Edexcel A Level Biology B Paper 1: Advanced Biochemistry, Microbiology and Genetics June 2018 question paper 9BI0/01

The venom from some species of snake contains enzymes that affect the blood clotting process.

Factor Xa is a clotting factor present in human blood.

The table shows the effect of different masses of Factor Xa and snake venom on the time taken for blood to clot.

Describe the effect of snake venom on the time taken for the blood to clot.

State the role of platelets in the blood clotting process.

Which bond is labelled Z ?

Describe how this precursor molecule is modified to produce a tRNA molecule specific for the amino acid proline.

Which of the following base sequences is the mRNA code for proline?

Which of the following base sequences is the DNA code for proline?

The photograph shows an adult mayfly.

Rhithrogena germanica is commonly known as the March brown mayfly.

The classification hierarchy for this mayfly is: Animalia

Arthropoda

Insecta

Ephemeropteroidea

Heptageniidae

Rhithrogena germanica

State the genus of this mayfly.

This mayfly belongs to the phylum Arthropoda.

Which is the order for this mayfly?

Mayflies lay their eggs in water.

The graph shows the effect of water temperature on the percentage of mayfly eggs that hatch.

Explain the effect of temperature on the percentage of mayfly eggs that hatch.

Mayfly eggs hatch into immature insects called nymphs. The nymphs live in the water and develop to form adult mayflies.

The photograph shows a mayfly nymph.

Compare and contrast the structure of the gas exchange system of the mayfly nymph with the adult mayfly.

Mitochondria can be extracted from liver cells.

In order to monitor the purification of a sample of mitochondria, a protein concentration: enzyme activity ratio can be determined.

Describe the structure of a globular protein.

When succinate is converted into fumarate, succinate is

Explain the role of the Krebs cycle.

This sample of mitochondria had an absorbance of 0.28 when the protein concentration was measured.

Determine the protein concentration of this sample of mitochondria.

Determine the initial rate of enzyme activity to obtain the protein: enzyme activity ratio for this sample of mitochondria.

Leigh syndrome is a genetic disorder inherited from the mother. The mother carries genes for the disorder in her mitochondrial DNA.

Draw and label a mitochondrion.

Scientists have developed a technique for producing ‘three-parent’ babies.

This ensures that a mother with Leigh syndrome will not pass on the genes for this disorder to her baby.

The technique involves:

● removing the nucleus from the ovum of the mother

● removing the nucleus from the ovum of a donor female to produce an enucleated ovum

● inserting the nucleus from the ovum of the mother into the enucleated donor ovum

● fertilising this ovum with the sperm of the father to produce a zygote

● implanting the resulting embryo into the uterus of the mother.

The ‘three-parent’ baby produced by this technique will inherit mitochondrial DNA from the

Explain the importance of DNA replication during the development of this zygote into a blastocyst.

During the development of active immunity, macrophages present antigens to T helper cells.

Describe how macrophages present antigens to T helper cells.

In an investigation into clonal selection, macrophages and T cells were isolated from two strains of guinea pig, strain 2 and strain 13.

The macrophages from each strain of guinea pig were exposed to an antigen and treated with mitomycin.

Mitomycin forms cross links between complementary strands of DNA.

These macrophages were then cultured with T cells from each of the strains of guinea pig for 72 hours.

Radioactive thymidine was included in the culture. This molecule will become incorporated into DNA during DNA replication instead of thymine.

The table shows the results of this investigation.

Explain why the macrophages were treated with mitomycin.

Explain how radioactive thymidine becomes incorporated into the DNA.

Analyse the data to explain the results of this investigation.

Xylem and phloem are involved in transport in plants.

Which row of the table shows some of the substances transported in xylem and phloem?

Describe the differences between the structure of xylem and that of phloem.

Describe the effect of pressure gradient and radius on the velocity of flow within the xylem vessels.

Calculate the percentage increase in the velocity of water flowing through a xylem vessel of radius 20 µ m and a xylem vessel of radius 100 µ m, at a pressure gradient of 17.5 kPa m^–1.

*(c) Double fertilisation in some plants leads to the development of fruits, such as berries.

In an investigation, the rate of flow in xylem during the formation of berries was measured. The rate of flow in the phloem during the formation and ripening of the berries was also measured.

The results are shown in graph 1.

In a second investigation, two plants with berries were exposed to radioactive carbon dioxide (¹⁴C).

After exposure to¹⁴C, the berries were removed from one plant and left on the second plant.

The percentage of¹⁴C remaining in the leaves of each plant was determined during the next 10 hours.

The results are shown in graph 2.

Time after exposure of plants to¹⁴C / hours

Analyse the data to explain the role of double fertilisation, xylem and phloem in the development of the berries.

Salmonella are Gram negative bacteria found in the large intestine of humans.

Which is the correct statement about Salmonella ?

A scientist studied the growth of Salmonella.

Salmonella was isolated from a mixed culture of bacteria, using streak plating onto selective media.

Explain why this is a suitable method for isolating the Salmonella.

The scientist made a broth culture of Salmonella at a concentration of 5 × 10³ cells per cm³.

Ten hours later the concentration of Salmonella was 4 × 10⁶ per cm³.

Calculate the exponential growth rate constant (k) for this culture of Salmonella using the formula

In this calculation, the scientist did not allow for the time that the Salmonella spent in the lag phase.

Explain the effect that this will have on the calculated value for the growth rate constant.

Soya beans are an important crop for the production of food and oil.

In the 2012 to 2013 growing season, production of soya beans was highest in the United States and second highest in Brazil.

The United States produced 93 million tonnes of soya beans from 31 million hectares.

This was 9.4 % more than Brazil produced from 28 million hectares.

Calculate the difference in the yield per hectare of soya beans from these two countries.

Soya beans can be genetically modified to form transgenic plants.

A study of the nutritional content of soya beans from non-transgenic soya bean plants and from transgenic soya beans plants was carried out in two regions of Brazil.

The regions were Ponta Grossa and Londrina.

Tables 1 and 2 show the results of this study.

*(i) Analyse the data to assess the nutritional content of soya beans from transgenic and from non-transgenic soya bean plants grown in these two regions.

The soil in Londrina is more fertile than the soil in Ponta Grossa. Londrina has higher temperatures and rainfall during the growing season.

Explain the differences in the nutritional content of soya beans grown in these two regions.

Explain why this study also analysed the types of fatty acid found in soya beans from transgenic plants and from non-transgenic plants.