In gymnosperms like Pinus, the female gametophyte develops within the ovule and serves as the nutritive tissue for the developing embryo. Unlike angiosperms, where the nutritive tissue is the triploid endosperm formed after double fertilization, the gymnosperm nutritive tissue is haploid and forms before fertilization. Therefore, the edible part of a pine seed is the haploid female gametophyte.
Explanation:
Niacin (vitamin B₃) is the precursor of NAD⁺ and NADP⁺, essential electron carriers in redox reactions. Thiamine is TPP, riboflavin FAD, biotin for carboxylation.
Consider statements about vitamins: 1. Vitamin D is synthesized in the skin upon sunlight exposure. 2. Vitamin B12 is the only vitamin containing a metal ion. 3. Vitamin A is essential for blood clotting. Which are correct?
Explanation:
Vitamin D3 (cholecalciferol) is synthesized in the epidermis of the skin when 7-dehydrocholesterol is exposed to ultraviolet B (UVB) radiation from sunlight. Vitamin B12 (cobalamin) is unique among vitamins as it contains the metal ion cobalt in its structure. Vitamin K, not Vitamin A, is essential for the synthesis of blood clotting factors. Vitamin A is crucial for vision and immunity. Thus, statements 1 and 2 are correct.
Explanation:
Molecular oxygen (O₂) accepts electrons at the end of the electron transport chain, combining with protons to form water (metabolic water). Without oxygen, the chain backs up, stopping ATP production. This is why oxygen is vital for aerobic respiration. NAD⁺ and FAD are electron carriers, cytochrome c a component.
No comments yet. Be the first to start the discussion!