All Free Biology MCQs with Answers

2291. Formation of heat shock proteins in plants results in___________?

• 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 shape and preventing denaturation or aggregation. They do not raise the temperature in cold conditions. Students may choose option c because heat shock proteins are associated with heat tolerance, but they protect proteins rather than chemically changing them into heat-resistant proteins.

2292. Panting is a representative of which mechanism?

• 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. It is therefore a form of evaporative cooling, especially important in dogs and some other mammals. Students may choose respiration because panting involves rapid breathing, but its thermoregulatory purpose is cooling rather than gas exchange alone.

2293. Brown fat present in certain mammals is specialized in___________?

• 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 ATP. This allows rapid heat production during exposure to cold. Students may choose insulation because brown fat is a type of fat, but insulation is mainly provided by white fat and other body coverings.

2294. Which of the following acts as thermoregulator?

• 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, shivering and changes in blood flow. Students may choose the thalamus because its name is similar and it relays sensory information, but it does not control body temperature.

2295. Kangaroo rat most probably would be found in___________?

• 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 concentrated urine. Tropical rain forests, tundra and grasslands do not match its characteristic dry, sandy habitat. Students may choose c because kangaroo rats are terrestrial mammals, but their specialized water conservation indicates a desert environment.

2296. Which one of the following is most likely to occur in an animal during winter?

• 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 temperature in winter. The likely mistake is dilation of skin blood vessels, which increases heat loss and is more useful during overheating.

2297. The mechanism of stomatal movement is related to the branch of Biology called__________?

• 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. Morphology and anatomy study form and structure, so students may choose one of them because stomata are visible structures, but the question asks about their movement.

2298. In condition of high temperature, following does not occur or occurs at low level__________?

• 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. Vasodilation, sweating and evaporative cooling are increased to remove heat, so the common mistake is choosing vasodilation while confusing heat loss with heat production.

2299. Rabies is caused by: _____________?

• A. Paramyxovirus
• B. Rhinovirus
• C. Arbovirus
• D. Rhabdovirus

Explanation: Rabies is caused by rabies virus, a member of the genus Lyssavirus in the family Rhabdoviridae, whose virions are characteristically bullet-shaped. Students may choose an arbovirus because rabies can be transmitted by an animal bite, but arbovirus describes arthropod transmission and does not describe rabies. Thus, Rhabdovirus is the expected classification.

2300. Genome of viruses is composed of: ____________?

• A. DNA
• B. RNA
• C. Protein
• D. Both A & B

Explanation: Viruses have genomes made of nucleic acid, and different viruses may contain either DNA or RNA, although an individual virus normally contains one type rather than both. Students may choose DNA or RNA alone by generalizing from one virus group, but both types occur among viruses as a whole. Hence, option d is correct.