AS & A Level Biology - 9700 Paper 1 2024 Winter Zone 1

The diagram shows a transverse section through a blood capillary.

What is the magnification of the drawing?

Which statement explains why lymphocytes with no nucleoli die?

Density gradient centrifugation is used to separate cell structures by their relative density. Larger cell structures have greater density and sink further down the centrifuge tube. What is the correct order of the cell structures, starting from the top of the centrifuge tube?

Which cell structures contain nucleic acids?
1. chloroplasts
2. Golgi bodies
3. lysosomes
4. ribosomes

The statements describe processes that take place in a secretory cell.

1. Modification of the protein occurs in the Golgi body.
2. mRNA leaves the nucleus.
3. Ribosomes bind to mRNA during translation.
4. Transcription of a specific DNA sequence occurs.
5. Vesicles fuse with the cell surface membrane.
6. Vesicles transport the protein to the Golgi body.

Statement 4 is the first process, and statement 5 is the last process.
What is the correct sequence of the middle four processes?

How many types of structures with a double membrane that are found in animal cells are also found in plant cells?

A naturally occurring polysaccharide synthesised in a plant is a branched chain of $\alpha$-glucose.
The straight parts of the molecule are linked by $\alpha$-1,6 glycosidic bonds with only a small number of branches which are linked by either an $\alpha$-1,3 glycosidic bond or an $\alpha$-1,4 glycosidic bond.
Which polysaccharide has a structure most similar to that described?

The diagram shows a triglyceride.

An enzyme was used to digest this triglyceride into glycerol and fatty acids.
Which scatter plot correctly represents each fatty acid component of the triglyceride?

The diagram shows how the alternating nature of \( \beta \)-glucose monomers along a chain allows hydrogen bonds to form between consecutive monomers.



Hydrogen bonds in cellulose affect the tensile strength (the ability to withstand pulling forces without breaking).

How do the hydrogen bonds shown in the diagram help cellulose function as a suitable material for a cell wall?

Two solutions, 1 and 2, each contained a mix of two different biological molecules. One solution contained starch and sucrose, and the other contained glucose and protein.
The two solutions were tested with a variety of reagents to identify the presence of the biological molecules in the solution.
The table shows the results recorded for the various tests.
Which row identifies the two solutions?

[Table_1]

The diagrams show parts of three pairs of amino acids within a protein. The pairs are labelled X, Y and Z. Which row shows the correct type of interaction that would occur between the two amino acids in each pair? [Table_1]

A student carried out investigations at pH 1–8 to look at the effect of pH on an enzyme-catalysed reaction.
The optimum condition for this enzyme is the acidic environment of the stomach at pH 1–2.
The remaining substrate concentration was measured after five minutes at each different pH.
Which graph shows the effect of increasing pH on substrate concentration remaining after five minutes?

Which statement is correct for a non-competitive inhibitor?

Pyrophosphatase enzymes catalyse a hydrolysis reaction.

In experiment 1, a scientist studied the rate of this reaction, using a colorimeter.
The absorbance of the solution was measured at regular intervals until all of the pyrophosphate ions had been converted into phosphate ions.
In experiment 2, the scientist repeated the procedure with a higher concentration of pyrophosphatase. All other variables were standardised.
Which graph shows the effect of increasing the concentration of pyrophosphatase?

Proteases are a group of enzymes that digest proteins. Which statements about proteases are correct?
1. A bacterial protease that is secreted from a disease-causing bacterium could act as an antibody and cause the production of antigens against it.
2. Non-competitive inhibition of a protease that has an optimum condition of pH 2 can be overcome by increasing the substrate concentration and increasing the pH.
3. Water molecules are required when peptide bonds that link the monomers together are broken by the action of proteases in hydrolysis reactions.

The diagram shows part of a cell surface membrane.
Which row correctly identifies the molecules labelled 1 and 2?

The diagram shows the mean dimensions of an epithelial cell in micrometres (\mu m). Which row shows the surface area to volume ratio of the epithelial cell and how the surface area to volume ratio of the cell would change if the cell width doubled? [Table_1]

Which diagram shows the correct direction of net water movement between the four cells due to osmosis?
[Image_1: Diagram showing four cells with water potentials]
Key: \( \Psi = \text{water potential} \)

An investigation was carried out into the effect of four different treatments on the permeability of the cell surface membranes and tonoplasts of beetroot cells. Beetroot cell vacuoles contain a red pigment. This pigment cannot diffuse through the tonoplasts or cell surface membranes.
1 cm³ cubes were cut from beetroot tissue and washed in running water for 20 minutes to remove any pigment released from damaged cells.
Two cubes were then placed in each of the four test-tubes containing different contents and observed for five minutes.
Which row shows a correct explanation for the observation recorded for one of the treatments?
[Table_1]

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

What are the correct roles of mitosis?
[Table_1]

Which row about the stages of the mitotic cell cycle is correct?
[Table_1]

Which statements describe how a gene mutation can lead to the production of a non-functional protein?
1. During transcription, an incorrect nucleotide is added to a DNA molecule.
2. The mutated gene results in a new codon being transcribed.
3. The order of the bases in an anticodon on tRNA is altered during translation.

There are 64 chromosomes in the muscle cells of a particular mammal.
How many DNA molecules are present in a cell during early prophase and telophase of mitosis?
[Table_1]

The diagram shows the nucleotide sequence of a small section of the transcribed strand of a gene.

GCG CGC GGC GCG

The table shows the amino acids coded for by 10 mRNA codons.

[Table_1]

What is the sequence of the four amino acids in the polypeptide translated from this small section of a gene?

How many hydrogen bonds form when adenine and cytosine each bind to their complementary bases?
[Table_1]

Which statement correctly identifies the movement of sucrose and amino acids in plant vascular tissue?

Xylem vessel elements are specialised cells that are adapted for the transport of water.
Which statement correctly matches an adaptation of a xylem vessel element to its function?

A student makes an accurate labelled plan diagram of a section of a leaf containing a vascular bundle.
Which statement correctly describes part of their plan diagram?

Some babies are born with a hole between the right and left atria. These babies are found to have an increased number of red blood cells.
What is the reason for this increase in red blood cells in these babies?

An increase in carbon dioxide in human blood shifts the oxyhaemoglobin dissociation curve to the right.
What is the explanation for this effect?

`Heart block` is a disease which can result in a lower than normal heart rate. A doctor treating a person with heart block found that electrical impulses were initiated as normal but were not correctly conducted to the ventricles, so the rate of ventricular contraction was slowed.
Which parts may not be functioning correctly in the person with heart block?
1 atrioventricular node (AVN)
2 Purkyne tissue
3 sinoatrial node (SAN)

The pumping action of the heart creates hydrostatic pressure in the blood. The table shows the hydrostatic pressure in a blood capillary.

[Table_1]

About 90% of the tissue fluid which surrounds a capillary is returned to the blood at the venule end.

How is this achieved?

What is the function of cilia in the gas exchange system?

Which tissues are present in the walls of a trachea and an alveolus?
[Table_1: tissue table with epithelium with goblet cells and smooth muscle presence indicators]

The photomicrograph shows part of a bronchus. Which label identifies cartilage?

Which structures or compounds are present in a typical cell that can be killed by penicillin?
1. circular DNA
2. cytoplasmic DNA
3. 70S ribosomes
4. peptidoglycan

Three statements about cholera and its transmission are listed.
1 The pathogen causes watery faeces.
2 Frequent air flight has led to mobile populations.
3 The pathogen is transmitted through water.
Which statements are reasons why outbreaks of cholera are likely to occur?

What will be produced by the division of memory cells during a secondary immune response?

A vaccine is used to give immunity to the virus that causes the disease influenza.
A new influenza vaccine is needed every year because the virus mutates regularly.
What is the reason for needing a new influenza vaccine every year?