A drug that blocks only neurotransmitter receptors on post-synaptic membranes is added to a preparation that has both electrical and chemical synapses. Which result is expected?

Transmission stops at chemical synapses but continues at electrical ones

Transmission continues at both kinds, since release of transmitter is not affected

Transmission stops at electrical synapses but continues at chemical ones

Transmission stops at both kinds, since both types depend on neurotransmitter

An electrode placed inside an axon shows that the inner surface turns positive at a stimulated site. Which event directly causes this reversal?

Action of the sodium-potassium pump

Exit of negatively charged proteins

Neural Control and Coordination

7 NEET-UG practice questions on Neural Control and Coordination, part of Zoology. The first 7 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Medium
Match List-I with List-II. List-I (brain structure) A. Corpus callosum B. Thalamus C. Hypothalamus D. Corpora quadrigemina List-II (feature) I. Major coordinating centre for sensory and motor signalling II. Tract of nerve fibres connecting the two cerebral hemispheres III. Four round swellings on the dorsal midbrain IV. Control of body temperature and the urge for eating and drinking
1. AA-III, B-I, C-IV, D-II
2. BA-II, B-I, C-IV, D-III
3. CA-I, B-II, C-IV, D-III
4. DA-II, B-IV, C-I, D-III
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Answer: B · A-II, B-I, C-IV, D-III
The corpus callosum connects the two hemispheres. The cerebrum wraps around the thalamus, the coordinating centre for sensory and motor signalling. The hypothalamus controls body temperature and the urge for food and drink, and the corpora quadrigemina are four swellings on the dorsal midbrain.
- A: This swaps the corpus callosum and the corpora quadrigemina.
- C: This swaps the corpus callosum and the thalamus.
- D: This swaps the thalamus and the hypothalamus.
Remember this
Thalamus relays and coordinates; hypothalamus controls temperature, eating and drinking; corpus callosum links hemispheres.
Question 2 · Easy
Which part of the human brain contains the centres that control respiration, cardiovascular reflexes and gastric secretions?
1. AThalamus
2. BPons
3. CMedulla
4. DCerebellum
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Answer: C · Medulla
The medulla is connected to the spinal cord and contains centres that control respiration, cardiovascular reflexes and gastric secretions. Together with the midbrain and pons, it forms the brain stem.
- A: The thalamus is a major coordinating centre for sensory and motor signalling.
- B: The pons consists of fibre tracts that interconnect different regions of the brain.
- D: The cerebellum is noted for a convoluted surface with very many neurons.
Remember this
Medulla controls breathing, cardiovascular reflexes and gastric secretion; pons has fibre tracts linking brain regions.
Question 3 · Hard
A drug that blocks only neurotransmitter receptors on post-synaptic membranes is added to a preparation that has both electrical and chemical synapses. Which result is expected?
1. ATransmission continues at both kinds, since release of transmitter is not affected
2. BTransmission stops at electrical synapses but continues at chemical ones
3. CTransmission stops at chemical synapses but continues at electrical ones
4. DTransmission stops at both kinds, since both types depend on neurotransmitter
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Answer: C · Transmission stops at chemical synapses but continues at electrical ones
At a chemical synapse the signal crosses the synaptic cleft only when released neurotransmitter binds post-synaptic receptors, so the drug stops it. At an electrical synapse the membranes are in very close proximity and current flows directly from one neuron to the next, with no receptor involved.
- A: Release alone is not enough, as the transmitter must bind its receptor to open ion channels.
- B: This reverses which synapse depends on receptors.
- D: Electrical synapses use direct current flow, not neurotransmitter.
Remember this
Chemical synapses need neurotransmitter and receptors; electrical synapses pass current directly and are faster.
Question 4 · Medium
An electrode placed inside an axon shows that the inner surface turns positive at a stimulated site. Which event directly causes this reversal?
1. AAction of the sodium-potassium pump
2. BExit of negatively charged proteins
3. CRapid efflux of K⁺
4. DRapid influx of Na⁺
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Answer: D · Rapid influx of Na⁺
A stimulus makes the membrane at that site freely permeable to Na⁺. The rapid inflow of Na⁺ reverses the polarity, so the inner surface turns positive and the outer surface negative. This depolarised state is the action potential.
- A: The pump maintains the resting gradients and does not make this sudden reversal.
- B: The axoplasm's negatively charged proteins cannot cross the membrane.
- C: K⁺ efflux comes later and restores the resting polarity.
Remember this
Na⁺ influx depolarises; the later K⁺ efflux repolarises the membrane.
Question 5 · Medium
Which of the following statements about neurons are correct? A. Nissl's granules are present in the cell body. B. Synaptic knobs contain vesicles filled with neurotransmitter. C. Dendrites carry impulses away from the cell body. D. Bipolar neurons are found in the cerebral cortex. Choose the correct answer.
1. AA and D only
2. BA, B and C only
3. CA and B only
4. DA, B and D only
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Answer: C · A and B only
The cyton holds the cytoplasm with Nissl's granules, and the synaptic knobs hold synaptic vesicles with neurotransmitters, so A and B are correct. Dendrites carry impulses towards the cell body, so C is wrong. Bipolar neurons are found in the retina and multipolar ones in the cerebral cortex, so D is wrong.
- A: This rejects B and accepts D.
- B: This accepts C, which reverses the direction of conduction in dendrites.
- D: This accepts D, which places bipolar neurons in the cortex instead of the retina.
Remember this
Dendrites bring impulses in, axons carry them out; multipolar in cortex, bipolar in retina.
Question 6 · Easy
Arrange the following in order from the skull inward to the brain tissue. A. Arachnoid B. Cerebral cortex C. Pia mater D. Dura mater Choose the correct order.
1. AD, A, C, B
2. BA, D, C, B
3. CC, A, D, B
4. DD, C, A, B
Answer and explanation in LearnFree account
Question 7 · Medium
Given below are two statements: Statement I: At rest, the axonal membrane is more permeable to K⁺ than to Na⁺. Statement II: The sodium-potassium pump moves 3 Na⁺ into the axon for every 2 K⁺ it moves out. Choose the correct answer.
1. AStatement I is incorrect but Statement II is correct
2. BBoth Statement I and Statement II are incorrect
3. CStatement I is correct but Statement II is incorrect
4. DBoth Statement I and Statement II are correct
Answer and explanation in LearnFree account

Neural Control and Coordination

Which part of the human brain contains the centres that control respiration, cardiovascular reflexes and gastric secretions?

A drug that blocks only neurotransmitter receptors on post-synaptic membranes is added to a preparation that has both electrical and chemical synapses. Which result is expected?

An electrode placed inside an axon shows that the inner surface turns positive at a stimulated site. Which event directly causes this reversal?

Arrange the following in order from the skull inward to the brain tissue. A. Arachnoid B. Cerebral cortex C. Pia mater D. Dura mater Choose the correct order.

Given below are two statements: Statement I: At rest, the axonal membrane is more permeable to K⁺ than to Na⁺. Statement II: The sodium-potassium pump moves 3 Na⁺ into the axon for every 2 K⁺ it moves out. Choose the correct answer.