The immune system

A student wants to find how effective three antibiotics are for treating a range of bacterial infections.

This is their method:

• Spread bacteria across an agar plate.

• Soak discs with different antibiotics (A, B and C) and place them on the surface of the agar plate.

• Leave the plate to incubate for 5 days.

The student’s results are shown in the diagram.

Antibiotic discs

Which antibiotics are the most and least effective at inhibiting bacteria growth?

Most effective antibiotic A B C

Least effective antibiotic A B C

Explain your answers. Use the diagram.

Suggest two improvements to the method to increase validity of the investigation.

Bacteria are one cause of communicable disease.

Outline the role of the immune system of the human body in defence against disease.

Tuberculosis (TB) is caused by bacteria. The bacteria usually attack the lungs.

It is estimated that 8.7 million people develop TB worldwide each year.

1.1 million of these people are estimated to have HIV.

Calculate the percentage of people who develop TB worldwide each year who are estimated to have HIV.

Infection with HIV makes you more likely to develop TB.

State one reason why having HIV makes you more likely to develop TB.

Antibiotics are developed to kill bacteria.

Bacteria have appeared that antibiotics can not kill.

Explain how bacteria could have evolved to become antibiotic resistant.

Use ideas about natural selection.

The deaths in one country from different diseases were measured over a 40-year period.

Lifestyle and living conditions in this country changed during the 40 years of the study.

The graph shows the number of deaths per 100 000 of the population for each disease.

The diseases can be grouped into communicable and non-communicable diseases. The graph shows the trends of these two different types of disease over the 40-year period.

Complete the sentences explaining these trends shown in the graph.

Communicable diseases have........

Non-communicable diseases have........

Suggest how lifestyle and living conditions in this country might have changed to cause the trends shown in the graph.

To calculate the death rate in a given year, the following formula is used:

In 1972, the population was 55 million. The death rate from coronary heart disease was 28 deaths per 100 000 people.

Calculate the number of deaths from coronary heart disease in 1972.

The immune system provides a defence against bacterial diseases like TB (tuberculosis).

Part of this defence involves the production of antibodies.

Describe how antibodies help defend the body. Use ideas about antigens in your answer.

What does a vaccination contain and why does it protect the body from infection?

Vaccinations contain........

Vaccinations protect the body because........

What do white blood cells produce to defend the body against tuberculosis?

A Antibodies

B Antigens

C Plasma

D Platelets

What do antibodies bind to when they defend the body?

A Antigens

B Platelets

C Red blood cells

D White blood cells

HIV is a virus that causes AIDS.

HIV infects human cells by inserting genes into the cells. The human cells then copy the genes.

In which part of a human cell are HIV genes copied?

chloroplast cytoplasm mitochondria nucleus

In the laboratory, scientists have used gene technology to completely remove HIV genes from infected cells.

Explain how removing HIV genes could affect the spread of HIV.

Suggest why some people are concerned about the use of gene technology in HIV treatment.

The Human Genome Project mapped the human genome.

Write down what is meant by the term genome.

Knowledge of the human genome could identify the genes affected by HIV.

Write down two ways knowledge of the human genome could help with the treatment of HIV.

*(d) Some countries have set up centres where a person is counselled and tested for HIV.

The aim is to reduce new infections by 50%.

Describe how HIV is transmitted and how these centres can contribute to reducing the spread of HIV.

HIV invades white blood cells stopping them working.

Describe the role of white blood cells in the defence against disease.

HIV is a virus that causes AIDS.

Some countries have set up centres where a person is counselled and tested for HIV.

The aim is to reduce new infections by 50%.

Write down two types of testing that can be done to identify someone with HIV.

Humans who contract HIV do not die from the virus. Instead they die from AIDS-related diseases such as tuberculosis (TB).

HIV infects human cells by inserting genes into the cells. The human cells then copy the genes.

TB is caused by bacteria that infect the lungs.

Explain why a person with HIV is more likely to die from TB than a person without HIV.

Use ideas about the immune system in your answer.

HIV can be transmitted during unprotected sexual intercourse.

Name one method of contraception and explain why it prevents the transmission of HIV.

Name of method of contraception........

Why it prevents the transmission of HIV........

Scientists are trying to develop a vaccine against HIV.

Explain how a vaccine could protect people against HIV.

Which type of medication can be used to treat people who already have HIV?

The diagram shows a virus.

Which structure A, B, C or D is the antigen when the virus invades a host?