Free Human Body and Health MCQs with Answers

541. What is the addictive drug in tobacco ______________?

• A. Ethanol
• B. Nicotine
• C. Ammonia
• D. Tar

Explanation: Nicotine is the tobacco alkaloid that produces dependence by stimulating the brain's reward pathways. Tar is a harmful mixture of smoke residues, while ammonia and ethanol are not the addictive drug asked for.

542. How does smoking cigarettes impact the red blood cells?

• A. Decreases their ability to congeal
• B. Decreases their ability to carry oxygen
• C. Decreases their ability to reach their typical life duration
• D. Decreases their ability to cleanse wounds

Explanation: Carbon monoxide in cigarette smoke binds strongly to haemoglobin, displacing oxygen and reducing the blood's oxygen-carrying capacity. This is why smoking can deprive tissues of oxygen even when red-cell numbers are not immediately reduced.

543. Which of the following conditions related to smoking involves damage to the alveoli sacs?

• A. Lung Cancer
• B. Atherosclerosis
• C. Emphysema
• D. Asthma

Explanation: Emphysema destroys and weakens the walls of the alveoli, reducing the surface available for oxygen and carbon dioxide exchange. Lung cancer, atherosclerosis and asthma affect the lungs or blood vessels differently.

544. Periodontics deals with _____________?

• A. Surgery of spine
• B. Stomach disorders
• C. Ligaments restoration
• D. Dentistry
• E. Heart attacks

Explanation: Periodontics is the branch of dentistry concerned with the gums and other tissues supporting the teeth. It is not related to spinal surgery, stomach disorders or heart attacks.

545. Circadian Rhythm refers to _____________?

• A. Planetary movements
• B. Formation of galaxies
• C. Human body cycles
• D. Calisthenics

Explanation: A circadian rhythm is an approximately 24-hour biological cycle, such as the sleep-wake cycle and daily changes in body temperature. It describes biological timing, not planetary or galactic movement.

546. Which of the following is a mammal?

• A. Ostrich
• B. Crocodile
• C. Platypus
• D. Duck

Explanation: The platypus is a mammal even though it lays eggs, because it has hair and produces milk for its young. Ostriches and ducks are birds, while crocodiles are reptiles.

547. The protein content of edible portion of egg is___________?

• A. 13 %
• B. 13.3%
• C. 14 %
• D. 14.5%Downloading Digital Educational Resources

Explanation: The edible portion of a hen's egg contains about 13.3 percent protein, though the exact value can vary slightly with egg size and composition.

548. Alzheimer's disease in human beings is characterized by the degeneration of _______

• A. Kidney cells
• B. Nerve cells
• C. Liver cells
• D. Spleen cells

Explanation: Alzheimer's disease progressively damages neurons, especially in brain regions involved in memory and thinking. Kidney, liver and spleen cells are not the defining target of this disease.

549. Which among the following is responsible for producing color of human skin ___?

• A. Insulin
• B. Vitamin K
• C. Melanin
• D. DNA

Explanation: Melanin is the pigment produced by melanocytes that gives skin its colour and helps protect it from ultraviolet radiation. Insulin and vitamin K have metabolic and blood-clotting roles, while DNA carries genetic information.

550. In which part of the eye lies the pigment that decides the colour of the eyes of a person___?

• A. Retina
• B. Iris
• C. Cornea
• D. Pupal

Explanation: The iris contains melanin-producing cells, and the amount and distribution of this pigment determine eye colour. The retina detects light, whereas the cornea is the transparent front surface of the eye.