20. Which combination of tissues is directly responsible for generating and controlling most body movements?
[RRB Group D (26 Sep 2022, Shift 3)]
- (A) Nervous and connective tissues only
- (B) Nervous and epithelial tissues
- (C) Muscular and connective tissues only
- (D) Nervous and muscular tissues
Answer: (D) Nervous and muscular tissues
Explanation: Nervous tissue sends and processes commands, while muscular tissue contracts to produce movement. Motor neurons activate skeletal muscles at neuromuscular junctions. Connective tissue supports and transmits force, but neural control and muscular contraction are the two principal active components.
19. Which autonomic division generally conserves energy and restores resting bodily conditions?
[MPTET Varg 3 (17 Mar 2022, Shift 2)]
- (A) Sympathetic division
- (B) Parasympathetic division
- (C) Both divisions have identical actions
- (D) Neither autonomic division
Answer: (B) Parasympathetic division
Explanation: The parasympathetic division is associated with rest, digestion and energy conservation. It commonly slows the heart, promotes digestive activity and supports glandular secretion. The sympathetic division instead generally prepares the organism for activity or stress, although effects vary by organ.
18. A synapse is a junction through which a nerve impulse commonly passes from where to where?
[RRB NTPC CBT I (15 Feb 2021, Shift 1)]
- (A) One neuron to another
- (B) Brain directly to bone
- (C) One epithelial cell to another
- (D) One endocrine gland to another
Answer: (A) One neuron to another
Explanation: At a chemical synapse, neurotransmitter released by a presynaptic neuron crosses the synaptic cleft and binds receptors on a target cell. Synapses connect neural circuits and permit modulation of signalling. Some synapses are electrical and transfer ionic current more directly.
17. What is the basic structural and functional unit of the nervous system?
[SSC JE Civil Engineering (23 Mar 2021, Evening)]
- (A) Neuron
- (B) Cerebellum
- (C) Cerebrum
- (D) Nephron
Answer: (A) Neuron
Explanation: The neuron is an excitable cell specialised for receiving, integrating and transmitting information. Its cell body, dendrites and axon work together to support communication. The nephron is instead the basic functional unit of the kidney, while cerebrum and cerebellum are brain structures.
16. Assess the statements:
1. Humans have 31 pairs of spinal nerves.
2. Sympathetic and parasympathetic functions are complementary.
Which statement is incorrect?
[DSSSB TGT Natural Science (8 Sep 2021, Shift 1)]
- (A) Only 1
- (B) Both 1 and 2
- (C) Only 2
- (D) Neither 1 nor 2
Answer: (D) Neither 1 nor 2
Explanation: Both statements are valid in the textbook sense. The 31 spinal-nerve pairs connect the spinal cord to different body regions. Sympathetic and parasympathetic divisions often have opposing yet coordinated effects, enabling autonomic regulation and internal physiological balance.
15. Which effect is NOT a usual parasympathetic response?
[UP TGT Biology (2021)]
- (A) Slowing the heartbeat
- (B) Accelerating the heartbeat
- (C) Stimulating salivary secretion
- (D) Stimulating intestinal peristalsis
Answer: (B) Accelerating the heartbeat
Explanation: Parasympathetic activity commonly reduces heart rate through vagal signalling and favours digestion and glandular secretions. Acceleration of the heartbeat is more typical of sympathetic stimulation. The exact autonomic influence depends on the organ and its receptor types.
14. A neuron possessing several dendrites and one axon is termed which type?
[DSSSB PGT Biology (16 Jul 2021, Shift 1)]
- (A) Multipolar neuron
- (B) Bipolar neuron
- (C) Unipolar neuron
- (D) Anucleate neuron
Answer: (A) Multipolar neuron
Explanation: Multipolar neurons contain one axon and multiple dendritic processes emerging from the soma. They are common among motor neurons and interneurons in the central nervous system. Bipolar neurons instead have two main processes and are found in certain sensory pathways.
13. Which structure contains nerve fibres carrying messages to and from the brain and coordinating many reflex actions?
[RRB NTPC CBT I (30 Dec 2020, Shift 1)]
- (A) Spinal cord
- (B) Heart
- (C) Rib cage
- (D) Skeletal muscles
Answer: (A) Spinal cord
Explanation: The spinal cord is a central nervous-system pathway linking the brain to peripheral nerves. It includes ascending sensory and descending motor tracts, as well as circuits mediating reflexes. Muscles respond to commands but do not replace the spinal cord’s coordinating function.
12. How many pairs of cranial nerves are conventionally identified in humans?
[MPPSC State Service, General Studies (2020)]
- (A) 8 pairs
- (B) 12 pairs
- (C) 25 pairs
- (D) 31 pairs
Answer: (B) 12 pairs
Explanation: Humans conventionally have twelve pairs of cranial nerves, labelled I to XII. They carry sensory, motor or mixed fibres and are connected with structures of the head, neck and some internal organs. By comparison, spinal nerves number thirty-one pairs.
11. Consider:
1. The brain helps regulate heartbeat.
2. The brain helps maintain balance.
Which statements are correct?
[UPPSC Civil Services Preliminary, GS I (2020)]
- (A) 1 only
- (B) 2 only
- (C) Both 1 and 2
- (D) Neither 1 nor 2
Answer: (C) Both 1 and 2
Explanation: Medullary autonomic centres contribute to cardiovascular regulation, and the cerebellum plays a major part in balance and posture. Thus different brain regions perform both functions. The brain is not limited to conscious thought; it also directs many automatic physiological activities.
