Exams › NEET › Biology › Neural Control and Coordination
100 questions with worked solutions.
Q1. Afferent nerve fibre carries impulses from
Answer: receptor to central nervous system
Afferent nerve fibres are sensory fibres that carry impulses toward the central nervous system. They transmit information from receptors to the brain or spinal cord, unlike efferent fibres which carry commands away from the CNS.
Q2. Sensitive pigmented layer of eye is
Answer: retina
The retina is the eye’s light-sensitive layer, containing photoreceptors that convert light into nerve impulses. Cornea is the transparent front surface, sclerotic (sclera) is the tough outer coat, and iris controls pupil size.
Q3. How do parasympathetic neural signals affect the working of the heart?
Answer: Reduce both heart rate and cardiac output.
Parasympathetic stimulation, mainly through the vagus nerve, slows the SA node and reduces heart rate. With fewer beats per minute, cardiac output also falls because output depends on heart rate and stroke volume.
Q4. Nissl bodies are mainly composed of:
Answer: Free ribosomes and RER
Nissl bodies are aggregates of rough endoplasmic reticulum with free ribosomes, which give them their basophilic staining. They are specialized for protein synthesis in neurons.
Q5. Which of the following structures or regions is incorrectly paired with its functions?
Answer: Limbic system : consists of fibre tracts that interconnect different regions of brain; controls movement.
The limbic system is mainly involved in emotion, motivation, and memory, not as a set of fiber tracts connecting brain regions or controlling movement. That description fits the corpus callosum more closely, making option B the incorrect pairing.
Q6. Receptor sites for neurotransmitters are present on:
Answer: Post-synaptic membrane
Neurotransmitters cross the synaptic cleft and attach to specific receptor proteins on the postsynaptic membrane. This binding triggers a response in the receiving neuron or effector cell.
Q7. Which of the following regions of the brain is incorrectly paired with its function?
Answer: Cerebellum – language comprehension
The cerebellum is primarily involved in coordination, balance, and motor learning, not language comprehension. Language comprehension is mainly associated with cortical language areas in the cerebrum, so that pairing is incorrect.
Q8. Myelin sheath is produced by:
Answer: Schwann cells and Oligodendrocytes
Schwann cells form the myelin sheath around peripheral nerve fibers, while oligodendrocytes do the same in the central nervous system. The other listed cells do not produce myelin.
Q9. Destruction of the anterior horn cell of the spinal cord would result in loss of:
Answer: voluntary motor impulses
The anterior horn of the spinal cord contains lower motor neurons whose axons exit to innervate skeletal muscle. If these cells are destroyed, voluntary motor impulses cannot reach the muscles, causing flaccid weakness or paralysis.
Q10. A diagram showing axon terminal and synapse is given. Identify correctly at least two of A-D.
Answer: A-Neurotransmitter, B-Synaptic cleft
A neurotransmitter is the chemical released from synaptic vesicles at the axon terminal, and the synaptic cleft is the narrow gap between the presynaptic and postsynaptic cells. Those two labels therefore fit the diagram correctly.
Answer: B – Neurotransmitter; D – Receptor capsules
In a synapse, neurotransmitters are the molecules released from the presynaptic terminal into the synaptic cleft. Receptor capsules are located on the postsynaptic membrane and bind those neurotransmitters, so the labels B and D match those structures.
Q12. A sagittal section of human-brain is shown here. Identify at least two labels from A-D.
Answer: A – Cerebral hemispheres; B – Cerebellum
In a sagittal brain section, the cerebral hemispheres form the large upper part of the brain, while the cerebellum is the smaller, highly folded structure at the back and below the cerebrum. The labels A and B correspond to these two major regions.
Q13. When a neuron is in resting state i.e., not conducting any impulse, the axonal membrane is:
Answer: comparatively more permeable to K+ ions and nearly impermeable to Na+ ions
In a resting neuron, many K+ leak channels are open, so K+ crosses the axonal membrane much more readily than Na+. Na+ permeability is very low, which helps maintain the resting membrane potential.
Q14. During the propagation of a nerve impulse, the action potential results from the movement of:
Answer: Na+ ions from extracellular fluid to intracellular fluid
The rising phase of an action potential is caused by sodium ions entering the neuron from the extracellular fluid through voltage-gated Na+ channels. This inward Na+ movement depolarizes the membrane and produces the nerve impulse.
Q15. The nerve centres which control the body temperature and the urge for eating are contained in:
Answer: hypothalamus
The hypothalamus is the main homeostatic control center of the brain. It regulates body temperature and appetite, along with thirst, sleep, and other autonomic functions.
Q16. Which part of human brain is concerned with the regulation of body temperature?
Answer: Hypothalamus
The hypothalamus helps maintain homeostasis by regulating body temperature, hunger, thirst, and other automatic functions. It acts like the body’s thermostat, making it the correct choice.
Answer: First negative, then positive and again back to negative
At rest, the inner side of the nerve membrane is negative relative to the outside. During an impulse, sodium influx reverses the polarity so the inside becomes positive, and then potassium efflux restores the original negative state.
Q18. The human hind brain comprises three parts, one of which is:
Answer: Cerebellum
The hindbrain includes the medulla, pons, and cerebellum. The cerebellum is one of these three and is responsible for coordination, posture, and balance.
Q19. In a man, abducens nerve is injured. Which one of the following functions will be affected?
Answer: Movement of the eye ball
The abducens nerve (cranial nerve VI) innervates the lateral rectus muscle, which moves the eyeball laterally. Injury to this nerve therefore impairs eye movement, especially abduction.
Q20. Which one of the following pairs of structures distinguishes a nerve cell from other types of cells?
Answer: Perikaryon and dendrites
Perikaryon is the neuron’s cell body, and dendrites are the branched extensions that receive signals. These are distinctive features of nerve cells, unlike nucleus or mitochondria, which are found in many cell types.