Which of the following statements about the circulatory system is correct? MCQ with Answer and Explanation

Explanation:
A human zygote is diploid (2n = 46), formed by the fusion of a haploid sperm (23) and a haploid ovum (23). It contains 22 pairs of autosomes and one pair of sex chromosomes (XX or XY). Mitotic division then produces all somatic cells. Gametes are haploid (23).

Explanation:
The choroid plexus, a network of ependymal cells and capillaries in the ventricles of the brain, continuously produces CSF by filtration and secretion. CSF circulates through ventricles and the subarachnoid space and is reabsorbed by arachnoid villi into the venous system. Dura mater is the outer protective membrane.

Explanation:
Vitamin A (retinol) is crucial for the maintenance of the cornea and the synthesis of rhodopsin, a pigment necessary for vision in dim light. Vitamin C (ascorbic acid) is essential for the synthesis of collagen; its deficiency leads to scurvy, characterized by bleeding gums and poor wound healing. Vitamin K, not Vitamin D, is essential for the synthesis of prothrombin and other clotting factors. Vitamin D is essential for calcium absorption and bone health. Thus, statements 1 and 2 are correct.