15 extra multiple-choice questions for Nervous System (10th Standard Science, Samacheer Kalvi), beyond the ones printed in the textbook — each with the correct option highlighted and a clear, worked explanation. Free to read in English and Tamil.
Q1
Which of the following components of the nervous system consists of non-exciting, supporting cells that do not initiate or conduct nerve impulses?
- A. Neurons
- B. NeurogliaCorrect
- C. Nerve fibres
- D. Ganglia
Explanation. Neuroglia, also known as glial cells, are non-exciting supporting cells of the nervous system. Unlike neurons, they do not initiate or conduct electrical nerve impulses.
Q2
Unipolar neurons, in which only a single nerve process arises from the cyton, are typically found in which of the following?
- A. Retina of the eye
- B. Early human embryosCorrect
- C. Cerebral cortex
- D. Olfactory epithelium
Explanation. Unipolar neurons possess a single process extending from the cell body. They are characteristically present in early embryonic stages but are absent in adult humans.
Q3
The axon of a neuron is covered by a protective myelin sheath, which is further enveloped by an outer layer of which type of cells?
- A. Glial cells
- B. Schwann cellsCorrect
- C. Purkinje cells
- D. Epithelial cells
Explanation. The myelin sheath surrounding the axon is covered by an outer cellular layer formed by Schwann cells, known as the neurilemma.
Q4
Which chemical substance is released from the synaptic knob of an axon terminal to transmit nerve impulses across a synapse?
- A. AcetylcholineCorrect
- B. Thyroxine
- C. Insulin
- D. Pepsin
Explanation. Acetylcholine is an important neurotransmitter released from synaptic knobs. It diffuses across the synaptic gap to initiate an electrical impulse in the next neuron.
Q5
Which of the following correctly describes the arachnoid membrane surrounding the human brain?
- A. Outermost thick fibrous membrane protecting the brain
- B. Middle thin vascular membrane providing a web-like cushionCorrect
- C. Innermost delicate membrane richly supplied with blood
- D. Protective bony cover formed by the bones of the cranium
Explanation. The arachnoid membrane is the middle meningeal layer. It is thin and vascular, offering a web-like cushion to protect the brain from mechanical injury.
Q6
The outer grey matter of the cerebral cortex exhibits folds forming elevations and depressions. What are these structural features called?
- A. Nodes and internodes
- B. Horns and roots
- C. Gyri and sulciCorrect
- D. Ventricles and canals
Explanation. Folds in the cerebral cortex create raised ridges called gyri and shallow grooves called sulci. These structures significantly increase the surface area of the brain.
Q7
Which region of the forebrain, situated in the cerebral medulla, serves as the major conducting and relay centre for sensory and motor signaling?
- A. Hypothalamus
- B. ThalamusCorrect
- C. Pons
- D. Cerebellum
Explanation. The thalamus is located in the cerebral medulla and acts as a central relay station, receiving and directing sensory and motor signals to appropriate brain regions.
Q8
The dorsal portion of the midbrain contains four rounded swellings called corpora quadrigemina. What primary function do they perform?
- A. Control of body temperature and water balance
- B. Regulation of sleep-wake cycle and digestion
- C. Control of visual and auditory reflexesCorrect
- D. Maintenance of posture and muscle coordination
Explanation. Corpora quadrigemina consist of four optic lobes on the dorsal side of the midbrain that regulate visual and hearing (auditory) reflex responses.
Q9
The cerebellum is the second largest part of the brain. It consists of two large lateral hemispheres connected by a central structure called what?
- A. Corpus callosum
- B. VermisCorrect
- C. Filum terminale
- D. Pons varolii
Explanation. The cerebellum comprises two lateral cerebellar hemispheres joined centrally by a narrow median structure called the vermis. It coordinates voluntary muscle movements.
Q10
In the human body, the spinal cord extends downwards from the medulla oblongata and tapers into a thin thread-like structure called what?
- A. Filum terminaleCorrect
- B. Cauda equina
- C. Central canal
- D. Posterior horn
Explanation. The lower end of the spinal cord tapers into a slender, non-nervous fibrous thread known as the filum terminale at the level of the first lumbar vertebra.
Q11
Which of the following is NOT a functional role played by Cerebrospinal Fluid (CSF) in the central nervous system?
- A. Acting as a shock-absorbing fluid against sudden jerks
- B. Supplying essential nutrients to brain tissue
- C. Initiating voluntary muscle contractions directlyCorrect
- D. Maintaining constant pressure within the cranium
Explanation. Cerebrospinal fluid protects against shocks, supplies nutrients, removes wastes, and maintains intracranial pressure. It does not directly initiate muscle contractions.
Q12
Which clinical instrument records electrical impulses generated by the brain to help diagnose seizures, epilepsy, and brain tumors?
- A. Electrocardiogram (ECG)
- B. Electroencephalogram (EEG)Correct
- C. Endoscope
- D. Stethoscope
Explanation. An Electroencephalogram (EEG) records the electrical activity and wave patterns of the brain, enabling doctors to detect neurological disorders like epilepsy.
Q13
In a spinal nerve, what is the correct path and direction of nerve impulses passing through the dorsal root?
- A. Motor impulses directed away from the spinal cord
- B. Sensory impulses directed towards the spinal cordCorrect
- C. Autonomic signals traveling to the heart
- D. Motor commands passing directly to effector muscles
Explanation. Each spinal nerve has a dorsal sensory root and a ventral motor root. Impulses in the dorsal root carry sensory information towards the spinal cord.
Q14
Which physiological response is triggered by the activation of the sympathetic division of the autonomic nervous system?
- A. Slowing down of the heartbeat
- B. Constriction of the pupils
- C. Dilation of the bronchi and acceleration of heartbeatCorrect
- D. Stimulation of digestive secretions and peristalsis
Explanation. The sympathetic nervous system prepares the body for emergency responses by accelerating heartbeat, dilating bronchi, and inhibiting digestive activities.
Q15
Human brain tissue consists of approximately 60 percent fat. Which vital molecules must be obtained through diet to maintain brain integrity?
- A. Essential Fatty Acids (EFAs)Correct
- B. Essential Amino Acids
- C. Saturated Triglycerides
- D. Complex Carbohydrates
Explanation. Essential Fatty Acids (EFAs) cannot be synthesized by the human body and must be obtained from dietary sources like fish, nuts, and leafy greens to support brain structure.
