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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)

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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, M4 EQ-Bank 3

Consider a grassland ecosystem with a population of rabbits, foxes, and various grass species.

  1. Describe one example of predation in this ecosystem.   (1 mark)
  2. Explain two ways in which competition might occur between the rabbits.   (2 marks)
  3. Evaluate how the removal of foxes might affect both the rabbit population and the grass species.   (1 mark)
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a.   → Predation occurs when foxes hunt and eat rabbits.
 

b.   Competition among rabbits could result from (choose two):

→ limited resources such as food or water

→ suitable burrow sites

→ mating partners
 

c.   Removing foxes:

→ could lead to an increase in the rabbit population.

→ this growing population might then overgraze the grass species, potentially causing a decline in grass biodiversity and altering the ecosystem’s structure.

Show Worked Solution

a.   → Predation occurs when foxes hunt and eat rabbits.
 

b.   Competition among rabbits could result from (choose two):

→ limited resources such as food or water

→ suitable burrow sites

→ mating partners
 

c.   Removing foxes:

→ could lead to an increase in the rabbit population.

→ this growing population might then overgraze the grass species, potentially causing a decline in grass biodiversity and altering the ecosystem’s structure.

BIOLOGY, M4 EQ-Bank 1

Explain the concept of a trophic relationship and evaluate its significance within an ecosystem's functioning.   (3 marks)

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→ A trophic relationship refers to the feeding connections between organisms in an ecosystem, essentially describing who eats whom.

→ This relationship forms the basis of energy transfer within an ecosystem, as energy flows from primary producers (like plants) through various levels of consumers.

→ Trophic relationships are crucial in maintaining the balance and structure of ecosystems, influencing population sizes, species interactions, and nutrient cycling.

→ Understanding these relationships helps ecologists predict how changes in one species’ population can affect others throughout the food web, making it a key concept in ecosystem management.

Show Worked Solution

→ A trophic relationship refers to the feeding connections between organisms in an ecosystem, essentially describing who eats whom.

→ This relationship forms the basis of energy transfer within an ecosystem, as energy flows from primary producers (like plants) through various levels of consumers.

→ Trophic relationships are crucial in maintaining the balance and structure of ecosystems, influencing population sizes, species interactions, and nutrient cycling.

→ Understanding these relationships helps ecologists predict how changes in one species’ population can affect others throughout the food web, making it a key concept in ecosystem management.

BIOLOGY, M4 EQ-Bank 33

Why is it detrimental for a predator to be totally efficient at catching its prey?   (2 marks)

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→ When predators are efficient at hunting and catch too many prey, it leads to a rapid decline in the prey’s population.

→ This can lead to a reduction in available food for the predators, causing their population to decline or their need to migrate somewhere else.

Show Worked Solution

→ When predators are efficient at hunting and catch too many prey, it leads to a rapid decline in the prey’s population.

→ This can lead to a reduction in available food for the predators, causing their population to decline or their need to migrate somewhere else.