AS & A Level Biology - 9700 Paper 1 2013 Winter Zone 3

For which process is the large surface area of the cristae in the mitochondria important?

What is not a limitation of an electron microscope?

What explains why cells with no nucleoli die?

Which statements about a typical prokaryotic cell are correct?
1. It is smaller than 2 \mu m.
2. It has a nucleus.
3. It has circular DNA.
4. It has small (70S) ribosomes.

When mitochondria are extracted from cells for biochemical study, they are usually kept in a 0.25 mol dm^-3 sucrose solution. Why is the sucrose solution used?

Which shows the basic unit of cellulose?

Which explains why haemoglobin is suitable as an oxygen carrier?
1. The haem group combines with oxygen.
2. The iron combines with oxygen reversibly.
3. Haemoglobin changes shape as oxygen loads.

Which diagram shows part of a structural polysaccharide?

The diagrams show the structures of two amino acids, each of which has more than one amine (–NH₂) group.
A peptide bond is formed between the two amino acids. Which groups form the peptide bond?

Which combination of bond types correctly shows the weak and strong bonds that hold a molecule of protein in shape? [Table_1]

Which is correct for competitive inhibitors of enzymes?
1. They occupy the active site of an enzyme.
2. They have exactly the same shape as the substrate.
3. They can be used to control the rate of enzyme activity.
4. They can bind to a site on an enzyme other than the active site.

The graph shows the course of an enzyme-catalysed reaction at 30°C.
What is true at time X?

Which statement concerning the role of cholesterol in the cell surface membrane is correct?

Which processes that contribute to transport across cell surface membranes are active or passive? [Table_1]

In an investigation, four sucrose solutions were separated from each other by partially permeable membranes.

solution 1: 1.1 mol dm^-3
solution 2: 0.8 mol dm^-3
solution 3: 0.5 mol dm^-3
solution 4: 0.1 mol dm^-3

Which shows the direction in which water will move between the solutions?

The diagram shows a partially plasmolysed plant cell.

What is found at Z?

The diagram shows part of the life cycle of the honey bee, Apis mellifera.

Where does mitosis occur?

The graph shows the change in the quantity of DNA in a cell during a reduction division (meiosis).

![Image 1]

A cell with one pair of chromosomes (2n = 2) undergoes meiosis.

Which nucleus is formed as a result of this division?

What is the minimum number of hydrogen bonds in a length of DNA containing 700 base pairs?

Which term best describes the length of DNA that codes for the synthesis of a polypeptide?

Which statements about complementary base pairing are correct?
1. It occurs during translation.
2. Purines and pyrimidines are the same size.
3. The base pairs are of equal length.
4. Uracil forms three hydrogen bonds with adenine.

What is transpiration and which advantage does it give to a plant? [Table_1]

Which feature of xylem vessel elements allows them to stay open as transpiration increases?

What occurs in the sieve tube elements of a photosynthesising leaf and an actively growing root?
[Table_1]

What occurs in the apoplast and symplast pathways? [Table_1]

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

Which statement correctly identifies a similarity between blood plasma and tissue fluid?

Which reactions are not likely to occur in blood that is passing through active tissues?
1. $\text{Hb} + 4\text{O}_2 \rightarrow \text{HbO}_8$
2. $\text{HbO}_8 + \text{H}^+ \rightarrow \text{HHb} + 4\text{O}_2$
3. $\text{HCO}_3^- + \text{H}^+ \rightarrow \text{H}_2\text{CO}_3$
4. $\text{H}_2\text{O} + \text{CO}_2 \rightarrow \text{H}_2\text{CO}_3$

The pressure of blood entering capillaries is about seven times higher than that of blood leaving the capillaries. What correctly explains this observation?
1. Blood pressure decreases with distance from the heart.
2. Tissue fluid formation is due to a net loss of plasma from capillaries.
3. Veins have fewer elastic and muscle fibres in their walls than arteries.

The red blood cell count of humans increases when they remain at high altitudes.
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

Goblet cells are found in the trachea. Which organelles would be found in large numbers in a goblet cell?
[Table_1]

The photomicrographs show a TS of an artery from a non-smoker and a TS of an artery from a smoker. What is the reason for the appearance of smoker's artery?

Which row describes emphysema? [Table_1]

Which row is correct? [Table_1]

Scientists are concerned that avian (bird) flu caused by the H5N1 virus could infect humans and cause a pandemic.
What could help prevent humans from spreading the disease?
1. killing all poultry
2. reducing the number of air flights
3. taking a course of antibiotics

What are the function(s) of plasma cells during an immune response?
1 destroy cancer cells
2 differentiate into memory cells
3 secrete antibodies

Some of the facts about a pathogen, P, are that:
1. it is transmitted in food and water
2. it lives in human intestines
3. it has many genes coding for surface proteins
4. it changes its surface antigens
5. it may or may not trigger an immune response.

Which explains why it is difficult to develop an effective vaccine for P?

Which description is correct for B-lymphocytes? [Table_1]

In a mangrove ecosystem, leaves from the grey mangrove plants fall into the water and sink to the mud below. They are then broken down by bacteria and fungi.
Invertebrates such as crabs, prawns, and molluscs live in the mud and feed on the dead leaves. The bullseye fish feeds on the invertebrates. Humans eat prawns, crabs and fish.
Herons and other wading birds live and breed in the mangroves. These birds feed on invertebrates and fish.
What is correct about this ecosystem?

Two species of birds feed on different insects living on the same tree and so do not compete for food. Which statement describes these two species of birds?