Which of the following statements about animal tissues is correct? MCQ with Answer and Explanation

Explanation:
Vitamin C is a cofactor for the enzyme tyrosinase, which is involved in melanin synthesis. Vitamin A is for vision, B₆ for amino acid metabolism, D for calcium.

Explanation:
The Islets of Langerhans are the endocrine (hormone-producing) portions of the pancreas. They are clusters of cells scattered throughout the pancreatic tissue, comprising about 1-2% of the pancreas's mass. They contain several cell types, primarily alpha cells (secreting glucagon), beta cells (secreting insulin), delta cells (secreting somatostatin), and F cells (secreting pancreatic polypeptide). These hormones are crucial for regulating blood glucose levels.

Explanation:
Nitrification is a two-step process in the nitrogen cycle where ammonia is oxidized to nitrates. First, ammonia (NH3) is converted to nitrites (NO2-) by bacteria like Nitrosomonas. Then, nitrites are converted to nitrates (NO3-) by bacteria like Nitrobacter. Nitrates are the primary form of nitrogen absorbed by plants. Denitrification is the reverse process, converting nitrates back to nitrogen gas.