Free Homeostasis MCQs with Answers

• A. Endotherms
• B. Ectotherms
• C. Heterotherms
• D. Homeotherms

Explanation: Ectotherms depend largely on environmental heat to regulate their body temperature, so fishes, most invertebrates and amphibians are…

• A. Elevation of temperature in cold conditions.
• B. Embracing the enzymes and other proteins and prevent their denaturation.
• C. Change the chemical nature of other proteins thus making them heat resistant.
• D. Help in evaporative cooling.

Explanation: Heat shock proteins act as molecular chaperones during heat stress by binding to vulnerable proteins, helping them retain their functional…

• A. Pigmentation.
• B. Respiration.
• C. Evaporative cooling.
• D. Excretion.

Explanation: Panting increases evaporation of water from the respiratory passages, and evaporation removes heat from the body.

• A. Providing insulation in cold environment.
• B. Providing insulation in hot environment
• C. Rapid heat production.
• D. Controlling heat production.Health

Explanation: Brown fat contains many mitochondria and uncoupling proteins that release energy from respiration as heat instead of storing it mainly as…

• A. Cerebrum
• B. Cerebellum
• C. Thalamus
• D. Hypothalamus

Explanation: The hypothalamus acts as the body's thermoregulatory centre by comparing blood temperature with a set point and coordinating sweating…

• A. Tropical rain forest
• B. Tundra
• C. Grass land
• D. Desert

Explanation: The kangaroo rat is adapted to deserts, where it survives with very little free water by obtaining water from seeds and producing highly…

• A. Activation of sweat glands
• B. Dilation of skin blood vessels
• C. Panting
• D. Thermogenesis

Explanation: Thermogenesis is increased heat production, such as by shivering and increased metabolic activity, and helps an animal maintain body…

• A. Taxonomy
• B. Physiology
• C. Morphology
• D. Anatomy

Explanation: Stomatal movement involves physiological changes in guard-cell turgor that regulate gas exchange and water loss.

• A. Vasodilation
• B. Activation of sweat glands
• C. Thermogenesis
• D. Evaporative cooling

Explanation: At high temperature, the body reduces thermogenesis, or heat production, because producing more heat would raise body temperature further.

• A. Flowering plants release chemicals that attract pollinators
• B. A plant releases acid from its roots to destroy competing species
• C. Auxins produced in the apical cells diffuse into the zone of elongation
• D. Carbon dioxide produced in respiration diffuses out of leaves by stomata

Explanation: The correct answer is Option D. Excretion in plants involves the removal of waste products.

• A. Blood of earthworms
• B. Haemolymph of insects
• C. Tissue fluid of flatworms
• D. Interstitial fluid of hydra

Explanation: Malpighian tubules are a type of excretory and osmoregulatory system found in insects and some arachnids.

• A. Atrial natriuretic factor
• B. Aldosterone
• C. ADH
• D. Renin

Explanation: ANF is released when blood pressure/volume increases; it reduces blood pressure by promoting sodium and water excretion.

• A. Descending limb is impermeable to water
• B. Ascending limb is permeable to water
• C. Descending limb is permeable to electrolytes
• D. Ascending limb is impermeable to water

Explanation: The ascending limb reabsorbs ions but not water, crucial for urine concentration.

• A. Distal convoluted tubule
• B. Proximal convoluted tubule
• C. Bowman's capsule
• D. Descending limb of Henle's loop

Explanation: PCT reabsorbs sodium actively along with water and other solutes.

• A. Renin
• B. Atrial Natriuretic Factor (ANF)
• C. Alcohol
• D. Caffeine

Explanation: Renin promotes sodium/water retention, reducing dilute urine formation.

• A. No change in urine
• B. No urine formation
• C. More diluted urine
• D. More concentrated urine

Explanation: PCT reabsorbs water and solutes; without it, urine is more diluted.

• A. Increase in aldosterone levels
• B. Increase in ADH levels
• C. Decrease in aldosterone levels
• D. Decrease in ADH levels

Explanation: Aldosterone enhances sodium reabsorption via sodium channels and Na⁺/K⁺ pumps.

• A. Ascending limb of Henle
• B. Distal convoluted tubule
• C. Proximal convoluted tubule
• D. Descending limb of Henle

Explanation: PCT reabsorbs most water, sodium, glucose, and amino acids.

• A. Juxtaglomerular cells to release renin
• B. Adrenal cortex to release aldosterone
• C. Adrenal medulla to release adrenaline
• D. Posterior pituitary to release vasopressin

Explanation: Low GFR triggers renin release to maintain blood pressure.

• A. Four chambered heart
• B. Internal fertilization
• C. Nucleated RBCs
• D. Ureotelic mode of excretion

Explanation: Both humans and frogs excrete nitrogen mainly as urea.