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A Level Biology: Control and coordination MCQs — Biology

26 multiple-choice questions on A Level Biology: Control and coordination from Biology, each with the correct answer and, where available, a teacher's explanation. Read through them to revise the chapter, then practise the same questions one by one to test yourself.

1. Depolarisation during an action potential is caused by

  1. K⁺ ions diffusing out
  2. the Na⁺/K⁺ pump
  3. Ca²⁺ ions leaving
  4. Na⁺ ions diffusing into the axon through voltage-gated channels

Answer: D) Na⁺ ions diffusing into the axon through voltage-gated channels

Explanation: Na⁺ influx depolarises. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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2. ATP is needed in muscle contraction to

  1. open T-tubules
  2. release ACh
  3. detach the myosin head from actin and re-cock it
  4. bind Ca²⁺ to troponin

Answer: C) detach the myosin head from actin and re-cock it

Explanation: ATP breaks cross-bridges. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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3. Repolarisation is caused by

  1. K⁺ ions diffusing out through voltage-gated channels
  2. Ca²⁺ entering
  3. acetylcholine binding
  4. Na⁺ ions diffusing in

Answer: A) K⁺ ions diffusing out through voltage-gated channels

Explanation: K⁺ efflux. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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4. Glucose produced in the endosperm of barley is used by the embryo for

  1. photosynthesis
  2. closing stomata
  3. respiration and growth
  4. making gibberellin only

Answer: C) respiration and growth

Explanation: Energy for germination. AS & A Level Biology · Topic 15 Control and Coordination · 15.2 Control and coordination in plants

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5. The resting potential of a neurone is about

  1. +40 mV
  2. −70 mV
  3. 0 mV
  4. −120 mV

Answer: B) −70 mV

Explanation: Inside is negative at rest. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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6. During muscle contraction, Ca²⁺ ions bind to

  1. troponin
  2. tropomyosin directly
  3. actin
  4. myosin

Answer: A) troponin

Explanation: Troponin changes shape. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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7. Tropomyosin at rest

  1. forms the Z line
  2. hydrolyses ATP
  3. covers the myosin-binding sites on actin
  4. binds Ca²⁺

Answer: C) covers the myosin-binding sites on actin

Explanation: It blocks cross-bridge formation. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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8. The sodium–potassium pump moves

  1. 2 Na⁺ out and 3 K⁺ in
  2. 3 K⁺ out and 2 Na⁺ in
  3. 3 Na⁺ out and 2 K⁺ in
  4. Na⁺ in only

Answer: C) 3 Na⁺ out and 2 K⁺ in

Explanation: It uses ATP to maintain gradients. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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9. Ca²⁺ ions for muscle contraction are released from the

  1. mitochondria
  2. sarcoplasmic reticulum
  3. nucleus
  4. T-tubules

Answer: B) sarcoplasmic reticulum

Explanation: The SR stores Ca²⁺. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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10. Expansins are proteins that

  1. loosen links between cellulose microfibrils at low pH
  2. make auxin
  3. digest starch
  4. pump protons

Answer: A) loosen links between cellulose microfibrils at low pH

Explanation: They allow wall stretching. AS & A Level Biology · Topic 15 Control and Coordination · 15.2 Control and coordination in plants

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11. Gibberellin in barley seeds is released by the

  1. aleurone layer
  2. embryo
  3. endosperm
  4. testa

Answer: B) embryo

Explanation: The embryo produces gibberellin. AS & A Level Biology · Topic 15 Control and Coordination · 15.2 Control and coordination in plants

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12. The refractory period ensures that

  1. neurotransmitters are recycled
  2. impulses travel faster
  3. the resting potential is lost
  4. impulses travel in one direction and are separate

Answer: D) impulses travel in one direction and are separate

Explanation: Channels cannot reopen immediately. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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13. At a cholinergic synapse, the arrival of an action potential causes

  1. ACh to be hydrolysed
  2. K⁺ to enter the postsynaptic cell
  3. Ca²⁺ ions to enter the presynaptic knob
  4. vesicles to be made

Answer: C) Ca²⁺ ions to enter the presynaptic knob

Explanation: Ca²⁺ triggers exocytosis. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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14. T-tubules

  1. store ATP
  2. release acetylcholine
  3. connect sarcomeres
  4. carry depolarisation deep into the muscle fibre

Answer: D) carry depolarisation deep into the muscle fibre

Explanation: Infoldings of the sarcolemma. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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15. Acetylcholinesterase

  1. forms the myelin sheath
  2. opens calcium channels
  3. synthesises acetylcholine
  4. hydrolyses acetylcholine in the synaptic cleft

Answer: D) hydrolyses acetylcholine in the synaptic cleft

Explanation: It stops continuous stimulation. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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16. The Venus fly trap gains nitrogen from insects because it

  1. has no roots
  2. needs protein for energy only
  3. grows in nitrogen-poor soils
  4. cannot photosynthesise

Answer: C) grows in nitrogen-poor soils

Explanation: Digestion supplies nitrogen compounds. AS & A Level Biology · Topic 15 Control and Coordination · 15.2 Control and coordination in plants

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17. The myelin sheath is formed by

  1. muscle fibres
  2. Schwann cells
  3. red blood cells
  4. neurones themselves

Answer: B) Schwann cells

Explanation: Schwann cells wrap the axon. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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18. In germinating barley, gibberellin stimulates the aleurone layer to produce

  1. ABA
  2. amylase
  3. auxin
  4. lipase

Answer: B) amylase

Explanation: Amylase digests endosperm starch. AS & A Level Biology · Topic 15 Control and Coordination · 15.2 Control and coordination in plants

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19. Compared with the nervous system, the endocrine system

  1. is faster
  2. uses electrical impulses
  3. acts more slowly and its effects last longer
  4. has precise local effects

Answer: C) acts more slowly and its effects last longer

Explanation: Hormones travel in blood. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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20. When a sarcomere contracts,

  1. all bands shorten
  2. the A band shortens
  3. actin filaments shorten
  4. the I band and H zone shorten but the A band stays the same

Answer: D) the I band and H zone shorten but the A band stays the same

Explanation: Filaments slide, they do not shorten. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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21. Saltatory conduction occurs in

  1. unmyelinated neurones only
  2. myelinated neurones, where impulses jump between nodes of Ranvier
  3. muscle fibres
  4. synapses

Answer: B) myelinated neurones, where impulses jump between nodes of Ranvier

Explanation: Myelin insulates internodes. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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22. The Venus fly trap closes when

  1. one hair is touched once
  2. it rains
  3. two trigger hairs are touched within a short time
  4. light falls on it

Answer: C) two trigger hairs are touched within a short time

Explanation: Two stimuli prevent false triggers. AS & A Level Biology · Topic 15 Control and Coordination · 15.2 Control and coordination in plants

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23. In the acid growth hypothesis, auxin causes

  1. cells to divide faster
  2. stomata to close
  3. the cell wall to thicken
  4. proton pumps to acidify the cell wall, loosening it

Answer: D) proton pumps to acidify the cell wall, loosening it

Explanation: Low pH activates expansins. AS & A Level Biology · Topic 15 Control and Coordination · 15.2 Control and coordination in plants

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24. In a taste bud, depolarisation of the receptor cell by salt is caused by

  1. K⁺ leaving
  2. acetylcholine
  3. Na⁺ ions entering through channels
  4. glucose binding

Answer: C) Na⁺ ions entering through channels

Explanation: Na⁺ entry produces a receptor potential. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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25. Sensory receptors are described as transducers because they

  1. convert the energy of a stimulus into electrical energy
  2. conduct impulses to muscles
  3. produce hormones
  4. store neurotransmitters

Answer: A) convert the energy of a stimulus into electrical energy

Explanation: Receptors convert stimulus energy. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

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