The openings on the leaf surface for gas exchange are called: MCQ with Answer and Explanation

Explanation:
Biotin (vitamin B₇) is a coenzyme for carboxylases, e.g., pyruvate carboxylase, acetyl-CoA carboxylase. It is involved in gluconeogenesis and fatty acid synthesis. Deficiency is rare but can occur with raw egg white consumption.

Explanation:
Telomerase is a ribonucleoprotein enzyme that adds repetitive nucleotide sequences to the ends of chromosomes (telomeres), preventing them from shortening during DNA replication. It is highly active in germ cells, stem cells, and most cancer cells, granting them replicative immortality. In most normal somatic cells, telomerase is inactive, leading to gradual telomere shortening and cellular aging.

Explanation:
Biotin is a coenzyme for carboxylation enzymes, including pyruvate carboxylase (gluconeogenesis) and acetyl-CoA carboxylase (fatty acid synthesis). Thiamine (B₁) is for decarboxylation, riboflavin (B₂) for redox, folate (B₉) for one-carbon transfers. Biotin is often bound to lysine in enzymes.