AS & A Level Biology - 9700 Paper 1 2020 Winter Zone 1

Which row shows the correct order of size of these cell structures?

1. width of a mitochondrion
2. width of a ribosome
3. width of a cell surface membrane
4. width of a chloroplast

The diagram shows a stage micrometer scale viewed through an eyepiece containing a graticule.
The small divisions of the stage micrometer scale are 0.1 mm.

The stage micrometer scale is replaced by a slide of a plant cell.

What is the actual length of the nucleus in the plant cell?

Insulin is a hormone synthesised from two polypeptide chains inside cells of the pancreas.
Which row shows the cell structures that are used in producing insulin and releasing it from the cells?

[Table_1]

The electron micrograph shows a cell structure in a eukaryotic cell.
Which statements about this cell structure are correct?
1. ATP is synthesised in this cell structure.
2. The cell structure is made of protein molecules.
3. The cell structure replicates during interphase of the cell cycle.

Four students were asked to match the function with the appearance of some cell structures in an animal cell.
The functions were listed by number.
1. synthesis of polypeptides
2. synthesis of lipids
3. packaging of hydrolytic enzymes that will remain in the cell

The appearances were listed by letter.
V membranes which surround an enclosed inner cavity
W non-membrane-bound, spherical structures
X a double membrane interspersed with pores
Y non-membrane-bound, cylindrical structures
Z membrane-bound sacs, arranged as a flattened stack

Which student correctly matched the numbered function with the appearance of the cell structure?
[Table_1]

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

A student carried out the Benedict’s test on two different types of milk, X and Y.
A sample of each type of milk was heated to 100°C in a water-bath with Benedict’s solution and the time taken for the first appearance of a colour change was recorded.
The results are shown in the table.

[Table_1]

Which row shows the biological molecule the student detected in each sample of milk and the sample of milk with the highest concentration of this biological molecule?

The diagram shows the structure of a monomer. [Image_1: Monomer Structure]
Which molecules contain this monomer? [Image_2: Venn Diagram]

Which molecules are formed by condensation which involves a carboxyl group?

Which row correctly matches the function with the structural features of cellulose, collagen, glycogen or triglyceride? [Table_1]

The diagram shows the amino acids in a polypeptide.
An enzyme catalyses the hydrolysis of any peptide bond between a non-polar amino acid and any polar amino acid.
How many small peptides and single amino acids will be formed by the action of this enzyme?

Which properties of water reduce temperature changes inside cells?
1. cohesion
2. latent heat of vaporisation
3. specific heat capacity

Which enzyme is extracellular?

The graph shows how the concentration of components of an enzyme-catalysed reaction changes with time.
Which line represents enzymes with empty active sites?

Which effects can non-competitive inhibitors have on enzyme-controlled reactions?
1 lower the $K_m$ value
2 reduce the concentration of the product
3 reduce the rate of a metabolic pathway

Which processes can allow transport into or out of a cell?
1 active transport
2 facilitated diffusion
3 osmosis

Plant cells were put into one of three different concentrations of sugar solution, 10%, 5% and 2.5%. The cells were left for 50 minutes and then observed using a light microscope.

Which statements are correct?
1. Cell Y had a lower water potential than the sugar solution it was put into.
2. Cell Z was put into the 10% sugar solution.
3. Cell Z had a less negative water potential than the sugar solution it was put into.

During telophase of mitosis, a scientist stains the chromosomes of a diploid animal cell with a fluorescent dye to observe the telomeres.
This cell has 22 chromosomes.
How many telomeres will the scientist observe in one of the nuclei?

Methotrexate is a drug used to treat cancer. It can act as an enzyme inhibitor preventing the synthesis of nucleotides containing thymine.
Cells treated with methotrexate are not able to complete the cell cycle.
A cell entering telophase is treated with methotrexate.
Which stage of the cell cycle will be affected by the action of methotrexate?

Which stage of mitosis is correctly described?

The diagram represents a nucleotide containing cytosine.
Which statements about this nucleotide are correct?
1. The carbohydrate could be ribose.
2. The organic base contains nitrogen.
3. Base pairing occurs with guanine.
4. Cytosine is a purine.

A section of DNA contains 73 base pairs.

[Table_1]

Which row represents the correct number of bases?

The photograph shows a section of a stem. Which labelled part is the xylem?

Some fungi cause wilting in crop plants by growing within the xylem vessel elements. Which process will be directly affected by these fungi?

Which features have a role in the transport of water in xylem vessel elements?
1. capillary action
2. adhesion
3. hydrogen bonding

The loading of sucrose into companion cells involves a number of processes. Which process is active?

The statements describe events that occur during the movement of sucrose.
1. Hydrostatic pressure is decreased.
2. Hydrostatic pressure is increased.
3. Sucrose is loaded into the phloem vessel.
4. Sucrose is unloaded from the phloem vessel.
5. Water moves by osmosis into the phloem.
6. Water moves by osmosis out of the phloem.
7. Water potential decreases in the phloem.
8. Water potential increases in the phloem.
Which sequence correctly describes what happens in a plant at a source during the movement of sucrose?

Which are present in the walls of capillaries?
[Table_1]

The photomicrograph shows three white blood cells labelled X, Y and Z.
Which row correctly identifies these cells?

Which sequence of letters correctly identifies the order of events during the cardiac cycle?
T atrial walls contract
U impulse is delayed a fraction of a second
V wave of excitation enters the atrioventricular node
W wave of excitation passes down the Purkyne tissue
X wave of excitation spreads from the sinoatrial node
Y ventricles contract

The graph shows the effect of three different partial pressures of carbon dioxide on the oxygen dissociation curve for human haemoglobin.



What effect does decreasing the partial pressure of carbon dioxide have on haemoglobin?

What is correct about the transport of carbon dioxide by blood?
1. The enzyme carbonic anhydrase catalyses the formation of carbonic acid in red blood cells.
2. Carbon dioxide diffuses from active cells to red blood cells and reacts with water.
3. Carbonic acid dissociates forming hydrogen ions that combine with haemoglobin to form carbaminohaemoglobin.

Which statements about all bronchioles are correct?
1. they have goblet cells
2. they have ciliated cells
3. they have muscle tissue

The graph shows the volume of air breathed out quickly and with force, following a deep breath in, for three different people, X, Y and Z.
What is a possible explanation for the differences in the volume of air breathed out by these people shown?

The diagrams show some of the pathogens that cause disease in humans and some of the ways they are transmitted.
What is the correct pathogen and method of transmission for the disease TB?

The proportion of the local population who have malaria in area R is higher than the proportion in area S. Which factor causes this difference?

Species X is a single-celled eukaryote.

Species X has been genetically modified to produce penicillin, which does not harm the cell walls of species X.

What may be concluded from this information?

1 The cell walls of species X are chemically different from those of bacteria.
2 The cell walls of species X are made of peptidoglycan.
3 The cell walls of species X are made of cellulose.

When exposed to an antigen for a second time, memory cells stimulate a secondary immune response. Which correctly shows the secondary immune response?

Monoclonal antibodies are produced for use in diagnosis or treatment of disease. To obtain the antibodies for an antigen, a mouse is injected with the antigen.
Some of the events in the production of the monoclonal antibody are listed.

1. Plasma cells are fused with cancer cells to form a hybridoma.
2. Hybridomas that secrete the required antibody are identified and cloned.
3. B-lymphocytes that recognise the antigen multiply and become plasma cells.
4. Hybridomas divide by mitosis and secrete antibodies.
5. Plasma cells are removed from the mouse spleen.

What is the sequence of the first four events in the production of the monoclonal antibody?

Which row describes passive immunity? [Table_1]