Which of the following infectious diseases can be caused by a protozoan parasite?

Correct Answer: B

Rationale: The correct answer is B: Malaria. Malaria is caused by Plasmodium, a protozoan parasite transmitted through the bite of infected mosquitoes. Measles and mumps are viral diseases caused by separate viruses. Mononucleosis, on the other hand, is caused by the Epstein-Barr virus, which is also a viral infection. Therefore, choices A, C, and D are incorrect as they are caused by viruses, not protozoa.

Correct Answer: B

Rationale: Smooth muscles are the correct answer as they are found in the walls of hollow organs such as the intestines and blood vessels. Cardiac muscles are specifically found in the heart and are responsible for its contractions. Skeletal muscles are attached to bones and control voluntary movements. Voluntary muscles are under conscious control, but this term is not a specific type of muscle like smooth, cardiac, or skeletal muscles.

Correct Answer: B

Rationale: Starch is a polysaccharide, not a monosaccharide, making choice A incorrect. Glucose, choice B, is the correct answer as it is a monosaccharide, the simplest form of sugar. Cellulose, choice C, is a polysaccharide like starch, not a monosaccharide. Sucrose, choice D, is a disaccharide composed of glucose and fructose, not a monosaccharide. Glucose, being a monosaccharide, is a single sugar unit that serves as a primary energy source for living organisms.

Correct Answer: D

Rationale: The correct answer is D, Thyroid. The thyroid gland is responsible for regulating metabolism by producing thyroid hormones. These hormones play a crucial role in controlling various metabolic processes in the body, including energy production and utilization. Choice A, Thymus, is not responsible for regulating metabolism but plays a role in the immune system. Choice B, Pituitary, regulates various hormones but not specifically focused on metabolism. Choice C, Pancreas, is involved in insulin production and blood sugar regulation but is not primarily responsible for regulating metabolism.

Correct Answer: C

Rationale: The spleen is the correct answer. The spleen is a vital organ in the immune system responsible for filtering pathogens from the blood. It contains specialized immune cells that aid in recognizing and eliminating harmful substances. Additionally, the spleen plays a role in recycling old red blood cells. Choices A, B, and D are incorrect. Lymph nodes primarily filter lymph fluid, not blood. Kidneys are involved in filtering waste and regulating fluid balance, not specifically filtering pathogens from the blood. The pancreas functions in hormone regulation and digestion, unrelated to filtering pathogens from the blood.