Free Coordination and Control MCQs with Answers

51. Action potentials are conducted in one direction because

• A. The axon is myelinated
• B. Of the refractory period
• C. Of the all-or-none law
• D. Sodium channels are everywhere

Explanation: The refractory period (when Na+ channels are inactivated) prevents backward conduction, ensuring unidirectional propagation.

52. Myelination increases conduction velocity by

• A. Increasing axon diameter
• B. Saltatory conduction
• C. Increasing Na+ channels
• D. Decreasing resistance

Explanation: Myelin insulates the axon, allowing action potentials to jump between nodes of Ranvier (saltatory conduction), greatly increasing speed.

53. Neurotransmitters are released by

• A. Diffusion
• B. Exocytosis
• C. Endocytosis
• D. Osmosis

Explanation: Neurotransmitters are released by exocytosis of synaptic vesicles when Ca2+ enters the presynaptic terminal.

54. Acetylcholine is broken down by

• A. Acetylcholinesterase
• B. Monoamine oxidase
• C. COMT
• D. Peptidase

Explanation: Acetylcholinesterase in the synaptic cleft rapidly breaks down acetylcholine to terminate the signal.

55. The sympathetic nervous system

• A. Decreases heart rate
• B. Causes fight-or-flight response
• C. Stimulates digestion
• D. Constricts pupils

Explanation: The sympathetic division mediates fight-or-flight responses: increased heart rate, dilated pupils, inhibited digestion.

56. Which neurotransmitter is inhibitory in the CNS?

• A. Glutamate
• B. GABA
• C. Dopamine
• D. Serotonin

Explanation: GABA (gamma-aminobutyric acid) is the main inhibitory neurotransmitter in the CNS, causing Cl- influx and hyperpolarization.

57. The cerebellum controls

• A. Memory
• B. Balance and coordination
• C. Heart rate
• D. Vision

Explanation: The cerebellum coordinates voluntary movements, balance, posture, and motor learning.

58. A reflex arc involves

• A. Only the brain
• B. Only the spinal cord
• C. Spinal cord and brain
• D. Receptor, spinal cord, effector

Explanation: A simple reflex arc involves receptor → sensory neuron → spinal cord integration → motor neuron → effector, without brain involvement.

59. Parkinson's disease involves deficiency of

• A. Serotonin
• B. Dopamine
• C. GABA
• D. Acetylcholine

Explanation: Parkinson's disease results from degeneration of dopaminergic neurons in the substantia nigra, causing tremors and rigidity.

60. The master endocrine gland is the

• A. Thyroid
• B. Adrenal
• C. Pituitary
• D. Pancreas

Explanation: The pituitary gland is called the master gland because its hormones regulate other endocrine glands.