Development of Medicines (Edexcel GCSE Biology)

Microorganisms can be cultured in the laboratory to investigate the effect of antibiotics and disinfectants.

Figure 1 shows the process involved in preparing the culture under aseptic conditions.

Figure 1

(i) The petri dish containing agar shown in Stage 1 has been prepared by heating to 160 °C before it can be used in Stage 2.

Explain why this is a necessary step before preparing the required bacterial cultures. 

(2)

(ii) Identify two other stages in Figure 1 which show aseptic technique and explain how they ensure preparation of an uncontaminated culture.

(2)

(iii) Explain why the petri dish should not be incubated at a temperature higher than 25 °C in the final stage.

(1)

During the incubation period, bacterial colonies will develop on the agar medium.

State the name of the process by which bacteria reproduce.

Some scientists investigated the effect of two antibiotics (methicillin and penicillin) on the growth of two different bacteria.

They used filter paper discs soaked in antibiotic solution and placed the discs on two agar plates, one had been spread with bacteria A and the other with bacteria B.

The filter paper discs were prepared as follows:

1. Control

2. Penicillin

3. Methicillin

Figure 1 shows the results from the investigation:

Figure 1

(i) Suggest what the paper disc might have been soaked in for the control.

(1)

(ii) Describe and explain the results in Figure 1.

(4)

Scientists at a drug company are working to develop a new pain relief drug.

Figure 1 shows the procedure that the scientists must work through before the new drug can be accepted and distributed to patients world wide.

Figure 1

(i) Outline what is involved in the preclinical tests of the drug.

(2)

(ii) Give the range for the number of volunteers needed to complete all the clinical trials for the new drug.

(1)

(iii) Describe how the clinical trials should be carried out.

(6)

Figure 2 shows the effect of penicillin on the structure of a bacterium.

Figure 2

Explain how the mechanism shown in Figure 2 helps to protect an individual from the harmful effects of the pathogen.

Higher Tier Only

Monoclonal antibodies can be used to determine blood hormone levels.

Pregnancy test strips use monoclonal antibodies.

The hormone HCG is produced in the placenta in pregnant women.

The kidneys excrete HCG.

Figure 1 shows three pregnancy test strips.

Figure 1

(i) Which test strip would belong to a woman who is not pregnant?

(1)

(ii) Pregnancy testing uses monoclonal antibodies.

Give two other uses of monoclonal antibodies. 

(2)

Hepatitis B is an infectious viral disease which infects the liver.

A double-blind trial was carried out to assess the effectiveness of using monoclonal antibodies to treat patients with a hepatitis B infection.

During the trial referred, a number of patients were admitted to the hospital because they felt unwell.

Information about these patients is shown in Figure 2.

Figure 2 

3 000 patients were involved in the trial.

Half the patients (Group A) were given the placebo.

Half the patients (Group B) were given the monoclonal antibody being tested.

(i) Outline how a double-blind trial would be carried out.

(3)

Higher Tier Only

(ii) Explain how injecting a patient, suffering from hepatitis B, with a specific monoclonal antibody will help in their treatment.

(2)

(iii) Using the data in Figure 6, calculate the number of patients admitted to hospital with hepatitis B during the trial. 

(2)

Obesity increases the risk of a person developing cardiovascular disease.

Losing weight can reduce the risk of this disease occurring.

Explain why exercise can cause weight loss.

Figure 1 shows a gastric band fitted to a stomach.

Figure 1

Explain how a gastric band helps a person to lose weight.

BMI and waist : hip ratio can be used to find out if a person is obese.

Figure 2 shows some data for two males.

Figure 2

BMI is calculated using the equation:

               BMI = 

(i) Male B has a mass of 72 kg and a height of 1.81 m.

Calculate the BMI of male B.

Give the answer to 3 significant figures.

(3)

(ii) Figure 3 shows the interpretation of BMI values.

           Figure 3

Males with a waist : hip ratio above 0.90 are defined as abdominally obese.

Explain what the BMI and waist : hip ratio for male A shows about his weight distribution.

(2)

Higher Tier Only

A scientist was planning to compare the effectiveness of the antibiotic myxopyronin on two different species of bacteria.

Figure 1 shows the equipment the scientist can use.

Figure 1

(i) Describe how the scientist could determine the effectiveness of myxopyronin on the two species of bacteria.

(2)

(ii) Myxopyronin inhibits bacterial RNA polymerase.

Explain why the antibiotic myxopyronin can be used to treat bacterial infections in humans.

(4)

LDL cholesterol is a type of cholesterol which increases the risk of heart disease.

Statins are drugs used to reduce LDL cholesterol levels.

Figure 1 shows the cholesterol levels in the blood of a man.

He started taking statins at the beginning of February and stopped taking them four months later.

Figure 1

(i) Describe the effect of statins on LDL cholesterol levels in the blood.

Use data from the graph to support your answer.

(2)

(ii) Use evidence from the graph to explain why statins are usually prescribed as life-long medication.

(2)

Which data can be used to calculate the man’s BMI?

Streptococcus mutans is one species of bacteria which causes tooth decay.

A scientist tested the effectiveness of toothpaste at killing this species of bacteria.

The scientist spread the bacteria Streptococcus mutans across an agar jelly plate.

(i) Which word describes the techniques used to prevent contamination of the agar jelly plate?

(1)

(ii) Give two precautions needed to prevent contamination of the agar jelly plate.

(2)

The scientist placed a filter paper disc soaked in toothpaste mixed with saliva (disc A) on one half of the agar jelly plate.

A filter paper disc soaked in only saliva (disc B) was placed on the other half of the agar jelly plate.

The agar jelly plate was kept at 37 °C for 24 hours.

Figure 1 shows the results.

Figure 1

(i) The diameter of the zone of inhibition around disc A is 9 mm.

Calculate the area of this zone of inhibition using the equation πr².

Use a value of 3.14 for π.

Give your answer to 1 decimal place.

(3)

(ii) Give a reason why disc B, soaked in only saliva, was included in this test.

(1)

(iii) Suggest two reasons why this test does not prove that toothpaste kills all bacteria on teeth.

(2)

Before a new toothpaste can be sold, the toothpaste has to be tested on cultured human cells.

Cultured human cells were placed into four identical flasks.

Saliva was added to each flask and a different brand of toothpaste was added to each of the three flasks.

The human cells were left for two hours and the percentage of cells that were healthy was recorded.

Figure 2 shows the results.

Figure 2

Explain the conclusion that can be made from this data.

Figure 1 shows how alcohol consumption increases the risk of developing liver cancer.

Someone who does not drink alcohol has a 1.0 risk of developing liver cancer.

Figure 1

(i) One unit of alcohol contains 8 grams of alcohol.

Calculate the risk of developing liver cancer for someone who consumes 4 units of alcohol a day.

(2)

(ii) Describe how cancer develops in the liver.

(2)

Figure 1 shows the structures in a leaf.

Figure 1

Explain how to structure Z is involved in defence against pathogens.

Chemicals can be extracted from plants.

Some of these chemicals can kill bacteria.

A scientist spread some bacteria on a nutrient agar plate as shown in Figure 2.

Figure 2

(i) What is being shown in Figure 2?

(1)

(ii) Explain why the scientist worked near to a Bunsen burner.

(2)

A scientist spread bacteria onto the surface of two agar plates.

A filter paper disc was placed in the centre of each plate.

Each filter paper disc had been soaked in a different chemical extracted from plants.

The results are shown in Figure 3.

Figure 3

(i) The area of a circle is calculated using πr²

Calculate the area of the zone of inhibition for chemical A.

Use π = 3.14

(2)

(ii) The scientist concluded that chemical A was more effective than chemical B at killing bacteria.

Give two variables the scientist needed to control to make this conclusion valid.

(2)

Some crop plants have been genetically engineered to produce toxic chemicals in their leaves.

Explain one advantage of producing these genetically modified crop plants.

Coronary Heart Disease (CHD) is a major cause of death worldwide.

Describe how CHD develops and the main causes.

Coronary Heart Disease (CHD) is classed as a non-communicable disease.

Suggest what is meant by a non-communicable disease.

Two types of cholesterol in the blood can have a profound impact on a patient’s health; LDL and HDL.

• High levels of LDL are associated with coronary heart disease (CHD).

• High levels of HDL in the blood can reduce levels of LDL.

There are a number of drugs which can be prescribed to increase an individual’s HDL level to reduce their risk of developing CHD.

Scientists monitored the effect of five of these drugs on one person over 10 years, the results are shown in Figure 1 below.

The labelled arrows show when each new treatment was started.

Figure 1

Compare the effectiveness of the treatments in reducing the risk of CHD.

(4)

Statins are a commonly prescribed drug which can reduce an individual’s risk of developing Coronary Heart Disease (CHD).

Discuss the use of statins to prevent CHD.

Bacteria can be cultured within a lab for research purposes. This is a key step in the development of new medicines.

Describe and explain how a scientist should prepare a bacterial culture on a Petri dish.

A scientist tested different antibiotics to determine their effectiveness on a bacterial colony growing on a Petri dish. She soaked small paper discs in different antibiotics and placed them on the Petri dish where the bacterial colony was growing. Paper disc A was not soaked in anything.

The image in Figure 1 shows the results she obtained.

Figure 1

(i) What was the purpose of the scientist testing the effect of disc A?

(1)

(ii) The diameter of the inhibition zone for disc E was measured as 2.1cm.
Calculate the inhibition zone for disc E. Include the correct units in your answer.

Give your answer to 2 decimal places.

Use π = 3.14

(5)

Having a high proportion of body fat can lead to a person becoming obese. People with a BMI over 30 are considered to be obese.

Suggest why BMI is not always an accurate indication of health and body fat levels.

(i) Figure 1 shows the incidence rate of different heart-related health issues compared to their BMI classification.

Figure 1

Use the figures to calculate how many times more likely you would be to have heart failure when severely obese compared to being healthy weight.

Give your answer to 3 significant figures.

(2)

(ii) Explain why someone who is severely obese is more likely to have heart failure than someone who is a healthy weight.

(4)

(iii) There are other risk factors that can contribute to a person developing cardiovascular disease.

Suggest and explain another how one other risk factor can contribute to the development of cardiovascular disease.

(3)

The information in Table 1 below shows some information about two types of treatment for cardiovascular disease.

Table 1

Explain why a patient might opt for a stent rather than bypass surgery to treat cardiovascular disease.

Use information in the table above and your own knowledge in your answer.

Monoclonal antibodies is the term used to describe many identical antibodies made by identical immune cells. These have various uses in medicine and research. 

Number the steps 1-5 in Table 1 below to describe how monoclonal antibodies are produced.

Table 1

Monoclonal antibodies are now routinely used to treat a number of diseases, including Crohn’s disease, which is a condition where parts of the digestive system become inflamed due to a chemical called TNF. TNF is a small protein known as a cytokine, which, when released, trigger an immune response which ultimately leads to inflammation.

(i) Monoclonal antibodies can bind to TNF to inhibit its activity.  Explain how this works to treat the symptoms of Crohn’s disease. 

(2)

(ii) Suggest why the monoclonal antibodies bind to the TNF molecules but not normal body cells.

(2)

Evaluate the use of monoclonal antibodies in treating diseases.

Before medication can be manufactured and sold on a large scale, the drugs go through a rigorous trial process.

(i) Explain why the drugs need to go through a clinical trial process before being given to patients.

(2)

Table 1 below shows the number of drugs that pass through each stage of the clinical trials.

Table 1

(ii) Calculate the percentage decrease of the number of drugs passing through Phase 1 to Phase 2 and those that are approved.

Give your answer to 3 significant figures.

(2)

As with other drugs, antibiotics must go through a multi-step clinical trial process. 

Some researchers are trying to create alternative antibiotics to those currently being mass-produced. One possible source of antibiotics can be found in natural substances that have antimicrobial properties.

The graph in Figure 1 shows the effectiveness of two different types of herbs when used to kill bacteria: coriander and garlic. Also included in the graph is a control substance and a combination of both herbs together.

Figure 1

Describe the effectiveness of using different types of herbs as an antimicrobial substance.

Use figures from the graph in your answer.

The use of natural antimicrobial substances to destroy unwanted bacteria has increased in recent years. Some bacteria have become resistant to commonly used antibiotics, and therefore alternatives such as herbs are being explored. 

Use your knowledge of natural selection to explain why some bacteria are becoming resistant to antibiotics.