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BIOLOGY, M8 EQ-Bank 2

  1. Provide an example of a genetic non-infectious disease and how develops at the genetic level.   (1 mark)

  2. Describe TWO major effects of the disease on the human body and why these occur.   (2 marks)

Show Answers Only

a.   Answers could include one of the following:

Cystic Fibrosis

→ Cystic fibrosis develops when a person inherits two faulty copies of the CFTR gene (one from each parent), resulting in defective chloride channels in cell membranes.
  

Huntington’s Disease

→ Huntington’s disease is caused by inheriting a dominant mutated copy of the HTT gene, resulting in the production of abnormal huntingtin protein.
 

b.  Answers could include one of the following:

Cystic Fibrosis

→ The defective chloride channels cause mucus to build up in the lungs, leading to frequent chest infections and breathing difficulties because bacteria become trapped in the airways.

→ The same mucus also blocks pancreatic ducts, preventing digestive enzymes from reaching the intestines, which results in poor nutrient absorption and growth problems.
  

Huntington’s Disease

→ The abnormal protein accumulates in brain cells, causing progressive death of neurons that control movement, leading to uncontrolled jerking and twitching movements.

→ The protein buildup also affects regions of the brain controlling cognitive function, resulting in progressive memory loss and personality changes as these neural networks deteriorate

Show Worked Solution

a.   Answers could include one of the following:

Cystic Fibrosis

→ Cystic fibrosis develops when a person inherits two faulty copies of the CFTR gene (one from each parent), resulting in defective chloride channels in cell membranes.
 

Huntington’s Disease

→ Huntington’s disease is caused by inheriting a dominant mutated copy of the HTT gene, resulting in the production of abnormal huntingtin protein.
 

b.  Answers could include one of the following:

Cystic Fibrosis

→ The defective chloride channels cause mucus to build up in the lungs, leading to frequent chest infections and breathing difficulties because bacteria become trapped in the airways.

→ The same mucus also blocks pancreatic ducts, preventing digestive enzymes from reaching the intestines, which results in poor nutrient absorption and growth problems.
 

Huntington’s Disease

→ The abnormal protein accumulates in brain cells, causing progressive death of neurons that control movement, leading to uncontrolled jerking and twitching movements.

→ The protein buildup also affects regions of the brain controlling cognitive function, resulting in progressive memory loss and personality changes as these neural networks deteriorate

BIOLOGY, M8 2023 HSC 25c

The normal Huntingtin protein has 10–26 repeats of CAG. In Huntington's disease there are 37–80 repeats. This leads to an alteration in the structure of the protein. The graph shows the relationship between the age of onset of Huntington's disease and the number of CAG repeats.
 

Explain the relationship between the number of CAG repeats and the age of onset of Huntington's disease.  (2 marks)

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→ The graph shows that as the number of CAG repeats is increased, the age of the onset of Huntington’s decreases.

→ For example, someone that has 40 repeats will experience the onset of Huntington’s at 60 years old, but someone with 120 repeats will experience symptoms and/or exhibit signs shortly after their birth.

Show Worked Solution

→ The graph shows that as the number of CAG repeats is increased, the age of the onset of Huntington’s decreases.

→ For example, someone that has 40 repeats will experience the onset of Huntington’s at 60 years old, but someone with 120 repeats will experience symptoms and/or exhibit signs shortly after their birth.

♦ Mean mark 49%.

BIOLOGY, M8 2023 HSC 14 MC

Minamata Disease is caused by regular consumption of contaminated fish and shellfish. The symptoms include numbness in the hands and feet, muscle weakness, and damage to vision, hearing and speech.

Pellagra is a disease which causes delusions or mental confusion, diarrhoea, weakness and loss of appetite caused by insufficient levels of iron and niacin.

Wildervanck Syndrome is a condition that affects the bones in the neck, the eyes and the ears, and occurs primarily in females.

Given the information above, which row in the table correctly identifies the classification of these diseases?
 

  Minamata Disease Pellagra Wildervanck Syndrome
A.   Genetic Nutritional Environmental
B.   Genetic Environmental Nutritional
C.   Environmental Genetic Nutritional
D.   Environmental Nutritional Genetic
Show Answers Only

\(D\)

Show Worked Solution

By Elimination:

→ Minamata is caused by consumption of contaminated seafood and is therefore environmental, not genetic (Eliminate A and B).

→ Pellagra is caused by insufficient iron and niacin levels, which are a mineral and a vitamin respectively. It is therefore a nutritional disease and not genetic (Eliminate C).

→ As Wildervanck Syndrome occurs primarily in females, there cannot be 100% certainty it is genetic. However, with all other options eliminated, it can be assumed to be the case here.

\(\Rightarrow D\)

BIOLOGY, M8 EQ-Bank 1 MC

What is the main focus of the study of epidemiology?

  1. Skin diseases
  2. Changes in the characteristics of a species
  3. Factors involved in the occurrence, prevalence and spread of disease
  4. How the body maintains its functions in response to variations in the environment
Show Answers Only

`C`

Show Worked Solution

→ The nature of an epidemiological study reveals evidence for factors involved in disease incidence and mortality.

`=>C`

BIOLOGY, M7 2019 HSC 33d

Alzheimer's disease causes destruction of brain tissue, dementia and eventually death.

The diagram shows the effect of Alzheimer's disease on the brain.

Amyloid beta protein is produced in the human brain throughout life. In people with Alzheimer's disease, it accumulates in excessive amounts.

The gene with the greatest known effect on the risk of developing late-onset Alzheimer's disease is called APOE. It is found on chromosome 19.

The APOE gene has multiple alleles, including e2, e3 and e4 .

The table shows the risk of developing Alzheimer's disease for various APOE genotypes compared to average risk in the population.
 

  

A large epidemiological study was conducted. It used historical data to investigate the association between Herpes simplex virus (HSV) infection and dementia. Dementia is caused by a variety of brain illnesses. Alzheimer's disease is the most common cause of dementia.

The study used the records of 8362 patients with HSV infection and 25086 randomly selected sex- and age-matched control patients without HSV infection. Some of the patients with HSV had been treated with antiviral medication.

The graph below shows some results of the study.
 

Diseases are classified as infectious or non-infectious.

Evaluate whether Alzheimer's disease should be classified as an infectious disease or a non-infectious disease. In your answer, include reference to the information and data provided above.   (8 marks)

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Infectious vs non-infection disease classification

→ Infectious diseases are a result of pathogens, biological agents of disease, which transmit disease between hosts. A pathogen is a cause of a certain disease if it meets the criteria in Koch’s postulates.

→ The study above shows the association between HSV and Alzheimer’s.

→ The study is conducted over a long period and includes a large and controlled sample size, so the assumption can be made that the findings are valid.

→ HSV is an infectious disease as it is caused by a pathogen, the virus Herpes simplex.

→ The findings show that treating HSV with antiviral medication also reduces the risk of developing Alzheimer’s.

→ This may mean that Alzheimer’s is also a virus and therefore an infectious disease.
 

→ Non-infectious diseases are not contagious and do not spread from person to person. They are a result of environmental factors or genetic conditions.

→ Alzheimer’s is the result of a build-up of the amyloid beta protein, which is produced in the brain.

→ The synthesis of this protein is regulated by the APOE gene. This gene also has various alleles, each of which in different combinations can increase or decrease a individual’s risk of developing Alzheimer’s.

→ This indicates that Alzheimer’s is a non-infectious disease, as it is not transmitted by a pathogen. Rather, it results from a natural build up of a specific protein, which may be accelerated or reduced based on genotype.
 

Conclusion

→ From the information provided it is not possible to accurately classify Alzheimer’s as either an infectious or non-infectious disease.

→ There is evidence to support that the risk of developing Alzheimer’s can be linked to both antiviral and virus traits as well as genotype.

Show Worked Solution

Infectious vs non-infection disease classification

→ Infectious diseases are a result of pathogens, biological agents of disease, which transmit disease between hosts. A pathogen is a cause of a certain disease if it meets the criteria in Koch’s postulates.

→ The study above shows the association between HSV and Alzheimer’s.

→ The study is conducted over a long period and includes a large and controlled sample size, so the assumption can be made that the findings are valid.

→ HSV is an infectious disease as it is caused by a pathogen, the virus Herpes simplex.

→ The findings show that treating HSV with antiviral medication also reduces the risk of developing Alzheimer’s.

→ This may mean that Alzheimer’s is also a virus and therefore an infectious disease.
 

→ Non-infectious diseases are not contagious and do not spread from person to person. They are a result of environmental factors or genetic conditions.

→ Alzheimer’s is the result of a build-up of the amyloid beta protein, which is produced in the brain.

→ The synthesis of this protein is regulated by the APOE gene. This gene also has various alleles, each of which in different combinations can increase or decrease a individual’s risk of developing Alzheimer’s.

→ This indicates that Alzheimer’s is a non-infectious disease, as it is not transmitted by a pathogen. Rather, it results from a natural build up of a specific protein, which may be accelerated or reduced based on genotype.
 

Conclusion

→ From the information provided it is not possible to accurately classify Alzheimer’s as either an infectious or non-infectious disease.

→ There is evidence to support that the risk of developing Alzheimer’s can be linked to both antiviral and virus traits as well as genotype.


♦♦ Mean mark 46%.

BIOLOGY, M8 2019 HSC 1 MC

Which of the following is an example of a non-infectious disease?

  1. Polio caused by a virus
  2. Cholera caused by a bacterium
  3. Wheat rust caused by a fungus
  4. Haemophilia caused by a gene mutation
Show Answers Only

`D`

Show Worked Solution

→ Virus, bacteria and fungi are all pathogens; disease carriers which can be transmitted between hosts.

→ Gene mutations are changes in DNA and cannot be transmitted to others by contact or vectors.

`=>D`

BIOLOGY, M8 2022 HSC 24

Birth defects in humans can be caused by chromosomal abnormalities.

\begin{array}{|c|c|}
\hline
\rule{0pt}{2.5ex}\quad \textit{Maternal} \quad & \textit{Prevalence of}\\
\textit{age} & \textit{chromosomal}\\
\text{(years)} & \textit{abnormalities}\\
\text{} & \rule[-1ex]{0pt}{0pt}\text{(per 1000 births)}\\
\hline \rule{0pt}{2.5ex}20 \rule[-1ex]{0pt}{0pt}& 1.5 \\
\hline \rule{0pt}{2.5ex}30 \rule[-1ex]{0pt}{0pt}& 3 \\
\hline \rule{0pt}{2.5ex}35 \rule[-1ex]{0pt}{0pt}& 8 \\
\hline \rule{0pt}{2.5ex}40 \rule[-1ex]{0pt}{0pt}& 22 \\
\hline \rule{0pt}{2.5ex}45 \rule[-1ex]{0pt}{0pt}& 38 \\
\hline
\end{array}

  1. Draw a suitable graph of the data provided in the table. Include a suitable line of best fit.  (3 marks)
     

  1. Outline the trend shown in the data.  (2 marks)

  2. Explain the cause of a type of chromosomal mutation.  (3 marks)

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a. 

 

b.   Data trend:

→ After 20 years of age, the older a woman is when she gives birth, the chance of her child having a chromosomal abnormality increases exponentially.
 

c.   Cause of chromosomal mutation:

→ Aneuploidy is a chromosomal mutation where the child contains either an extra or a deficit of a chromosome.

→ This is a result of non-disjunction, where in meiosis, chromosomes fail to separate.

→ This can produce a gamete with an extra chromosome (trisomy, 2N+1) or one missing a certain chromosome (monosomy, 2N-1).

→ Down Syndrome (Trisomy 21) is the result of a child containing an extra chromosome 21.
 

Other answers could include

→ Polyploidy, duplications of whole sets of chromosomes (XN).

→ Rearrangement, deletion, insertion, translocation or duplications of sections of a chromosome.

Show Worked Solution

a. 

b.   Data trend:

→ After 20 years of age, the older a woman is when she gives birth, the chance of her child having a chromosomal abnormality increases exponentially.


♦ Mean mark (a) 54%.
Mean mark (b) 56%.

c.   Cause of chromosomal mutation:

→ Aneuploidy is a chromosomal mutation where the child contains either an extra or a deficit of a chromosome.

→ This is a result of non-disjunction, where in meiosis, chromosomes fail to separate.

→ This can produce a gamete with an extra chromosome (trisomy, 2N+1) or one missing a certain chromosome (monosomy, 2N-1).

→ Down Syndrome (Trisomy 21) is the result of a child containing an extra chromosome 21.
 

Other answers could include

→ Polyploidy, duplications of whole sets of chromosomes (XN).

→ Rearrangement, deletion, insertion, translocation or duplications of sections of a chromosome.


♦♦ Mean mark (c) 32%.

BIOLOGY, M8 2021 HSC 19-20 MC

Use the following information to answer Questions 19–20.

Alcohol that is consumed is broken down by the following pathway.
 


 

ALDH is the product of the ALDH gene. The normal allele is ALDH1 but many people have the ALDH2 allele, which is associated with an increased risk of cancer.

Scientists have used mouse models to study the effects of ALDH2. They used wild-type mice with ALDH1 alleles and genetically-engineered mice with one or two copies of the ALDH2 allele.

The mice were given a dose of alcohol and the response was measured. The results are shown.
 

 
Question 19

The ALDH alleles differ in their

  1. genome location.
  2. location in gametes.
  3. effect on phenotype.
  4. amino acid composition.

 
Question 20

What do the data show about the effect of the ALDH2 allele?

  1. Enzyme activity is highest in homozygous mice.
  2. Enzyme activity decreases if ALDH2 is present.
  3. Enzyme activity increases if ALDH2 is present.
  4. Enzyme activity is lowest in wild-type mice.
Show Answers Only

`text{Question 19:}\ C`

`text{Question 20:}\ B`

Show Worked Solution

Question 19

→ The graph depicts that the two alleles (ALDH1 and ALDH2) can produce three different phenotypes

→ i.e. slow, moderate and fast alcohol metabolisation.

`=>C`

♦ Mean mark (Q19) 36%.

Question 20

→ The graph indicates that the ALDH2 / ALDH2 group had the slowest metabolism of alcohol shown by the consistently high levels of acetaldehyde over time, suggesting decreased enzyme activity.

`=>B`

♦ Mean mark (Q20) 41%.