AS & A Level Biology - 9700 Paper 1 2017 Summer Zone 2

Which organelles are enclosed in a single phospholipid bilayer and contain hydrolytic enzymes?

The DNA of prokaryotes is naked and circular.
Which statement describes how the DNA of eukaryotes differs from that of prokaryotes?

The recently discovered Pandoravirus measures 1000 nm in diameter.
The Mimivirus has a diameter of 400 nm.
What can be detected using a light microscope with a maximum resolution of 0.25 μm?

What are found in chloroplasts and mitochondria?
1. DNA
2. 70S ribosomes
3. mRNA

Boiling the bones and teeth from dead animals can be used to produce a type of glue. The glue is formed from the collagen fibres present in bones and teeth. Which statement describes the changes to collagen that occur when the glue is produced?

What describes the primary structure of a protein?

The diagrams show four monosaccharides with the formula $C_6H_{12}O_6$.
Which diagram shows $\alpha$-glucose?

Complete digestion of polysaccharides requires all the glycosidic bonds between the monomers to be broken.
Amylase only breaks $\alpha$-1,4 glycosidic bonds.
Which row shows how completely amylase can digest molecules of cellulose, amylopectin or amylose?
[Table_1]

The diagram shows the results of tests on four solutions containing biological molecules. Which shows the solution that contains only starch and protein?

The enzyme invertase catalyses the breakdown of sucrose to glucose and fructose.
Three different enzyme inhibitors of invertase X, Y and Z were investigated. The percentage inhibition of invertase was measured at different concentrations of inhibitor.
The graph shows the result of the investigation.
Which are valid conclusions from these results?
1. The higher the concentration of inhibitor X, the less sucrose is broken down.
2. The production of glucose and fructose using inhibitor Y is higher than when inhibitor Z is used.
3. The production of glucose and fructose at an inhibitor concentration of 2 arbitrary units is lower than at an inhibitor concentration of 4 arbitrary units, for all inhibitors.

The following statements are about enzymes.
1. Folding of an enzyme molecule causes the formation of the active site.
2. The shape of the active site changes to enable the substrate to bind.
3. Temporary bonds hold the substrate in the active site.
4. More enzyme-substrate complexes are formed at the optimum temperature.
Which statements are correct for the induced fit hypothesis?

How is the Michaelis-Menten constant ($K_m$) used?

Proteins in the cell surface membranes of human cells and mouse cells were labelled with fluorescent dyes. The human cells were labelled with a red dye and the mouse cells were labelled with a green dye. A human cell and a mouse cell were then fused to form a hybrid cell.
At first the different dyes remained separate. After 40 minutes the two dyes were evenly distributed in the hybrid cell surface membrane.
What explains this observation?

The diagram shows a plant cell.
The plant cell is put into a solution with a water potential less negative than the cell contents.
What will happen to the appearance of the cell?

The diagram shows the fluid mosaic model of membrane structure:
Which molecules in the membrane are identical?

The photomicrograph shows a stage of mitosis.
What would be correct for the next stage in mitosis?
[Table_1]

The diagram shows part of the organisation of a DNA molecule and the associated histones. Which statement about the features labelled P, Q and R during prophase of mitosis is correct?

The bacterium Escherichia coli divides once every 50 minutes at 36°C.
E. coli were grown on a medium containing only heavy nitrogen, $^{15}N,$ until all of the bacterial DNA contained heavy nitrogen (0 minutes).
Some of the bacteria were moved from a heavy nitrogen medium and cultured in a medium with only light nitrogen, $^{14}N$.
Some bacteria were collected after each of three generations. Their DNA was extracted and centrifuged.
Hybrid DNA contains heavy and light nitrogen.
The diagram shows the possible positions (upper, middle and lower) of the bands of DNA. The actual positions of bands in the first two samples are shown.

Which proportion of the DNA of the sample taken at 150 minutes will be at the upper position?

Different tissues in a plant were supplied with a radioactively labelled substance to identify which tissues were actively synthesising mRNA.
Which radioactively labelled substances would be most suitable for this experiment?

Electron micrographs may show large numbers of ribosomes forming chains along mRNA molecules.
What is the advantage of this arrangement, compared to when ribosomes appear singly on the mRNA?

Which row is correct for adenine? [Table_1]

The graph shows the loss of mass in a potted plant due to transpiration.

What could have occurred at point X on the graph?

Which row is correct for a phloem sieve tube element?
[Table_1: showing cell surface membrane, cytoplasm, nucleus, and 80S ribosomes with indicators ✔ and ✗ for presence or absence]

An aphid, such as a greenfly, uses a tubular mouthpart called a stylet to feed on nutrients in the plant. It inserts the stylet through the surface of a stem or leaf. When a stylet is cut near the aphid’s head, leaving the stylet in the plant, a liquid with a low water potential continues to flow out of the plant. Which statement explains this?

Which statement correctly describes transport pathways in dicotyledonous plants?

The graph shows pressure changes during a cardiac cycle. Which row correctly identifies W, X, Y, and Z?

What is systolic blood pressure?

When they remain at high altitudes the red blood cell count of humans increases. Why does this occur?
1. to increase the Bohr effect
2. to increase the diffusion gradient for oxygen in the lungs
3. to maintain transport of oxygen

Which comparisons of blood, tissue fluid and lymph are correct?
1. Blood has a higher concentration of proteins than tissue fluid because the larger proteins are too big to pass through the endothelial pores into tissue fluid.
2. Lymph has a higher concentration of lymphocytes than tissue fluid as a high number of lymphocytes are located in lymph nodes.
3. Macrophages are too large to leave the blood to enter tissue fluid whereas neutrophils, which are much smaller, can enter tissue fluid and pass into lymph.

A number of different tissues occur in the walls of major blood vessels.
Which row correctly identifies the main tissues found in the three layers of the wall of an artery?

[Table]
outer layer (tunica externa)
middle layer (tunica media)
inner layer (tunica intima)
A. collagen, elastic, endothelium
B. collagen, muscle, elastic
C. elastic, collagen, endothelium
D. muscle, collagen, elastic

The photomicrograph shows a section through lung tissue.
Which structures are present in this photomicrograph?

[Table_1: Key - ✔ = present, ✗ = absent]

An athlete who smokes just before a race may not be able to run at their maximum speed because less oxygen is carried by the blood.
Which explanation is correct?

Some of the requirements of an efficient gas exchange system are a large surface area and a short diffusion distance. What is correct about how alveoli are adapted to meet these requirements? [Table_1]

The diagram shows three types of cell found in the human gas exchange system.
Apart from causing cancer, which cell types will be directly affected when a person is exposed to tar in cigarette smoke?

Some common antibiotics are listed. The action of each antibiotic is described.

1 rifampicin – inhibits RNA polymerase
2 streptomycin – inhibits 70S ribosomes
3 neomycin – inhibits DNA synthesis
4 ampicillin – inhibits peptidoglycan synthesis

Which of these antibiotics will affect the activities of bacterial cells only?

What could cause an outbreak of malaria in a country after it had been eliminated?
1 mosquitoes become resistant to insecticides
2 migration of population due to war
3 malarial parasites become resistant to quinine

Which disease is caused by a bacterium and can be spread by airborne droplets?

Smallpox has been eradicated, but malaria and cholera have not.
Which statements correctly explain this?
1. Cholera pathogens in the intestines are not destroyed by antibiotics.
2. Plasmodium antigens change during the life cycle.
3. Smallpox antigens remain stable.
4. Vaccines only work against viruses.

When a person is given a vaccination immunity to certain pathogens develops. Which of the effects of vaccination are correct?
1. production of antibodies to protect against future infections
2. results in artificial active immunity
3. stimulation of appropriate lymphocytes

What is the first response by the immune system to a pathogen?