From which type of tissue is the myelin sheath derived, a fatty substance that insulates nerve fibers?

Correct Answer: C

Rationale: The myelin sheath, a fatty substance that insulates nerve fibers, is derived from nervous tissue, specifically glial cells. Glial cells, including oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system, are responsible for producing the myelin sheath that surrounds and insulates nerve fibers, aiding in the conduction of nerve impulses. Epithelial tissue (Choice A), Muscle tissue (Choice B), and Connective tissue (Choice D) are not responsible for producing the myelin sheath; instead, nervous tissue (glial cells) plays this crucial role.

Correct Answer: B

Rationale: Sunscreen works by absorbing UV rays and converting them to heat. This mechanism helps to prevent the UV rays from penetrating the skin and causing damage such as sunburn, premature aging, and skin cancer. Reflecting UV rays away from the skin (option A) is not the primary function of sunscreen. While sunscreen does block UV rays, it does not do so completely (option C) as some UV rays may still penetrate the skin. Sunscreen does not stimulate melanin production (option D) as a means of protecting the skin from UV rays.

Correct Answer: B

Rationale: The correct answer is 'Remodeling.' Remodeling is the process of breaking down and rebuilding bone tissue. Ossification is the process of bone formation, not breaking down and rebuilding bone tissue. Calcification involves the deposition of calcium salts in tissues, but it is not specifically related to breaking down and rebuilding bone tissue. Osteoporosis is a condition characterized by decreased bone density leading to increased bone fragility, not the process of breaking down and rebuilding bone tissue.

Correct Answer: B

Rationale: Skeletal muscles are attached to bones by tough connective tissues called tendons. Tendons are strong, fibrous cords that connect muscles to bones, allowing for movement and stability in the body. Ligaments (option A) connect bones to other bones, not muscles to bones. Cartilage (option C) is firm and flexible connective tissue found in various parts of the body, but it does not attach muscles to bones. Fascia (option D) is a connective tissue that surrounds muscles, providing support and protection, but it does not directly attach muscles to bones.

Correct Answer: B

Rationale: Creatine phosphate is utilized as an immediate energy source for short bursts of muscle activity. When it breaks down, it yields lactic acid as a byproduct. Lactic acid accumulation during intense exercise can lead to muscle fatigue and soreness. Therefore, the correct answer is lactic acid. The other choices are incorrect: Glucose is a different energy source derived from carbohydrates; Carbon dioxide is a waste product of cellular respiration, not specifically from creatine phosphate breakdown; Creatine is the precursor compound to creatine phosphate and is not the breakdown product.