The substance that gives skin its pigment and protects against UV radiation is:
A. Melanin
B. Keratin
C. Collagen
D. Elastin
Answer: Option A
Solution (By JKExamLibrary)
Melanin, produced by melanocytes in the epidermis, is the primary pigment determining skin, hair, and eye color. It absorbs UV radiation, protecting DNA from damage. Keratin is a structural protein in hair and nails, collagen provides connective tissue strength, elastin elasticity. Albinism results from melanin deficiency.
Explanation:
The cell theory states that the cell is the fundamental unit of structure and function. Not all cells have a nucleus (prokaryotes), prokaryotes lack mitochondria, viruses are not cells.
Explanation:
Producers (autotrophs) capture solar energy and form the base of the energy pyramid; they contain the largest amount of energy. Only about 10% of energy is transferred to the next trophic level (primary consumers). Energy decreases at each successive level, making producers the most energy-rich.
Explanation:
Peyer's patches are organized lymphoid follicles (aggregated lymphoid nodules) located in the mucosa and submucosa of the small intestine, most abundantly in the ileum (the distal part). They are a crucial component of the gut-associated lymphoid tissue (GALT) and play a vital role in monitoring intestinal bacteria populations, preventing the growth of pathogenic bacteria, and training the immune system to recognize antigens.
No comments yet. Be the first to start the discussion!