AS & A Level Biology - 9700 Paper 1 2023 Summer Zone 3

Which feature is visible with a light microscope using a natural light source?

The electron micrograph shows a structure found in the cytoplasm of an animal cell.

Which biological molecules are found in this structure?
1 nucleic acids
2 proteins
3 phospholipids

Which cell structures contain nucleic acid?
1. cytoplasm
2. lysosomes
3. mitochondria

Mitochondria are thought to have evolved from prokaryotic cells that were ingested by an ancestral cell.
Which feature have prokaryotes lost during their evolution into mitochondria?

Which polymers are present in all viruses, all prokaryotes and all eukaryotes?
1. polynucleotides
2. polypeptides
3. polysaccharides

How many of the listed structures typically contain genetic material that has telomeres?
• bacterial cell
• chloroplast
• mitochondrion
• nucleus

Steps 1, 2, 3 and 4 are used to test for a non-reducing sugar.
1. Put 5 cm³ of solution into a test-tube.
2. Add a few drops of acid.
3. Neutralise with alkali.
4. Add 6 cm³ of Benedict’s solution.
When is the solution heated or boiled?

Which features contribute to the function of a cellulose molecule?
1. Long chains of glucose molecules coil into a helix.
2. Many hydrogen bonds form between adjacent chains.
3. It is insoluble in water.

What correctly describes triglycerides?

Cocoa butter contains three different triglycerides. These triglycerides are made from the fatty acids:

• oleic acid (O)
• palmitic acid (P)
• stearic acid (S)

Which molecules contain at least four double bonds?

The diagram shows the amino acid glutamic acid.

What is the R group for glutamic acid?

The diagram shows three interactions that hold protein molecules in shape.

Which row identifies these interactions?

Some animals produce antimicrobial proteins which protect them from pathogens. These proteins could be used to kill human pathogens, however when used as a medicine they are broken down by protein-digesting enzymes.
Replacing one of the amino acids found in the protein with an amino acid that had been synthesised in the laboratory resulted in a modified protein that was not broken down.
What could explain why this modified protein was not broken down by the protein-digesting enzymes?
1. The modified protein has a different tertiary structure to the original protein.
2. The modified protein is not complementary in shape to the enzyme’s active site.
3. The modified protein is unable to induce a fit with the protein-digesting enzyme.

A student investigated the effect of substrate concentration on the rate of an enzyme-catalysed reaction. A graph was plotted to show the relationship between these two variables. The student was asked to take readings from the graph that could be used to determine the Michaelis–Menten constant, $K_{m}$, for this enzyme.
J, K, L, and M show points read from the graphs which the student could use to determine the value of $K_{m}$.

Which two readings must the student use to determine the value of $K_{m}$?

The end-product of a metabolic pathway can act as a competitive inhibitor. This is called end-product inhibition and allows a cell to control a metabolic pathway.
The diagram shows a metabolic pathway where the end-product could act as an inhibitor of enzyme W.

What would be the effect if enzyme Z was inhibited by the end-product instead of enzyme W?

Which row shows the distribution of cholesterol and the carbohydrate chains of glycolipids and glycoproteins in a cell surface membrane? [Table_1]

Which row correctly describes all the possible relative concentrations of a substance when the substance is moved by endocytosis or exocytosis? [Table_1]

Which statement about simple diffusion is correct?

Plant cells with the same water potential in their cytoplasm were each 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.

Which row describes some properties of stem cells? [Table_1]

The mitotic index is a measure of the proportion of cells that are undergoing mitosis in an area of tissue. It is calculated using the formula shown.
mitotic index = (number of cells undergoing mitosis ÷ total number of cells) × 100
A scientist calculated the mitotic index of areas of onion root at different distances from the tip of the root. The results are shown.

Which statement is correct?

Which molecules make up the structure of ATP?
1. adenine
2. thymine
3. deoxyribose
4. phosphate
5. ribose

A short piece of DNA, 19 base pairs long, was analysed to find the number of nucleotide bases in each of the polynucleotide strands. Some of the results are shown.
[Table showing number of nucleotide bases]
How many cytosines were in strand 1?

Which statement about the role of DNA polymerase in the process of semi-conservative replication of DNA is correct?

The diagram shows the process of translation occurring at a ribosome.
What is the base sequence at S?

Which row correctly explains how the structures of phloem sieve tube elements and xylem vessel elements are related to their functions as transport systems? [Table_1]

Which component of plants is used by the apoplast pathway as water is moved from the soil to the xylem?

Which statements correctly describe transport pathways in dicotyledonous plants?
1. In the symplast pathway, water may move through intercellular spaces.
2. The symplast pathway may be blocked by the tonoplast.
3. In the apoplast pathway, water does not move through plasmodesmata.
4. The apoplast pathway may be blocked by the Casparian strip.

Plants, such as the tobacco plant, retain very little of the water they take in and the volume of water lost during transpiration is very high. This is because these plants can only absorb carbon dioxide through open stomata.

Plants use carbon dioxide to synthesise glucose molecules. It is estimated that 400 molecules of water are lost for each carbon dioxide molecule gained.

How many water molecules are lost for a plant to synthesise one molecule of glucose?

Which changes occur as sucrose is transferred from leaves into phloem sieve tubes to be transported to a sink?
[Table_1: water potential in phloem sieve tubes and volume of liquid in phloem sieve tubes]

The graph shown does not have any axis labels.


Which row shows appropriate labels for the axes that would explain mass flow in phloem?

What is present in the blood in human veins?
1. chloride ions
2. carbonic anhydrase
3. oxyhaemoglobin

The photomicrograph shows two blood vessels P and Q. Both these blood vessels are part of a network which transports blood around the body. Which row is correct for blood vessel P and blood vessel Q?

The diagram shows a blood capillary and the tissue fluid which surrounds it.

[Image_1: Diagram showing tissue fluid, blood capillary with points W, X, Y, and Z]

Tissue fluid is formed when fluid and solutes from blood plasma pass through tiny gaps in the capillary wall. Most tissue fluid is then returned to the blood in the capillary.

Which pressures will be needed at points W, X, Y and Z so that this system can function?

[Table_1: Pressure values at W, X, Y, and Z]

What happens during ventricular systole in a mammalian heart?

The photomicrograph shows a part of the human gas exchange system with one tissue labelled P. Which row is correct?
[Table_1]

How many times must a molecule of oxygen pass through a cell surface membrane as it diffuses from the airspace inside an alveolus, through a cell in the capillary wall, to bind to a molecule of haemoglobin?

A student wrote four statements about cholera. Which statement is not correct?

Monoclonal antibodies are produced using the hybridoma method. What are removed from the spleen of a mouse to produce monoclonal antibodies?