The essential fatty acids that cannot be synthesized by the human body and must be obtained from the diet are: MCQ with Answer and Explanation

Explanation:
Immunoglobulin A (IgA) is the primary antibody found in mucosal secretions, including saliva, tears, nasal secretions, breast milk (colostrum), and the respiratory and gastrointestinal tracts. It plays a crucial role in mucosal immunity by preventing the attachment of pathogens to epithelial cells, a process known as immune exclusion. IgG is the most abundant in blood, IgM is the first to be produced in an infection, and IgE is involved in allergies.

Explanation:
The bacterial cell wall is a rigid structure that provides shape and protection. It is primarily composed of peptidoglycan (also known as murein), a polymer consisting of sugars and amino acids. Gram-positive bacteria have a thick peptidoglycan layer, while Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane. Cellulose is in plant walls, and chitin is in fungal walls.

Explanation:
Follicle-stimulating hormone (FSH) from the anterior pituitary promotes the growth and maturation of ovarian follicles and stimulates estrogen secretion. LH triggers ovulation, estrogen proliferates endometrium, progesterone maintains it.