Free Receptors MCQs with Answers

21. The part of the brain that acts as a relay bridge between regions and helps regulate the rhythm of breathing is the

• A. cerebellum
• B. pons
• C. thalamus
• D. hypothalamus

Explanation: The pons, whose name means bridge, connects the cerebrum and cerebellum with the medulla and contains centres that smooth the breathing rhythm. The thalamus relays sensory impulses, a different kind of bridging role.

22. The centres for visual and auditory reflexes, such as turning the head towards a sudden sound, are located in the

• A. cerebrum
• B. cerebellum
• C. midbrain
• D. medulla oblongata

Explanation: The midbrain receives input from the eyes and ears and coordinates these quick orienting reflexes. Conscious seeing and hearing happen higher up in the cerebrum, while the medulla governs heart rate and breathing.

23. Reasoning, judgement, planning and personality are associated mainly with the

• A. occipital lobe
• B. temporal lobe
• C. parietal lobe
• D. frontal lobe

Explanation: The frontal lobes, especially the prefrontal cortex, handle higher mental functions, and damage there famously alters personality. The occipital lobe processes vision and the temporal lobe hearing and memory, so function maps onto lobe.

24. The three membranes that cover and protect the brain and spinal cord are collectively called the

• A. meninges
• B. ventricles
• C. choroid plexuses
• D. myelin layers

Explanation: The dura, arachnoid and pia mater cushion the CNS and enclose the cerebrospinal fluid, and their infection causes meningitis. Ventricles are the fluid filled cavities inside the brain, not its coverings.

25. A drunk person walks unsteadily and cannot coordinate movements because alcohol mainly affects the

• A. medulla oblongata
• B. cerebellum
• C. hypothalamus
• D. pituitary gland

Explanation: The cerebellum fine tunes posture, balance and the timing of voluntary movement, so its depression by alcohol produces staggering and clumsiness. The medulla keeps the heart and lungs running, which is why severe poisoning, not drunkenness, threatens life.

26. Hormones are best described as

• A. enzymes that speed up metabolism
• B. waste products of the endocrine glands
• C. chemical messengers carried in the blood to target organs
• D. electrical signals sent along nerves

Explanation: Endocrine glands secrete hormones directly into the blood, which delivers them everywhere, but only cells with the right receptors respond. This slow, widespread chemical signalling complements the fast, wired signalling of the nervous system.

27. The pituitary gland is called the master gland because it

• A. is the largest endocrine gland
• B. sits outside the brain
• C. secretes digestive enzymes
• D. controls the secretion of several other endocrine glands

Explanation: Pituitary hormones such as TSH and ACTH direct the thyroid and adrenal cortex, and its link with the hypothalamus places it at the top of many control chains. Size is irrelevant; control is what earns the title.

28. Excess secretion of growth hormone during childhood results in

• A. gigantism
• B. dwarfism
• C. cretinism
• D. diabetes

Explanation: Before the bones stop growing, too much growth hormone drives the long bones to extraordinary length, producing gigantism. Deficiency instead causes dwarfism, and after the growth plates close, excess hormone thickens bones in acromegaly rather than lengthening them.

29. Thyroxine, the hormone of the thyroid gland, primarily controls the

• A. concentration of glucose in the blood
• B. rate of metabolism and heat production of the body
• C. amount of calcium in the bones
• D. volume of urine produced

Explanation: Thyroxine sets the basal metabolic rate of nearly every cell, which is why an overactive thyroid causes weight loss and heat intolerance. Blood glucose is governed by insulin and glucagon, and urine volume by ADH.

30. Adrenaline released from the adrenal medulla prepares the body for

• A. sleep and digestion
• B. long term growth
• C. emergency action, the fight or flight response
• D. the production of eggs

Explanation: Adrenaline raises heart rate, blood glucose and blood flow to muscles while slowing digestion, equipping the body for sudden exertion. Rest and digest is the job of the parasympathetic system, the functional opposite.