Communicable disease

This question is about genetics.

Explain why different genes are made from different lengths of DNA.

Describe why the human population produces approximately 50% female and 50% male babies.

In 2018, a scientist claimed to have genetically modified two human embryos.

Suggest why genetic modification of human embryos is illegal in most countries.

The scientist claimed that the embryos were genetically modified to have a faulty CCR5 gene.

The CCR5 gene codes for a protein that allows HIV to enter cells.

The genetic modification may have caused the embryos to be protected against AIDS.

Suggest how the embryos were genetically modified to make the CCR5 gene faulty.

Suggest what type of cell has the CCR5 protein in its cell membrane.

What type of drug is used to treat HIV?

Chlamydia, HIV and human papillomavirus (HPV) are sexually transmitted diseases (STDs).

Which other disease is sexually transmitted?

Tick (✓) one box.

Flu

Gonorrhoea

Malaria

Measles

Students were asked to estimate the percentage risk of a person becoming infected with different STDs.

The estimate was compared to the actual percentage risk of infection.

Figure 7 shows the results.

The students estimated that the risk of HIV infection was 60%.

Plot the students’ estimated risk of HIV infection on Figure 7.

Which STD in Figure 7 shows the greatest actual risk?

Calculate the difference between the estimated risk and the actual risk of becoming infected with chlamydia.

What conclusion can be made about the estimated risk of infection compared to the actual risk of infection with STDs?

Name one type of contraception that can control the spread of chlamydia.

Patients with HPV infections are at increased risk of cancer.

Suggest what effect HPV has on human DNA.

This question is about health.

Some pathogens cause food poisoning.

Explain how the stomach is adapted to prevent food poisoning.

Different types of disease may interact.

Suggest one type of disease that may be triggered by infection with human papillomavirus (HPV).

Chlamydia, HIV and HPV are sexually transmitted diseases (STDs).

Chlamydia is caused by the same type of microorganism as gonorrhoea.

Suggest how chlamydia infections are treated.

One symptom of chlamydia infection is damage of the uterus lining.

Which two hormones are involved in maintaining the uterus lining?

Students were asked to estimate the percentage risk of a person becoming infected with different STDs.

` The estimate was compared to the actual percentage risk of infection.

Figure 8 shows the results.

Figure 8

Why is the data in Figure 8 plotted as a bar chart and not as a line graph?

The difference between the estimated risk and the actual risk is not the same for each STD.

Suggest two reasons why.

Explain how only some types of contraception reduce the spread of STDs.

Explain why patients with late-stage HIV infection or AIDS are likely to become very ill from other infections.

The electromagnetic spectrum is made up of waves with different wavelengths and frequencies.

Give the type of electromagnetic wave with the lowest frequency.

A wave has a wavelength of 2.5 km and a velocity of 300 000 000 m/s

Calculate the frequency of the wave.

Figure 4 shows equipment that is used to investigate the emission of infrared radiation from different colours of surface.

The four hollow metal cubes are each painted a different colour.

The cubes can be filled with hot water before the lid is put on.

Describe a method to investigate which colour of surface emits infrared radiation at the greatest rate.

Which colour of surface will emit infrared radiation at the greatest rate?

Tick (✓) one box.

It is important to identify people at airports who may have infectious diseases, such as measles.

Explain how cameras that detect the rate of infrared emission can identify people with infectious diseases such as measles.

HIV infection can prevent the body’s immune system from destroying pathogens.

Explain the roles of white blood cells when a pathogen enters the body.

Name the type of drug that can be used to treat HIV.

Describe how AIDS is different from HIV infection.