Which hormone is responsible for the development of female secondary sexual characteristics such as breast development, menstrual cycle, and widening of hips?

Keratin is a fibrous protein that provides strength and protection to the body, particularly in the skin, hair, and nails.

It is found in epithelial tissue, which covers the body’s surface and lines its internal organs and cavities.

Choice B.

Collagen is incorrect because collagen is a fibrous protein that provides strength and support to connective tissues such as tendons, ligaments, and cartilage.

Choice C.

Elastin is incorrect because elastin is a protein that provides elasticity to tissues such as skin and blood vessels.

Choice D.

Actin is incorrect because actin is a protein that plays a role in muscle contraction and cell movement.

Pattern recognition receptors (PRRs) are a class of receptors that can directly recognize the specific molecular structures on the surface of pathogens.

PRRs play a crucial role in the proper function of the innate immune system and are germline-encoded host sensors, which detect molecules typical for the pathogens.

Choice B is incorrect because cytokines are not receptors but rather signaling molecules that regulate immunity.

Choice C is incorrect because chemokines are not receptors but rather signaling molecules that attract immune cells to sites of infection.

Choice D is incorrect because T cells are not receptors but rather white blood cells that assist B cells or directly kill infected cells.