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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
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\(D\)

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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
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`C`

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

`=>C`

BIOLOGY, M7 2014 HSC 22b

Drinking water contaminated with dissolved lead (a heavy metal) can cause a serious disease.

Classify this disease as either infectious or non-infectious. Justify your answer.   (2 marks)

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“

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→ This disease is non-infectious as it is not caused by a pathogen and therefore cannot be transferred from host to host.

→ It can only be obtained through digestion of lead.

BIOLOGY, M8 2020 HSC 27

Exposure to arsenic in drinking water has been associated with the onset of many diseases. The World Health Organisation recommends arsenic levels in drinking water should be below 10 `mu`g L-1 .

An epidemiological study involving 58 406 young adults was conducted over an 11-year period in one country to investigate young-adult mortality due to chronic exposure to arsenic in local drinking water. Each individual's average exposure and cumulative exposure to arsenic over the time of the study were calculated. Age, sex, education and socioeconomic status were taken into account during the analysis of the results.

The graphs show survival rates for males and females over the 11-year period associated with different average levels of exposure to arsenic in drinking water.
 

  1. Identify TWO features of the method used that contributed to the validity of this study.   (2 marks)

  2. The hypothesis put forward was that exposure to arsenic in drinking water increases mortality in young adults.
  3. Discuss the data presented in the graphs in relation to this hypothesis.   (4 marks)

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a.   Successful answers should include two of the following:

→ The identification of the age and sex of participants

→  Socioeconomic status 

→  Arsenic exposure

→  Large sample size

→  The length of the study period
 

b.   Consider the less than 90 `mu`g L-1 group:

→  The survival rate for both males and females was highest in this “control” group. This is despite the group being exposed to more arsenic than recommended by WHO.

→  In both males and females, increased exposure to arsenic led to lower survival rates.

→  This gradual survival decrease is best seen in males.

→  In females, all doses over 90 `mu`g L-1 lead to similar survival decrease, suggesting other factors, such as a gene or diet, are interacting with the dosage of arsenic.

→ Over the 11 year period, survival progressively declined, supporting the hypothesis.

→  It is important to note, however, that despite the large sample size and time period the study was conducted, survival only dropped by 0.1%.

Show Worked Solution

a.   Successful answers should include two of the following:

→ The identification of the age and sex of participants

→  Socioeconomic status 

→  Arsenic exposure

→  Large sample size

→  The length of the study period
 

b.   Consider the less than 90 `mu`g L-1 group:

→  The survival rate for both males and females was highest in this “control” group. This is despite the group being exposed to more arsenic than recommended by WHO.

→  In both males and females, increased exposure to arsenic led to lower survival rates.

→  This gradual survival decrease is best seen in males.

→  In females, all doses over 90 `mu`g L-1 lead to similar survival decrease, suggesting other factors, such as a gene or diet, are interacting with the dosage of arsenic.

→ Over the 11 year period, survival progressively declined, supporting the hypothesis.

→  It is important to note, however, that despite the large sample size and time period the study was conducted, survival only dropped by 0.1%.

BIOLOGY, M8 2021 HSC 1 MC

A patient felt tired, weak and had a swollen neck. After following the doctor's advice to eat more foods containing iodised salt, her symptoms disappeared.

What was the most likely cause of the patient's symptoms?

  1. Cancer
  2. Genetic disorder
  3. Nutritional deficiency
  4. Environmental exposure
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`C`

Show Worked Solution

Since iodised salt made symptoms disappear, the patient most likely had a deficiency of iodine.

`=>C`