Plant & Animal Responses (OCR A Level Biology)

The following passage outlines the process of phototropism in plants:

Auxin is synthesised in cells at the ....................... of the shoot. Auxin causes the cells to ....................... on one side, so the stem bends.

Scientists originally thought auxin was ....................... by light but this was disproved by the fact that plants growing in the dark and plants growing in unilateral light had ....................... auxin levels.

Which option, A to D, is the correct sequence of missing words?

A scientist tested a plant suffering from water stress. The plant was found to have high levels of abscisic acid (ABA) in its tissues.

Which of the following statements, A to D, explains this observation?

Which of the following statements, A to D, is evidence for geotropism?

Many trees drop their leaves in the autumn.

Which of the following plant hormones is/are thought to be involved in the control of leaf drop?

1. Auxin
2. Ethene
3. Gibberellin

The commercially grown tobacco plant, Nicotiana rustica, has many pests. One such insect pest is Manduca sexta, which causes damage to the stems and leaves of N. rustica.

The tiny wasp Cotesia congregata lays its eggs inside the body of M. sexta. When the larvae develop they feed on the body of the host, eventually killing it.

N. rustica produces a volatile organic compound called volicitin when its leaves are damaged.

Volicitin attracts C. congregata at high concentrations.

Which of the following explains why N. rustica releases volicitin?

1. Volicitin release reduces herbivory in N. rustica.
2. Volicitin release increases M. sexta growth rate.
3. Volicitin release reduces parasitism of M. sexta by C. congregata

The image below is a diagram of the human brain.

Which of the labelled regions would be directly involved in learning to play a musical instrument?

The acoustic reflex is thought to provide protection for the delicate parts of the inner ear. 

The image below shows the structures inside the ear that are affected by the acoustic reflex.

In the acoustic reflex the stapes bone moves away from the cochlea, reducing the force of sound wave vibrations that are transmitted. The cochlea is a hollow, spiral shaped chamber that contains fluid and tiny hairs that move in response to sound wave vibrations.

Which of the rows in the table correctly identifies the pathway of the acoustic reflex?

Which of the following statements can be used to help explain an increase in heart rate?

1. Impulses are sent along sympathetic neurones to the SAN.
2. Acetylcholine is secreted at the synapse with the SAN.
3. An increase in carbon dioxide concentration is detected by baroreceptors in the carotid arteries.
4. There is a high frequency of nerve impulses from the receptors.

The diagram below shows a sarcomere within a muscle fibre.

Which of the following statements correctly describes the events observed during a muscle contraction?

The image below contains a transverse section through a muscle fibre (top) and an electron micrograph of skeletal muscle (bottom).

Which label, from A-D on the electron micrograph, correctly represents the transverse section of muscle fibre shown?

Which statement relating to muscle contraction is correct?

Which of the following experiments would allow observation of a positive growth response to light?

Maize leaves were treated with a solution of 12 % polyethylene glycol (PEG) for a period of 0, 1, 3 and 7 days. PEG can induce water stress in plants. 

The graph below shows the ABA content of the leaves of the four groups of maize plants.

Which of the following, A to D, is likely to be correct for the plants represented in the graph?

The diagram below shows the observations made when two plants are tested for the effect of auxin on growth.

Which of the following statements, A to D, correctly explains the observations above?

Two groups of trees were exposed to either low or high levels of wind damage. The graph below shows the percentage of surviving trees that were treated with gibberellin and that received no treatment.

Which of the following, A to D, correctly explains the data?

Which of the following statements, A to D, correctly describes the effect of ethene on the ripening of mango fruits?