Biology

This chart illustrates three correlation patterns indicating the influence of genes and environment on different traits in individuals.
What does the data show about how genes and family environment affect the three traits?

Cholera is an acute diarrhoeal infection caused by the bacterium Vibrio cholerae. Humans are infected when they consume food or water that is contaminated with the bacterium.
Outline THREE strategies that could prevent the spread of cholera.

Outline a benefit and a limitation of using pharmaceuticals such as antibiotics to treat infectious disease.

The following diagram shows a mutation. Original
What type of mutation is shown in the diagram?

The following diagram shows a mutation.
Outline another type of mutation.

Explain how dialysis compensates for the loss of a function of the kidneys.

Students tested the hypothesis that the number of eggs/young produced was greater in animals using external fertilisation than those using internal fertilisation. They obtained the following data from secondary sources.
What conclusion can be drawn from the data? Justify your answer.

Explain ONE advantage for animals of using external fertilisation.

One of the genes involved in determining the colour of a species of fish has two alleles: yellow and orange. The diagram shows a pedigree chart for the inheritance of colour in the fish.
Use the pedigree chart to explain why the yellow allele is recessive.

Explain how a cross between individuals I and II could be used to determine whether the inheritance of colour in the fish is sex-linked or autosomal.

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 µg 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.

Identify TWO features of the method used that contributed to the validity of this study.

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 µg 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.
The hypothesis put forward was that exposure to arsenic in drinking water increases mortality in young adults.
Discuss the data presented in the graphs in relation to this hypothesis.

A student drew a diagram to model part of the process of meiosis.
Explain the misunderstanding of meiosis shown in this model.

Explain the effect of meiosis on genetic variation.

Explain how TWO processes that affect the gene pool of populations can lead to evolution.

Explain the impact that genetic technologies have had on the management of both infectious and non-infectious diseases.

Outline how in humans, maintenance of temperature is different to the way that glucose is controlled.

The levels of glucose, insulin and glucagon were measured in the plasma of 24 healthy adults at intervals over a 5-hour period. After 1 hour at rest the patients ate a large carbohydrate meal. The results are shown.
Use the data provided to explain how blood glucose is controlled in the body.

Use the information provided in Diagram 1 to explain why the rabies virus cannot be classified as a cellular pathogen.

Post exposure prophylaxis (PEP) is given to patients who have been bitten by a rabid animal. PEP includes an injection of human rabies antibodies (HRIG) as well as injections of a rabies vaccine at 0, 3, 7 and 14 days after exposure to the virus. The following graphs show a generalised response to rabies infection without and with PEP.
Explain how PEP prevents rabies developing after infection with the virus. Support your answer with reference to the information and data provided throughout Question 32.

After infection the virus reproduces in muscle cells near the bite site and in the central nervous system. This requires the single-stranded rabies RNA to be transcribed, translated and replicated in the cytoplasm of host cells. These processes are shown in Diagram 2. Use the information provided in Diagrams 1 and 2 to explain the role of viral RNA polymerase in the reproduction of the virus.

Rabies is a disease that can affect all mammals and is caused by the rabies virus. It is transmitted by the bite of an infected animal. Without treatment it almost always results in death.
Use the information provided to identify TWO features of the rabies infection that facilitate transmission of the pathogen to a new host.

Which of the following is an example of a non-infectious disease?
A. Polio caused by a virus
B. Cholera caused by a bacterium
C. Wheat rust caused by a fungus
D. Haemophilia caused by a gene mutation