Monitoring & Maintaining Health (OCR GCSE Combined Science A (Gateway): Biology)

Fig. 20.1 is a diagram of an antibody molecule. Antibodies are protein molecules.

The ends of the antibody molecule bind with a particular antigen molecule.

Fig. 20.1

Explain why a different antibody molecule is needed for each antigen.

The graph shows information about the four most common types of cancer in the UK.

Which type of cancer has the largest difference between the percentage of total deaths and the percentage of money spent on research?

Tick (✓) one box.

Treatment for cancer often involves powerful medicines that stop cells dividing all over the body.

Write down the name of the type of cell division that occurs when body cells divide.

Many types of cancer have been linked to certain genes.

Scientists are trying to find ways to change the genes in embryos to reduce the risks of cancer.

(i) What name is given to the process scientists use to change the genes of an organism?

[1]

(ii) Write down one reason why some people disagree with the process given in (c)(i).

[1]

Fanconi anaemia is a genetic disorder. The disorder causes a decrease in the number of platelets in the blood.

Write down one possible symptom of Fanconi anaemia.

Fanconi anaemia also causes a decrease in white blood cells and red blood cells.

The table shows ranges for blood components in people without Fanconi anaemia.

(i) The diagram shows a microscope slide containing blood from a patient.

The volume of blood under the slide is 0.1mm³ and it contains 1000 white blood cells.

Calculate the number of white blood cells per mm³ of blood.

Number = .........................per mm³ [2]

(ii) Does the blood sample provide evidence that the patient has Fanconi anaemia?

Use the table and your answer to part (b)(i) to justify your answer.

[1]

Angina is caused by a problem in the arteries that supply the heart muscle.

Fatty material (cholesterol) builds up in these arteries.

In angina the heart muscle starts to carry out anaerobic respiration.

Explain why this happens.

Use the information in the diagram and your biological knowledge.

Angina is often the first sign of a disease called coronary heart disease (CHD).

The table is used to estimate the risk of getting CHD. The more points a person scores, then the higher the risk of getting CHD.

(i) How many points are scored by smoking 20 cigarettes a day?

[1]

(ii) What is the effect of age on the chance of getting CHD?

[1]

(iii) Here is some information about two people.

Use the table to work out whether Person A or Person B is most likely to develop CHD.

Show how you worked out your answer.

[3]

There are several treatments for coronary heart disease (CHD).

One of these is an operation.

In this operation, doctors insert a metal grid called a stent into the artery.

(i) Look at the diagram.

Why does using a stent help treat CHD?

[2]

(ii) Taking a drug called statins is a treatment for CHD.

The drug is taken every day and lowers the level of cholesterol in a person’s blood.

Suggest one advantage and one disadvantage of taking statins.

Advantage ..................................
Disadvantage ............................

[2]

People with HC are more likely to get heart disease. The diagram shows the heart of a person who has heart disease.

The graph shows the results of a study of men aged 30 to 49. The study measured the cholesterol levels in the blood of the men. It also recorded if the men developed signs of heart disease.

Explain the possible link between cholesterol and heart disease and if this link is supported by the graph.

Use evidence from the diagram and the graph in your answer.

Animals and plants can get different types of diseases.

Look at the list of four diseases.

AIDS

Type 2 diabetes

Crown gall disease

Barley powdery mildew

Write each disease in the correct column of this table.

Sinusitis is an infection that can be caused by bacteria or viruses.

Sinusitis causes a runny nose and bad headaches.

(i) Doctors only give antibiotics to patients with these symptoms if they are sure their illness is caused by bacteria.

Write down two reasons why.

1 .........................................
2 .........................................

[2]

(ii) Look at the graph. It shows the length of time that patients show symptoms of sinusitis.

Doctors usually wait 14 days after infection before giving patients antibiotics for sinusitis.

Use the graph to explain why.

 [2]

Methamphetamine is a drug.

Scientists are investigating the use of antibodies as a treatment to control the negative effects of the drug.

What is an antibody?

Some people get very painful headaches called migraines.

Scientists think that this is caused by a protein in the brain called CGRP.

Levels of the CGRP protein are higher in the brains of people who get migraines.

Doctors are trying to find a treatment to prevent migraines.

They have produced an antibody against the CGRP protein.

Describe how antibodies are usually made in the human body.

The doctors test the antibody treatment on migraine patients.

The patients are divided into two groups:

• One group is given an injection of the antibody

• The second group receives an injection of a placebo.

They record the mean number of days each patient had migraines before and after treatment.

The table shows their results.

(i) Explain why a placebo group is used in drug testing.

 [3]

(ii) Calculate the percentage decrease in migraine days in the patients that had the antibody injection.

Give your answer to 1 decimal place.

Percentage decrease = ............................... %

[3]

Different parts of the body have natural defence mechanisms to stop pathogens infecting the body. These defences include:

• skin

• tears

• secretions from the stomach.

Describe how each defence stops pathogens infecting the body.

A student is ill and is having tests in hospital. His doctors monitor his body temperature frequently.

Explain why it is important to monitor his body temperature frequently.

The doctors took a sample of blood from the student. They looked at the specimen under a light microscope.

This is a picture of what they saw.

From this picture, the doctors decide that the student’s illness is caused by bacteria (labelled X).

(i) Why do the doctors not think that the structures labelled X are viruses?

[1]

(ii) What equipment could the doctors use to get a clearer image to confirm their ideas?

[1]

Two farmers grow barley in their fields.

They both have a problem with barley powdery mildew infecting their crops.

Powdery mildew is caused by a fungus.

Describe how fungal infections can spread and how they enter plant leaves.

The farmers want to prevent their crops from getting powdery mildew.

(i) Explain how burning plants after the barley has been harvested can protect the crops.

[1]

(ii) Explain how growing barley in the fields one year, then wheat the next year can protect the crops.

[2]

The farmers test two different fungicides.

They each grow barley in one of their fields. Each farmer sprays a different fungicide on their field. They then compare the crop yield in the two different fields.

How could you improve the farmers’ experiment?

Explain your answer.

Erythromycin is an antibiotic drug.

What is an antibiotic?

It is important to get the dose of erythromycin right.

Too much erythromycin can be harmful. However, recently some strains of bacteria have developed resistance to low concentrations of erythromycin.

To see how effective erythromycin is, it is tested using bacteria grown on agar plates. This method is used:

• A petri dish is used that has the bacteria growing evenly over the surface.

• A disc of filter paper is soaked in erythromycin.

• The disc is placed on the agar in the centre of the petri dish using sterile forceps.

• The dish is incubated at 37°C.

(i) Why did the scientists incubate the dish at 37°C rather than at higher or lower temperature?

 [2]

(ii) Why is the filter paper disc moved using sterile forceps?

 [1]

(i) The diagram shows the actual size of the dish after incubation.

This table is used to analyse the results of the experiment.

Use the results of the experiment and the table to judge the level of resistance in this strain of bacteria. A ruler has been added to assist with accurate measurements (The area of a circle = π r² and π = 3.14.)

answer= ....................................... mm²[3]

(ii) Suggest any limitations to measuring the level of resistance with this method.

[2]

Erythromycin is usually given to patients in a capsule.

The capsule has lots of small spheres containing the drug.

The walls of the spheres are different thicknesses.

They are made of a carbohydrate polymer.

(i) Explain why the drug is released from the spheres in the small intestine.

 [2]

(ii) The graph shows the levels of erythromycin in the blood when given using this capsule and in a normal tablet.

Explain the shape of the two graphs and why it is better to give erythromycin in capsules.

[6]

Strokes are a type of cardiovascular disease.

One cause of a stroke is an artery in the brain bursting.

(i) When a person has a stroke, why are arteries more at risk of bursting than veins?

 [1]

(i) How are arteries adapted to try and prevent them bursting and causing a stroke?

 [1]

Strokes can have many risk factors.

Scientists are trying to investigate whether the risk of having a stroke is increased by pollution.

They looked at data from 28 different countries, involving six million people.

They looked at the number of people who had a stroke soon after an increase in pollution.

They compared this to the number of people who had a stroke after no increase in pollution.

This formula was used to produce a risk factor:

risk factor = 

The graph shows their results.

(ii) If the risk factor for a pollutant was 1.00, what conclusion could the scientists make?

 [2]

(ii) Which pollutant is least likely to be a risk factor for a stroke?

 [1]

(iii) The risk factors calculated by the scientists are quite small.

However, they still think that pollution is an important factor in strokes.

How did the nature of the data they used help to convince them of this?

[2]

Two farmers grow barley in their fields.

They both have a problem with barley powdery mildew infecting their crops.

Powdery mildew is caused by a fungus.

Describe how fungal infections can spread and how they enter plant leaves.

The farmers want to prevent their crops from getting powdery mildew.

(i) Explain how burning plants after the barley has been harvested can protect the crops.

[1]

(ii) Explain how growing barley in the fields one year, then wheat the next year can protect the crops.

[2]

The farmers test two different fungicides.

They each grow barley in one of their fields. Each farmer sprays a different fungicide on their field. They then compare the crop yield in the two different fields.

How could you improve the farmers’ experiment?

Explain your answer.