Practice Paper 2 (Edexcel IAL Biology)

A student investigated the nutritional content of two food products, A and B, sold as "healthy" snack bars.

The energy values of macronutrients are:

• Carbohydrate: 17 kJ g⁻¹
• Fat: 39 kJ g⁻¹
• Protein: 17 kJ g⁻¹

Using the data in the table, calculate the expected energy content of product B per 100 g. Show your working.

A nutritionist advised that frequent consumption of product B could increase the risk of cardiovascular disease due to its high saturated fat content.

Explain how a diet high in saturated fat can lead to coronary heart disease.

Product A contains fat with a higher proportion of unsaturated fatty acids.

State two structural differences between a saturated and an unsaturated fatty acid.

Which of the following describes the bond formed between glycerol and a fatty acid in product B?

Sucrose was found in product A.

Describe the structure of a sucrose molecule.

The risk of developing cardiovascular disease (CVD) is affected by two groups of factors:

• Lifestyle factors that can be changed

  • Non‐lifestyle factors that cannot be changed.

Methods to reduce the risk of developing CVD include drug treatments and lifestyle changes.

(i) Which row of the table identifies one lifestyle factor and one non‐lifestyle factor?

(ii) Explain why a person might have to take several types of drugs to reduce the risk of CVD.

Nutritional studies have shown that dietary antioxidants can reduce the risk of CVD.

(i) Explain why antioxidants in the diet reduce the risk of CVD.

(ii) Some studies do not assess the nutritional quality of the diet of the participants.

Explain why the results of these studies have to be treated with caution.

(iii) Explain why changes in diet, other than antioxidants, can reduce the risk of CVD.

Stents are used in the treatment of atherosclerosis.

The diagram shows how stents are positioned in a diseased coronary artery.

Explain why a stent is used in the treatment of atherosclerosis in a coronary artery.

Inserting a stent can damage the artery.

This damage can result in stent thrombosis if the blood clotting process is stimulated.

A study looked at the damage caused by two different types of stent, stent A and stent B.

The graph shows the incidence of stent thrombosis found in this study.

(i)In this study, 800 patients had stent A inserted and 400 patients had stent B inserted.

Calculate the difference in the number of patients who developed stent thrombosis three years after inserting the stent.

(ii) State how the formation of a blood clot in the coronary artery could cause the death of the patient.

(iii) Which components of the blood clotting process are enzymes in their active form?

☐ A Prothrombin and thromboplastin only ☐ B Prothrombin and thrombin only ☐ C Prothrombin, thrombin and thromboplastin ☐ D Thrombin and thromboplastin only

(iv) Which components of the blood clotting process are soluble in blood plasma?

(v) Stent B contains a drug to prevent stent thrombosis.

Suggest one type of drug that could be used in stent B.

Cystic fibrosis is an inherited recessive disease caused by mutations in a gene on chromosome 7.

Give the meaning of the term gene.

Explain how mutations result in cystic fibrosis.

Population carrier screening (PCS) is one type of genetic screening.

This involves screening people who want a child to see if they are carriers of genetic disorders.

In one country, the number of babies born with cystic fibrosis went down following the introduction of PCS.

Suggest why the number of babies born with cystic fibrosis went down.

Catalase is an enzyme that breaks down hydrogen peroxide into water and oxygen. A student investigated the effect of the concentration of catalase on the initial rate of this reaction.

Identify the independent variable and the dependent variable in this investigation.

State two variables that should be controlled to ensure that the results are valid. For each variable, describe how it could be controlled.

The table below shows the volume of oxygen produced over 60 seconds using a 5% catalase solution.

Plot a graph of these results and draw a line of best fit

Use your graph to determine the initial rate of reaction.

Suggest an explanation for the rate of reaction between 40 and 60 seconds.

The photograph shows the caterpillar of a moth from Costa Rica.

The caterpillar looks like a pit viper snake. It will try to strike potential predators.

This caterpillar is adapted to its niche.

Complete the table to show the type of adaptations shown by this caterpillar.

The photograph shows an organelle that can be found in caterpillar cells, as seen using a microscope.

(i) State the type of microscope used to view this organelle.

(ii) Describe the function of this organelle.

Rough endoplasmic reticulum is another organelle found in caterpillar cells.

Draw a labelled diagram of rough endoplasmic reticulum.

The diagram shows the nuclei in an ovule of a flowering plant.

Double fertilisation takes place in the ovules.

Describe the events that occur from the time a pollen grain lands on the stigma to the production of a triploid endosperm nucleus and a zygote.

Use the information in the diagram to support your answer.

The photograph shows flowers from a silver trumpet tree in Thailand.

I, J.M.Garg, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons

Flowering plants such as the silver trumpet tree contain several ovules.

Explain how the silver trumpet tree produces seeds that are genetically different from each other.

The photograph shows a titan arum plant (Amorphophallus titanum).

Credits: US Botanic Garden., Public domain, via Wikimedia Commons

This plant is native to Sumatra, Indonesia, and is critically endangered.

There are fewer than 1000 individuals in the wild and 500 in botanical gardens around the world.

Sumatra is described as having a high species richness.

State what is meant by the term species richness.

Seed banks often conserve endangered plants by storing samples of their seeds.

The seeds are dried and then frozen.

Explain the advantages of drying seeds before storage.

Scientists have stated that more than a third of critically endangered plant species cannot be saved from extinction by storing seeds in seed banks.

The titan arum is one of these plants.

This plant flowers once every 10 years and the flowers last for two to three days.

The plant can reproduce asexually or sexually. In order to reproduce sexually it relies on insects to transfer pollen to other titan arum plants.

Scientists are developing ways to conserve this plant without losing genetic diversity.

Some of the suggestions include:

• Grow more plants produced by asexual reproduction in botanical gardens
• Collect pollen when an individual plant flowers and store it in a seed bank
• Create a studbook for the species
• Artificially pollinate plants in the wild and in botanical gardens.

(i) The heterozygosity index can be calculated using an equation.

Write this equation.

(ii) The heterozygosity index of the 500 titan arum plants in botanical gardens was found to be 0.166.

Calculate the number of heterozygotes in this population.

(iii) Discuss the suggestions, proposed by these scientists, for conserving the titan arum.