50. Which statement about nervous tissue is incorrect?
[RRB Group D (9 Aug 2026, Shift 1; 2025 recruitment cycle)]
- (A) Nerve impulses travel along nerve fibres.
- (B) The spinal cord contains nervous tissue.
- (C) An axon is a long extension of a neuron.
- (D) The cells responsible for nerve impulses are called nephrons.
Answer: (D) The cells responsible for nerve impulses are called nephrons.
Explanation: Neurons, not nephrons, are the excitable signalling cells of nervous tissue. Nephrons are microscopic functional units of the kidneys. A neuron possesses a cell body and processes, including an axon, that help transmit information through the nervous system.
49. The brain and spinal cord are composed primarily of which tissue?
[SSC GD Constable (19 May 2026, Shift 3)]
- (A) Muscular tissue
- (B) Connective tissue
- (C) Nervous tissue
- (D) Epithelial tissue
Answer: (C) Nervous tissue
Explanation: The brain and spinal cord constitute the central nervous system and contain neurons supported by neuroglial cells. Nervous tissue detects, processes and conducts signals. Connective, muscular and epithelial tissues perform important functions but are not the primary functional tissue of these organs.
48. Which neurotransmitter do sympathetic preganglionic neurons release at autonomic ganglia?
[UPHESC Assistant Professor, Zoology (18 Apr 2026)]
- (A) Acetylcholine
- (B) Noradrenaline
- (C) Dopamine
- (D) Adrenaline
Answer: (A) Acetylcholine
Explanation: Preganglionic fibres of both sympathetic and parasympathetic divisions release acetylcholine onto nicotinic receptors in autonomic ganglia. Most sympathetic postganglionic fibres instead release noradrenaline at their target organs. Distinguishing the two neuronal stages is essential for understanding autonomic signalling.
47. Which chemical messenger is released by motor neurons at the skeletal neuromuscular junction?
[DSSSB MTS (26 Apr 2026, Shift 3)]
- (A) Adrenaline
- (B) Serotonin
- (C) Dopamine
- (D) Acetylcholine
Answer: (D) Acetylcholine
Explanation: Acetylcholine is released when an impulse reaches a motor axon terminal. It binds to receptors on the muscle end plate, producing depolarisation and initiating contraction. Acetylcholinesterase rapidly breaks down the transmitter so that the muscle is not continuously stimulated.
46. Blood-pressure control, salivation and vomiting are chiefly associated with the medulla in which brain division?
[SSC MTS 2025 examination (4 Feb 2026, Shift 3)]
- (A) Medulla in the hindbrain
- (B) Cerebrum in the midbrain
- (C) Spinal cord in the forebrain
- (D) Medulla in the midbrain
Answer: (A) Medulla in the hindbrain
Explanation: The medulla oblongata forms the lowest portion of the brainstem and is classically grouped with the hindbrain. It contains vital autonomic and reflex centres involved in cardiovascular control, breathing, swallowing and vomiting, many of which function without conscious direction.
45. Which nerve category is correctly matched with its usual point of origin?
[RRB Group D (24 Dec 2025, Shift 1)]
- (A) Cranial nerves — brain
- (B) Cranial nerves — spinal cord
- (C) Spinal nerves — heart
- (D) Spinal nerves — brain
Answer: (A) Cranial nerves — brain
Explanation: Cranial nerves arise from the brain or brainstem, whereas spinal nerves arise from the spinal cord. Together they belong largely to the peripheral nervous system. The distinction helps explain how sensory and motor information travels between central nervous tissue and organs.
44. Which group of organs and structures is formed from nervous tissue?
[RRB Group D (22 Dec 2025, Shift 2)]
- (A) Kidneys, liver and spleen
- (B) Lungs, heart and stomach
- (C) Bones, tendons and ligaments
- (D) Brain, spinal cord and nerves
Answer: (D) Brain, spinal cord and nerves
Explanation: The brain and spinal cord are the main organs of the central nervous system, while peripheral nerves link them with the body. All contain specialised nervous tissue. Its neurons conduct messages, and supporting glial cells maintain a suitable working environment.
43. Which route best represents a simple spinal withdrawal reflex?
[RRB Group D (21 Dec 2025, Shift 2)]
- (A) Receptor → spinal cord → motor neuron → muscle
- (B) Receptor → brain → spinal cord → muscle
- (C) Receptor → spinal cord → brain → muscle
- (D) Receptor → motor neuron → spinal cord → muscle
Answer: (A) Receptor → spinal cord → motor neuron → muscle
Explanation: In a simplified reflex pathway, a receptor detects the stimulus and sensory input reaches the spinal cord, where it activates a motor route to the muscle. An interneuron commonly participates. The brain receives information too, but need not initiate the immediate withdrawal.
42. During a reflex arc, which neurons initially carry information from receptors towards the central nervous system?
[RRB Group D (19 Dec 2025, Shift 1)]
- (A) Motor neurons
- (B) Relay neurons
- (C) Sensory neurons
- (D) Effector muscle fibres
Answer: (C) Sensory neurons
Explanation: Sensory, or afferent, neurons carry signals from receptors toward the spinal cord or brain. Interneurons then often link sensory input to motor output. Motor neurons carry commands away from the central nervous system, while muscle fibres act as effectors.
41. What chiefly enables communication between the central nervous system and organs elsewhere in the body?
[RRB Group D (12 Dec 2025, Shift 1)]
- (A) Spinal cord only
- (B) Voluntary muscles
- (C) Peripheral nervous system
- (D) Involuntary muscles
Answer: (C) Peripheral nervous system
Explanation: The peripheral nervous system includes nerves and ganglia outside the brain and spinal cord. It carries incoming sensory messages and outgoing motor instructions. Its somatic and autonomic components together connect the central nervous system with skeletal muscles, glands and internal organs.