30. Epilepsy is primarily a disorder of which body structure?
[SSC MTS (7 Oct 2024, Shift 2)]
- (A) Brain cells and neural networks
- (B) Teeth and bones
- (C) Skin layers
- (D) Skeletal-muscle fibres alone
Answer: (A) Brain cells and neural networks
Explanation: Epilepsy is characterised by an enduring tendency to experience epileptic seizures arising from abnormal, excessive or synchronous neuronal activity in the brain. A seizure may cause changes in awareness, movement or sensation. It is a neurological rather than primarily muscular condition.
29. Match:
(a) cerebral cortex,
(b) hypothalamus,
(c) cerebellum,
(d) pons;
with
(1) temperature regulation,
(2) sensory perception,
(3) sleep–wake functions,
(4) posture and balance.
[TNPSC Group IV (2024)]
- (A) a-1, b-3, c-2, d-4
- (B) a-2, b-3, c-4, d-1
- (C) a-2, b-1, c-3, d-4
- (D) a-2, b-1, c-4, d-3
Answer: (D) a-2, b-1, c-4, d-3
Explanation: The cerebral cortex supports conscious sensory perception; the hypothalamus regulates temperature; the cerebellum coordinates posture and balance; and the pons contributes to sleep–wake regulation. Matching each structure with its dominant textbook role identifies the final sequence.
28. Which portion of the human brain plays the principal role in maintaining bodily balance?
[Kolkata Police SI Preliminary (28 Jan 2024)]
- (A) Cerebellum
- (B) Medulla oblongata
- (C) Thalamus
- (D) Midbrain
Answer: (A) Cerebellum
Explanation: The cerebellum combines vestibular, visual and proprioceptive input to adjust muscle activity and maintain equilibrium. It fine-tunes coordinated actions and posture. The thalamus is primarily a relay station; the medulla controls essential autonomic functions, and the midbrain serves other sensorimotor roles.
27. Which sequence correctly represents the pathway of a typical spinal reflex?
[UPSC CDS I, General Knowledge (16 Apr 2023)]
- (A) Receptor → sensory neuron → spinal relay neuron → motor neuron → effector
- (B) Receptor → sensory neuron → brain → relay neuron → motor neuron → effector
- (C) Receptor → motor neuron → spinal relay neuron → sensory neuron → effector
- (D) Receptor → motor neuron → brain → sensory neuron → effector
Answer: (A) Receptor → sensory neuron → spinal relay neuron → motor neuron → effector
Explanation: A receptor responds to a stimulus and passes information through a sensory neuron to spinal circuitry. A relay neuron commonly activates the appropriate motor neuron, which produces action in an effector muscle or gland. This local arrangement minimises response delay.
26. Which kind of cell is characteristically long and branched?
[SSC Selection Post, Matric Level (28 Jun 2023, Shift 1)]
- (A) Nerve cell
- (B) Columnar epithelial cell
- (C) White blood cell
- (D) Red blood cell
Answer: (A) Nerve cell
Explanation: A nerve cell has branched dendrites for receiving inputs and frequently a long axon for transmitting impulses. These structural specialisations support communication over considerable distances. Epithelial and blood cells have other shapes suited to covering surfaces or circulating through vessels.
25. The medulla oblongata belongs to which organ?
[MP Forest Guard / Jail Prahari (7 Jun 2023, Shift 1)]
- (A) Heart
- (B) Brain
- (C) Lungs
- (D) Stomach
Answer: (B) Brain
Explanation: The medulla oblongata is the lower segment of the brainstem, continuous with the spinal cord. It contains centres involved in respiration, cardiovascular regulation and protective reflexes. Although it influences functions of the heart and lungs, anatomically it belongs to the brain.
24. Which treatment principle improves neuromuscular signalling in myasthenia gravis?
[KVS PGT Biology (20 Feb 2023, Shift 1)]
- (A) Administration of adrenaline alone
- (B) Restriction of dietary protein
- (C) Use of an acetylcholinesterase inhibitor
- (D) Blocking all acetylcholine receptors
Answer: (C) Use of an acetylcholinesterase inhibitor
Explanation: Myasthenia gravis involves immune-mediated impairment of receptors at the skeletal neuromuscular junction. Acetylcholinesterase inhibitors reduce acetylcholine breakdown, increasing its availability at surviving receptors and improving muscle strength. Other immune-directed treatments may be needed depending on severity and clinical context.
23. Which nutrient helps prevent neural-tube defects involving a baby’s brain and spine?
[SSC MTS (12 Sep 2023, Shift 2)]
- (A) Vitamin E
- (B) Vitamin A
- (C) Vitamin C
- (D) Folic acid
Answer: (D) Folic acid
Explanation: Folic acid, the supplemental form of vitamin B9, is required during early development for proper neural-tube closure. Adequate intake around conception reduces the risk of serious defects such as spina bifida and anencephaly. The neural tube later forms central nervous structures.
22. Which ions are especially important in the electrical signalling of nerve cells?
[UPSC NDA II, General Ability Test (4 Sep 2022)]
- (A) Sodium alone
- (B) Potassium alone
- (C) Iron and calcium only
- (D) Sodium and potassium
Answer: (D) Sodium and potassium
Explanation: An action potential depends largely on sodium entering the neuron and potassium leaving it through voltage-gated channels. These movements change membrane voltage, allowing an impulse to propagate. The sodium–potassium ATPase maintains concentration gradients essential for repeated electrical signalling.
21. Which part of the ear converts sound-induced vibrations into electrical signals for the auditory pathway?
[UPSC NDA II, General Ability Test (4 Sep 2022)]
- (A) Auditory nerve alone
- (B) Cochlea
- (C) Eardrum alone
- (D) Eustachian tube
Answer: (B) Cochlea
Explanation: Specialised hair cells within the cochlea transform mechanical vibration into receptor signals and stimulate fibres of the auditory nerve. The eardrum conveys vibrations, while the Eustachian tube equalises pressure. The cochlea therefore performs the key sensory transduction step in hearing.
