The jelly-like substance that fills the cell and holds organelles is the: MCQ with Answer and Explanation

Explanation:
Active vitamin D (calcitriol) induces synthesis of calcium-binding proteins in the intestinal mucosa, enhancing calcium absorption. Calcium is vital for bones, teeth, blood clotting, and nerve-muscle function.

Explanation:
Double circulation (pulmonary and systemic) with a four-chambered heart keeps oxygenated and deoxygenated blood separate, increasing efficiency. R correctly explains A.

Explanation:
The anther is the male reproductive part of the flower where microspores develop into pollen grains. After fertilization, the ovary wall matures and develops into the fruit, enclosing the seeds. Self-pollination involves the transfer of pollen to the stigma of the same flower or plant, resulting in offspring genetically identical to the parent, thus decreasing, not increasing, genetic diversity. Thus, statements 1 and 2 are correct.