Assertion (A): Xerophytes have a thick cuticle. Reason (R): Thick cuticle reduces water loss in dry environments. MCQ with Answer and Explanation

Explanation:
Agrobacterium tumefaciens is a soil bacterium that naturally transfers part of its Ti (tumor-inducing) plasmid DNA (T-DNA) into the plant genome, causing crown gall disease. Scientists have harnessed this capability by replacing the tumor-causing genes with desirable genes, making it a vector for creating transgenic plants. E. coli vectors are used for bacterial transformation.

Explanation:
Vitamin A is essential for the formation of rhodopsin in the retina; its deficiency causes night blindness. Vitamin B1 (thiamine) deficiency leads to beriberi, characterized by nerve and heart issues. Vitamin K, not Vitamin C, is essential for the synthesis of blood clotting factors like prothrombin. Vitamin C is essential for collagen synthesis and immunity. Thus, statements 1 and 2 are correct.

Explanation:
Peroxisomes are single-membrane organelles involved in oxidative reactions, not plastids. Plastids (chloroplasts, chromoplasts, leucoplasts) are double-membrane organelles found in plants and algae, involved in photosynthesis, storage, and pigmentation. Chloroplasts contain chlorophyll, chromoplasts carotenoids, leucoplasts are colorless storage plastids.