals.
  3. Hemolymph bathes organs directly in body cavities.
  4. It allows for rapid, high-pressure blood flow.
Show Answers Only

\(C\)

Show Worked Solution

→ In an open circulatory system, the circulatory fluid (hemolymph) is not always confined within blood vessels but instead bathes organs directly in body cavities. 

\(\Rightarrow C\)

BIOLOGY, M2 EQ-Bank 10 MC

Which of the following statements about phloem transport in plants is correct?

  1. Sap in the phloem always moves from areas of high sugar concentration to areas of low sugar concentration.
  2. The direction of sap movement in the phloem is solely determined by gravity.
  3. Moving sap through the phloem requires energy input and can occur both up and down the plant.
  4. The rate of sap movement in the phloem is constant throughout the day and night.
Show Answers Only

\(C\)

Show Worked Solution

Consider each option.

Option A: Incorrect. While sugar concentration plays a role, phloem transport is more complex and can move against concentration gradients.

Option B: Incorrect. Gravity is not the determining factor as phloem transport can occur both up and down the plant.

Option C: Correct. Phloem transport is an active process requiring energy, and it can move substances bidirectionally based on the plant’s needs.

Option D: Incorrect. The rate of phloem transport varies depending on factors such as photosynthetic activity and the plant’s growth needs.

\(\Rightarrow C\)

BIOLOGY, M2 EQ-Bank 8

The transpiration-cohesion-tension theory provides an explanation for water movement in tall trees.

Describe this theory, including the role of transpiration in this process.   (4 marks)

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→ Transpiration creates a negative water potential at the leaves (tension), driving water movement upwards through the xylem.

→ This process acts like a ‘pull’ force, drawing water from the roots to replace water lost through the leaves.

→ The theory states that this movement also relies critically on cohesion, which refers to the tendency of water molecules to stick together due to hydrogen bonding.

→ This property allows water to form a continuous column in the xylem, enabling it to be pulled upwards without breaking. 

→ This tension, combined with the cohesive properties of water, allows trees to transport water against gravity to great heights. 

Show Worked Solution

→ Transpiration creates a negative water potential at the leaves (tension), driving water movement upwards through the xylem.

→ This process acts like a ‘pull’ force, drawing water from the roots to replace water lost through the leaves.

→ The theory states that this movement also relies critically on cohesion, which refers to the tendency of water molecules to stick together due to hydrogen bonding.

→ This property allows water to form a continuous column in the xylem, enabling it to be pulled upwards without breaking. 

→ This tension, combined with the cohesive properties of water, allows trees to transport water against gravity to great heights. 

BIOLOGY, M2 EQ-Bank 6

Compare and contrast the microscopic structures involved in gas exchange in mammals and plants.

In your answer, describe one structural similarity between these structures that aids in gas exchange and explain one key difference in how these structures function.   (4 marks)

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→ The primary microscopic structure for gas exchange in mammals is the alveolus, while in plants it is the leaf.
 

Structural similarities that aid in gas exchange (include one):

→ Both have a large surface area to volume ratio to maximise gas exchange.

→ Both have thin, moist surfaces to facilitate the diffusion of gases.
 

Two key differences in how these structures function in gas exchange are:

→ Alveoli primarily exchange oxygen and carbon dioxide with blood, while leaves exchange these gases with air in intercellular spaces.

→ Gas exchange in alveoli occurs continuously for respiration, while in leaves it varies with light availability due to its role in photosynthesis.

Show Worked Solution

→ The primary microscopic structure for gas exchange in mammals is the alveolus, while in plants it is the leaf.
 

Structural similarities that aid in gas exchange (include one):

→ Both have a large surface area to volume ratio to maximise gas exchange.

→ Both have thin, moist surfaces to facilitate the diffusion of gases.
 

Two key differences in how these structures function in gas exchange are:

→ Alveoli primarily exchange oxygen and carbon dioxide with blood, while leaves exchange these gases with air in intercellular spaces.

→ Gas exchange in alveoli occurs continuously for respiration, while in leaves it varies with light availability due to its role in photosynthesis.

CHEMISTRY, M4 EQ-Bank 7 MC

The chemical equation for the decomposition of calcium carbonate is shown below

\(\ce{CaCO3(s) -> CO2(g) + CaO(s)}\)

Which of the following best describes the type of reaction given that the bond energy of the reactant is greater than the bond energy of the products.

  1.  An exothermic reaction because energy is absorbed
  2. An exothermic reaction because energy is released
  3. An endothermic reaction because energy is absorbed
  4. An endothermic reaction because energy is released
Show Answers Only

\(C\)

Show Worked Solution

→ \(\Delta H= \Sigma\,\text{bond energies broken}-\Sigma\,\text{bond energies formed}\)

→ If the bond energy of the reactant is greater than the bond energy of the products, then more energy is required to break apart the reactant bonds then being produced in the formation of the product bonds.

→ Hence \(\Delta H\) will be positive as energy is being absorbed.

\(\Rightarrow C\)

BIOLOGY, M2 EQ-Bank 7 MC

Consider the following statements about alveoli in mammals and the internal structure of plant leaves:

\(\text{I.}\)    Both structures have a thin, moist surface to facilitate gas exchange.  
\(\text{II.}\)    Alveoli exchange gases with blood, while leaves exchange gases with air spaces.  
\(\text{III.}\)    Alveoli are specialised for both oxygen uptake and carbon dioxide release,
while leaves are specialised only for oxygen release.		  
\(\text{IV.}\)    Both structures are kept moist to facilitate the diffusion of gases.  

 
Which combination of statements is correct?

  1. \(\text{I}\) and \(\text{II}\) only
  2. \(\text{I, II}\) and \(\text{IV}\) only
  3. \(\text{II, III}\), and \(\text{IV}\) only
  4. \(\text{I, II, III}\) and \(\text{IV}\) only
Show Answers Only

\(B\)

Show Worked Solution

Consider each statement.

\(\text{I:}\) Correct. Both alveoli and the internal structure of plant leaves have a thin, moist surface to facilitate gas exchange.

\(\text{II:}\) Correct. Alveoli exchange gases directly with blood in the surrounding capillaries, while leaves exchange gases with air spaces within their internal structure (intercellular spaces). 

\(\text{III:}\) Incorrect. Both alveoli and leaves are specialised for both oxygen uptake and carbon dioxide release.

\(\text{IV:}\) Correct. Both structures are kept moist to facilitate the diffusion of gases. 

\(\Rightarrow B\)

BIOLOGY, M2 EQ-Bank 5

Explain how the respiratory structures of a terrestrial mammal and a bony fish are adapted to their respective environments.

In your answer, discuss how the structure of each system maximises gas exchange.   (4 marks)

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→ The main respiratory organ in terrestrial mammals is the lungs, while in bony fish it’s the gills.

→ Lungs have a large internal surface area created by millions of alveoli.

→ This highly efficient structure, combined with the diaphragm-driven breathing mechanism, allows for rapid oxygen uptake and carbon dioxide release. This ensures that all cells receive adequate gas exchange despite the lower oxygen content in air compared to water.

→ Gills consist of many thin filaments that spread out in the water to provide a large surface area for gas exchange.

→ Fish are able to take in water through their mouths and force the water over their gills. This creates a consistent one-way flow of oxygen-rich water for gas exchange.

→ Fish use a counter-current flow in their gills to maximise oxygen uptake, which is not necessary in lungs. 

Show Worked Solution

→ The main respiratory organ in terrestrial mammals is the lungs, while in bony fish it’s the gills.

→ Lungs have a large internal surface area created by millions of alveoli.

→ This highly efficient structure, combined with the diaphragm-driven breathing mechanism, allows for rapid oxygen uptake and carbon dioxide release. This ensures that all cells receive adequate gas exchange despite the lower oxygen content in air compared to water.

→ Gills consist of many thin filaments that spread out in the water to provide a large surface area for gas exchange.

→ Fish are able to take in water through their mouths and force the water over their gills. This creates a consistent one-way flow of oxygen-rich water for gas exchange.

→ Fish use a counter-current flow in their gills to maximise oxygen uptake, which is not necessary in lungs.