Connective tissue provides support and connects other tissues. What is the main component that gives connective tissue its strength?

Correct Answer: A

Rationale: Collagen fibers are the main component that gives connective tissue its strength. Collagen is a fibrous protein that provides structural support and tensile strength to connective tissues, allowing them to withstand stretching and tension. Epithelial cells, nerve cells, and blood cells are not the main components responsible for the strength of connective tissue. Epithelial cells are specialized for covering and lining surfaces, nerve cells transmit signals, and blood cells are involved in various functions like oxygen transport and immune response, but they do not provide the structural strength typical of collagen fibers in connective tissue.

Correct Answer: C

Rationale: Dandruff is primarily caused by an overgrowth of a specific type of fungus called Malassezia on the scalp. This fungus feeds on the natural oils produced by the hair follicles, leading to irritation and flaking of the scalp skin. Choice A is incorrect because excessive sebum production can contribute to oily dandruff, but it is not the primary cause of dandruff. Choice B is incorrect as bacterial infection primarily causes scalp folliculitis, not dandruff. Choice D is incorrect as dandruff is not primarily caused by a lack of proper skin hydration.

Correct Answer: B

Rationale: The correct answer is the reticular layer. This layer is the outermost layer of the dermis that contains abundant collagen and elastin fibers, providing elasticity to the skin. The papillary layer is located beneath the epidermis and is responsible for supplying nutrients to the epidermis, not the outermost layer. The stratum basale is the deepest layer of the epidermis where new skin cells are produced, not part of the dermis. The stratum corneum is the outermost layer of the epidermis composed of dead skin cells, not a layer of the dermis.

Correct Answer: C

Rationale: The medullary cavity is the correct answer. It is the central cavity within the shafts of long bones where red bone marrow is located, responsible for the production of red blood cells. The periosteum is the outer layer of bone that provides nourishment and participates in bone repair. The diaphysis refers to the shaft of a long bone that contains yellow bone marrow. The epiphysis is the end of a long bone involved in joint articulation and contains red bone marrow in children for blood cell production.

Correct Answer: C

Rationale: Synergistic muscles are groups of muscles that work together in a coordinated manner to produce a specific movement. They synchronize their actions to achieve a common goal efficiently. In contrast, antagonistic muscles work in opposing directions, and agonistic muscles, also known as prime movers, are responsible for initiating a movement. Flexors and extensors represent muscles that perform contrasting actions around a joint, such as bending and straightening. Therefore, the correct answer is C - 'Synergistic muscles,' as they collaborate to facilitate a specific movement, unlike the other choices which describe different muscle functions within the body.