1
1 mark
1 markWhich of the following is not a function of gibberellin in plants?
Apical dominance
Promotion of amylase activity
Increasing internodal length
Stimulating seed germination
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5.5 Plant & Animal Responses
21 mark
1 markWhich of the rows, A to D, correctly describes a plant response to a stimulus?
| Stimulus | Response | |
| A | Herbivory | Antifreeze chemicals produced in cells |
| B | Increased salinity | Plants produce tannins in their cells |
| C | Touch | Plants shut their stomata |
| D | Drought | Dropping leaves |
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31 mark
1 markWhich of the following is/are associated with injury to the hypothalamus?
| 1 | Inability to carry out thermoregulation |
| 2 | Loss of appetite |
| 3 | Slurred speech |
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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41 mark
1 markWhich of the following statements about reflex actions is correct?
The knee-jerk reflex is coordinated by the brain
They involve reflex neurones in the spinal cord
They increase survival chances
They do not contain synapses
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51 mark
1 markWhich of the following correctly describe(s) sarcomeres in skeletal muscle?
| 1 | Myosin binding sites are present |
| 2 | Z-lines mark the ends of each sarcomere |
| 3 | The A-band shortens when muscles contract |
1, 2 and 3
Only 1 and 2
Only 2
Only 2 and 3
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11 mark
1 markWhich of the following experiments would allow observation of a positive growth response to light?
| 1 | A mica barrier is inserted horizontally just below the shoot tips on the side of the shoot exposed to unidirectional light |
| 2 | A foil cap is placed over the shoot tip and the shoot is exposed to unidirectional light |
| 3 | A root tip is exposed to a unidirectional light source |
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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21 mark
1 markMaize 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?
Water loss by transpiration is the lowest in the day 0 group
The water potential of the guard cells is increased in the day 1 group
Surrounding temperatures increased in the day 3 and day 7 groups
Influx of Ca2+ into the cytoplasm of the guard cells is greatest in the day 0 group
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31 mark
1 markThe 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?
In test plant 1, auxin moves laterally across the tip of the shoot, away from the light
Auxin from the agar block in test plant 2 reduces pH levels in the cell walls, increasing the plasticity and flexibility of the stem
There is a reduced auxin concentration in test plant 1 after the stem is cut
Application of auxin to cut shoots makes it easier to propagate new plants
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41 mark
1 markTwo 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?
Gibberellins are produced during the early stages of seed germination
Plants without gibberellins have reduced stem elongation
Plants with gibberellin have a higher rate of amylase synthesis
In plants exposed to high wind damage, around 10% of surviving individuals were treated with gibberellin, while around 30% were not
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51 mark
1 markWhich of the following statements, A to D, correctly describes the effect of ethene on the ripening of mango fruits?
It stimulates the breakdown of cell walls in the outer layer of the abscission zone
It reduces auxin concentrations
It triggers an increased respiration rate in the cells
It delays the ripening of fruits
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11 mark
1 markThe 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?
meristem, shorten, destroyed, different
tip, elongate, destroyed, similar
meristem, shorten, synthesised, raised
tip, elongate, synthesised, similar
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21 mark
1 markA 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?
ABA causes fruit ripening.
ABA prevents leaf drop.
ABA causes phototropism.
ABA stimulates stomatal closing.
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31 mark
1 markWhich of the following statements, A to D, is evidence for geotropism?
Leaves are shed from deciduous plants in the autumn.
Roots grow downwards.
Shoots grow towards the light.
Flowers can change position throughout the day.
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41 mark
1 markMany 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?
- Auxin
- Ethene
- Giberellin
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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51 mark
1 markThe 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?
- Volicitin release reduces herbivory in N. rustica.
- Volicitin release increases M. sexta growth rate.
- Volicitin release reduces parasitism of M. sexta by C. congregata
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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61 mark
1 markThe 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?
W and X
W and Y
W and Z
Y and Z
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71 mark
1 markThe 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?
| Stimulus | Receptor | Effector | Response | |
| A | Loud sound | Hair cells in the inner ear | Muscles attached to the stapes bone | The stapes bone is pulled away from the cochlea |
| B | The stapes bone is pulled away from the cochlea | The ear | Muscles in the arm | An individual puts their hands over their ears |
| C | Loud sound | Hair cells in the inner ear | The stapes bone | The stapes bone moves away from the cochlea |
| D | Sound waves | The inner ear | The cochlea | The cochlea is not damaged |
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81 mark
1 markWhich of the following statements can be used to help explain an increase in heart rate?
- Impulses are sent along sympathetic neurones to the SAN.
- Acetylcholine is secreted at the synapse with the SAN.
- An increase in carbon dioxide concentration is detected by baroreceptors in the carotid arteries.
- There is a high frequency of nerve impulses from the receptors.
Only 1 and 2
Only 1, 3, and 4
Only 1 and 4
Only 2 and 4
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91 mark
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 A band gets shorter and the I bands stay the same length.
The A band gets shorter and the distance between the two Z lines decreases.
The A band gets shorter and the I bands get shorter.
The A band stays the same length and the I bands get shorter.
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101 mark
1 markThe 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?
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111 mark
1 markWhich statement relating to muscle contraction is correct?
Calcium ions are released from the sarcoplasmic reticulum and bind to tropomyosin.
Calcium ions are actively transported into the sarcoplasm.
Myosin heads function as ATPase enzymes, hydrolysing ATP.
Aerobic respiration provides ATP for muscle contraction during high intensity exercise.
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