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CAIE A-Level Biology A2 15.1 Control and Coordination in Mammals Questions

Practise mammalian control and coordination by tracing sensory signals and synapses, then following neuromuscular activation into sarcomere contraction.

Syllabus
2028–2030
Course
Biology 9700
Level
A2

Exam points

  • Compare hormone signals in blood with neurone impulses by speed, duration and target range.
  • Identify sensory, motor and intermediate neurones by structure and direction of signalling.
  • Trace a taste-bud stimulus through receptor depolarisation, transmitter release and a sensory impulse.
  • Explain resting and action potentials using Na+ entry, K+ exit, threshold and pump restoration.
  • Use refractory phases to explain one-way impulses and the maximum firing frequency.
  • Explain fast myelinated conduction as saltatory transmission between nodes of Ranvier.
  • Trace Ca2+-triggered ACh release, receptor binding, Na+ entry and acetylcholinesterase breakdown.
  • Explain how neuromuscular junctions and T-tubules trigger Ca2+ release from the sarcoplasmic reticulum.
  • Identify sarcomere landmarks such as Z-lines and A-bands in micrographs or diagrams.
  • Explain sliding-filament contraction through Ca2+, troponin, tropomyosin and ATP-driven cross-bridges.

Covered syllabus points

15.1.1—Endocrine system features15.1.2—Nervous and endocrine systems15.1.3—Sensory, motor and intermediate neurones15.1.4—Sensory receptor cells15.1.5—Action potential sequence15.1.6—Membrane potential changes15.1.7—Rapid transmission in myelinated neurone15.1.8—Refractory period15.1.9—Cholinergic synapse structure and function15.1.10—Muscle contraction stimulation15.1.11—Striated muscle ultrastructure15.1.12—Sliding filament model of contraction

Question 1

[Maximum number: 6]

The passage outlines the endocrine system.
Complete the passage by using the most appropriate scientific terms.
The endocrine system consists of tissues and ,
which secrete hormones such as insulin, glucagon and antidiuretic hormone (ADH). Glucagon only affects target cells that have complementary receptors, which are located on the . Glucagon binds to these receptors and this leads to the production of a , which transfers the signal throughout the cytoplasm. The target cells for insulin are in the liver, and adipose tissue. The target cells for ADH are those of the distal convoluted tubule and the of the kidney nephron. These hormones are involved in , which is the maintenance of a constant internal environment.

Question 2

[Maximum number: 4]

Outline the differences between the endocrine system and the nervous system.

Question 3

[Maximum number: 15]

Question (a)

(a)

Fig. 8.1 is a diagram of a sensory neurone.

Fig. 8.1

Fig. 8.1

[ 3 ]

Question (i)

(i)

Name the type of cell represented by cell A.

[ 1 ]

Question (ii)

(ii)

Name a type of cell that forms a synapse with structure B.

[ 1 ]

Question (iii)

(iii)

Name the cells that form the myelin sheath.

[ 1 ]

Question (b)

(b)

State and explain the differences in the transmission of impulses between myelinated and unmyelinated neurones.

Figure for Question (b) — CAIE A-Level Biology A2
Figure for Question (b) — CAIE A-Level Biology A2
[ 4 ]

Question (c)

(c)

Opioids are therapeutic drugs that are used to relieve pain. Morphine is an example of an opioid. It affects the functioning of synapses.

Fig. 8.2 is a diagram of a cholinergic synapse.

Fig. 8.2

Fig. 8.2

[ 8 ]

Question (i)

(i)

With reference to Fig. 8.2, describe the differences between ion channel A and ion channel B.

[ 2 ]

Question (ii)

(ii)

Morphine binds to the opioid receptor in the presynaptic membrane. This stops the ion channel A from opening.

Suggest and describe the effects of the binding of morphine to this opioid receptor on the functioning of the cholinergic synapse.

[ 4 ]

Question (iii)

(iii)

Morphine also binds to the opioid receptor in the postsynaptic membrane. This results in the opening of ion channel C, allowing potassium ions to diffuse out of the cell.

Suggest how this would affect the synapse.

Figure for Question (iii) — CAIE A-Level Biology A2
Figure for Question (iii) — CAIE A-Level Biology A2
[ 2 ]
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