Correct Answer: B

Rationale: The myelin sheath serves to insulate neurons and accelerate the transmission of electrical signals along the axon. This insulation helps in the efficient conduction of nerve impulses by preventing signal loss or leakage. Choice A is incorrect because the myelin sheath does not transmit electrical impulses itself but rather helps in the conduction. Choice C is incorrect as the myelin sheath is not responsible for producing neurotransmitters. Choice D is also incorrect as the primary function of the myelin sheath is not to protect the neuron from damage. Therefore, the correct answer is B, as it accurately describes the function of the myelin sheath in a neuron.

Correct Answer: A

Rationale: Cytokinesis is the correct term for the division of the cytoplasm during cell division. It is the final stage of cell division, following either mitosis or meiosis, where the cytoplasm of a parent cell is divided into two daughter cells. Mitosis is the process of nuclear division, while meiosis is a type of cell division that results in four daughter cells with half the number of chromosomes of the parent cell. Apoptosis, on the other hand, is programmed cell death and not the division of the cytoplasm.

Correct Answer: B

Rationale: Enzymes act as biological catalysts that speed up chemical reactions in the body. They lower the activation energy required for reactions to occur, thus facilitating processes like digestion, metabolism, and other essential functions. Choice A is incorrect as the transportation of oxygen is primarily carried out by red blood cells. Choice C is incorrect as the regulation of body temperature involves mechanisms such as sweating and shivering. Choice D is incorrect as energy storage is mainly performed by molecules like glycogen and triglycerides.

Correct Answer: C

Rationale: The correct answer is C: Immune cells. Immune cells, such as macrophages, contain many lysosomes for breaking down pathogens. Lysosomes are organelles responsible for digestion and waste removal within the cell, and immune cells require a high concentration of lysosomes to aid in their defense mechanisms against pathogens. Choice A, Cardiac cells, is incorrect because lysosomes are not primarily abundant in cardiac cells. Choice B, Glandular cells, is incorrect as well since lysosomes are not specifically concentrated in glandular cells. Choice D, Neurons, is also incorrect because while lysosomes are present in neurons, they are not typically found in high concentrations compared to immune cells.

Correct Answer: B

Rationale: The correct answer is B: Capillaries. Capillaries are the smallest blood vessels that connect arterioles (small arteries) with venules (small veins). They enable the exchange of oxygen, nutrients, and waste products between the blood and tissues. Arterioles are small arteries that carry blood away from the heart, while venules are small veins that carry blood towards the heart. Veins are larger blood vessels that transport blood back to the heart. Therefore, capillaries specifically serve as the vessels responsible for the exchange of substances between the blood and body tissues.