Practice Paper 1 (Edexcel IGCSE Biology)

The diagram below shows three different types of virus.

• Virus A is a bacteriophage, which injects its genetic material into bacterial cells
• Virus B is TMV, which infects the cells of certain species of plants, such as tobacco, tomatoes and peppers.
• Virus C is a coronavirus, such as the one that causes the disease Covid-19, and it can infect human cells.

The diagrams are not drawn to scale.

(i) Name two structural features that are universal for all types of virus.

(ii) Suggest why it is necessary for the three types of virus to have differences in their structure.

Another example of a virus pathogen that can infect humans is HIV.

HIV can be spread through exchange of bodily fluids.

State three other ways pathogens can spread between people.

When someone is infected with HIV they can develop a condition called AIDS.

People with AIDS are susceptible to infections by pathogens, and can die from infections that most people without AIDS could recover from easily.

(i) HIV infects the white blood cells of the infected person and stops them from working.

Explain why this might cause people to be more susceptible to infections.

(ii) One way of preventing this from occurring is for people with HIV to take medication to prevent the viruses from replicating.

Explain why this can prevent the infected person from developing AIDS.

The graph below shows an estimation of the number of people worldwide that died from AIDS-related illnesses between the years 1990 and 2020.

(i) Describe the trend of data in the graph.

(ii) Suggest two reasons why the number of AIDS-related deaths has declined in recent years.

Food items can often be spoiled if saprotrophic microorganisms such as mould fungi grow on them.

Describe how a saprotrophic fungus such as mould obtains its food.

A student uses this method to investigate ways of preventing peas from being spoiled.

• Place three peas in each of three test tubes as shown in the diagram
• Cover the peas in test tube A with water and keep at 37 °C
• Cover the peas in test tube B with water and keep at 4 °C
• Cover the peas in test tube C with vinegar, which is a weak acid, and keep at 37 °C
• Leave the peas for 24 hours

The student observes the level of cloudiness of the solution to determine how spoiled the peas have become. The level of cloudiness can be used as a measure of fungal growth.

The table shows the student’s results.

(i) Suggest a problem with using the level of cloudiness of the solution to determine how spoiled the peas have become.

(ii) Explain the appearance of the peas in water at 4 °C.

(iii) Explain the appearance of the peas in vinegar at 37 °C.

Separate: Biology Only

State the meaning of the term stem cell.

Separate: Biology Only

Name two sources of stem cells.

Separate: Biology Only

Describe how stem cells can be used in medicine. Include an example in your answer.

The photograph shows a small animal called a woodlouse.

JMK, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons

Woodlice often live under pieces of dead wood in dark, humid conditions.

Design an investigation to find out if light intensity affects the speed at which woodlice move.

Include experimental details in your answer and write in full sentences.

Separate: Biology Only

The diagram shows a nephron of a kidney, with some of the structures labelled.

(i) From which structure are substances forced out of the blood by ultrafiltration?

(ii) From which structure is glucose reabsorbed into the blood by selective reabsorption?

Separate: Biology Only

In homeostasis, the kidney is involved in the control of blood concentration.

(i) State the name for the control of blood concentration.

(ii) Another function carried out by the kidney is excretion.

State what is meant by the term excretion.

Separate: Biology Only

Diabetes insipidus is a medical condition in which the body is unable to produce ADH.

Explain how diabetes insipidus affects the control of blood concentration.

Separate: Biology Only

Desmopressin is a drug used to reduce the symptoms of diabetes insipidus.

(i) Suggest what effect the drug would have on the nephron.

(ii) Describe the effects the drug would have on urine production.

The data in the table were collected in Japan during a seven-year study.

Scientists collected data on the age of mothers and whether they smoked during pregnancy.

They also recorded the percentage of the babies that had a low birth mass.

(i) Calculate the percentage of mothers aged 19 years and under who smoked during pregnancy.

(ii) Determine the ratio of non-smokers to smokers used in the study.

Give the ratio as the nearest whole number (n) in the form n:1

A student examines this data and concludes that smoking is the main factor that causes low birth mass.

Use the data and your own biological knowledge to comment on this conclusion.

Separate: Biology Only

Patients with organ failure currently rely on temporary treatments and the use of donor organs for transplant, but scientists believe that it could be possible to improve the treatment for organ failure by growing entire new organs in the lab.

Scientists researching methods that could be used to grow a new heart have been investigating the use of a scaffold developed from the heart of a human or animal donor. A proposed method for this is shown in the image below.

(i) Explain why stem cells are used in this process.

(ii)Suggest why a scaffold is needed for the growth of a new organ in the lab.

(iii) Suggest the practical and ethical considerations that should be taken into account when developing scaffolds from human or animal donors.

Separate: Biology Only

While growing new hearts for transplant is still some years away, growing skin for transplant from stem cells is currently possible.

A study investigated the effect of stem cells on the rate of healing of skin wounds. Stem cells taken from human skin, known as mesenchymal stem cells (MSC), were administered to skin wounds in immune-deficient mice, and the wounds of the MSC-treated mice were monitored alongside identical wounds in a group of control mice.

The results after 12 days of monitoring are shown below.

(i) Suggest why immune-deficient mice were used in the study.

(ii) Explain the purpose of the control group of mice.

(iii) Calculate the percentage difference in wound healing time between the control group of mice and the MSC-treated mice.

A student read the results of the study described in part (b) and concluded that MSCs could be used to grow new skin to treat burn patients.

Evaluate the student's conclusion.