AS & A Level Biology - 9700 Paper 1 2024 Summer Zone 2

A prokaryotic cell which is 1\(\mu m\) in diameter is magnified 50 000 times in an electron micrograph.
What is the diameter of the cell in the electron micrograph?

The diagram shows a plant cell with some labelled structures.

Which labelled structures are bound by a double membrane?

Which size of ribosome is found in mitochondria and typical prokaryotic cells?

Which row about typical prokaryotic cells and typical animal cells is correct?
[Table: Lysosomes present for the breakdown of old organelles / ATP is produced by the cell]
Key:
✓ = correct for typical prokaryotic cells and typical animal cells
✗ = not correct for both cells but correct for either typical prokaryotic cells or typical animal cells

Which row is correct for the structures present in typical plant cells and typical animal cells?
[Table_1]

Which row is correct for cellulose?
[Table_1: rotation of alternate monomers by 180°
shape of molecule
hydrogen bonds between molecules]

Which statements about peptide bond formation are correct?
1. The bond formation occurs between a carbon of one amino acid and a nitrogen of the next amino acid after the amino acids detach from tRNA.
2. The bond formation occurs at the ribosome while the amino acids are still attached to tRNA, and is a hydrolysis reaction.
3. The bond formation is important for growth of an organism and when the bond forms, a water molecule is removed.

The diagram shows naturally occurring D-glucose and a form of glucose that can be synthesised in the laboratory, known as L-glucose.



The enzyme glucose oxidase catalyses the oxidation of D-glucose. The enzyme cannot catalyse the oxidation of L-glucose.

Which statement about L-glucose explains this?

Tests for biological molecules were carried out on three solutions. Each solution contained only one type of biological molecule.

The observations were as follows.

[Table_1]

Which solutions would contain either sucrose or amylase?

Which row describes the expected effect on $V_{max}$ and $K_m$ when a competitive reversible inhibitor is added to an enzyme-catalysed reaction?
[Table_1]

The graph shows the effect of substrate concentration on the rates of reaction of three enzymes, X, Y, and Z.

What is the correct order of affinity of these enzymes for their substrates, starting with the enzyme with the highest affinity?

Which row correctly identifies the weak and strong bonds in the tertiary and quaternary structure of a typical protein?
[Table_1]

Which row correctly describes haemoglobin? [Table_1]

Which process always takes place without the involvement of energy from ATP?

The diagram shows the entry of molecule X into a cell.
Which row shows a property of molecule X and the effect of the concentration of ATP in the cytoplasm on the rate of entry of molecule X?
[Table_1]

The electron micrograph shows some human blood cells.

Which row correctly shows the net movement of water by osmosis and the water potential of the cytoplasm of cell X compared with the solution surrounding the cells?
[Table_1]

A red indicator solution was mixed with agar and the resulting solid was cut into small cylindrical blocks. The blocks were placed in an acid which turns the indicator yellow and all other variables were kept constant. The dimensions of the blocks are shown.

block 1 height 3 mm diameter 6 mm
block 2 height 6 mm diameter 12 mm
block 3 height 8 mm diameter 16 mm

The formula for calculating the surface area of a cylinder is $2\pi rh + 2\pi r^2$. The formula for calculating the volume of a cylinder is $\pi r^2 h$.

Which row shows the correct surface area (SA) to volume (V) ratio for each block and the time taken for the block to turn yellow?
[Table_1]

Which metabolic processes will be very active in a cell that has just completed cytokinesis?
1. ATP formation
2. DNA replication
3. protein synthesis

The diagram shows a typical mitotic cell cycle and the point in the cell cycle that has been reached by each of four cells, V, W, X and Y.

Which row correctly identifies the cells that match the two descriptions?
[Table_1: DNA replication is complete but the cell has not yet reached its maximum size, preparation for microtubule formation is nearly complete but chromosomes have not yet condensed]

The graph shows the mean length of the spindle fibres during mitosis. Which region of the graph shows when all the centromeres have detached from the spindle fibres?

The mRNA codons ACU, ACC, ACA and ACG all code for the same amino acid, threonine.
Which anticodons could specify an amino acid other than threonine?
1 UCA
2 ACC
3 UGU
4 UGC

Which bond formation does DNA polymerase catalyse?

In eukaryotes, the RNA molecules formed during transcription are modified by the removal of non-coding sequences. This is followed by the joining together of coding sequences to form mRNA.
What are the coding sequences also called?

Which row correctly identifies sinks for sucrose transported by mass flow in plants? [Table_1]

The diagram shows a transverse section through a transport tissue in a plant.

Which row correctly identifies cell 1 and cell 2?

Which statement correctly describes the movement of solutes in the symplast pathway?

Which statement helps to explain why water molecules are forced to move through xylem vessel elements as a consequence of transpiration?

The diagram shows the internal structure of the mammalian heart. Which letter identifies the location of the atrioventricular node?

The diagram shows pressure changes in the left side of the heart during the cardiac cycle.
What happens in the heart at X?

Which components of blood are present in tissue fluid?
[Table_1]

In the lungs, movement of dissolved carbon dioxide out of the capillaries occurs in one of two ways:
• by diffusion through the endothelial cells of the capillaries
• by leakage through pores in the endothelial cells of the capillaries.

What is the minimum number of times that a carbon dioxide molecule that has been transported to the lungs in a red blood cell must cross a cell surface membrane to reach an air space in an alveolus?

What maintains the steep concentration gradients needed for successful gas exchange in the lungs?
1. Air flow in the alveoli is in the opposite direction to blood flow in the capillaries.
2. Blood arrives in the lungs with a lower oxygen concentration and a higher carbon dioxide concentration than the air in the alveoli.
3. Blood is constantly flowing through and out of the lungs, bringing a fresh supply of red blood cells.

Where is cartilage tissue always found in the human gas exchange system?

Scientists compared the density of goblet cells in the lungs and the density of mucus in the lungs of three groups of people:
• people who do not smoke and do not have lung disease
• people who smoke tobacco but do not have lung disease
• people who smoke tobacco and have lung disease.

The results are shown in the table.

[Table_1]

What is indicated by these data?
1 There is a positive correlation (relationship) between density of goblet cells and density of mucus.
2 Lung disease results in an increase in goblet cell density.
3 There is an association between tobacco smoking and an increase in mucus density.

Which disease does \textit{Mycobacterium bovis} cause?

An antibiotic inhibits the formation of cross-links between the molecules that form cell walls in bacteria.
Which statements explain why bacteria are killed by the antibiotic?
1. The bacterial cell is destroyed by osmotic lysis.
2. Cellulose molecules cannot form hydrogen bonds.
3. The cell wall is no longer partially permeable.

Scientists investigated the effect of increasing concentrations of an antibiotic on the development of antibiotic resistance in bacteria.
The scientists grew four groups of bacteria and added a different concentration of antibiotic to each group. The number of resistant bacteria and the total population of bacteria were measured at intervals for 24 hours for each group.
The graphs show the results.

Which statements are correct conclusions that can be made from the results of this investigation?
1. Increasing the concentration of antibiotic decreases the population of non-resistant bacteria at the end of 24 hours.
2. The proportion of antibiotic-resistant bacteria increases with increasing concentrations of antibiotics.
3. Increasing the concentration of antibiotic always increases the number of resistant bacteria.

What is the correct sequence of events in a primary immune response?

Which statement about the properties of the antigen-binding sites in different antibody molecules is correct?

The diagram shows a stage in monoclonal antibody production.

What is represented by X?