Consider statements about human skin: 1. The epidermis is the outermost layer. 2. Sweat glands help in thermoregulation. 3. Melanin protects against UV radiation. Which are correct? MCQ with Answer and Explanation

Explanation:
Prophase I of meiosis is divided into five sub-stages: leptotene, zygotene, pachytene, diplotene, and diakinesis. Crossing over, the exchange of genetic material between non-sister chromatids of homologous chromosomes, occurs specifically during the pachytene stage at structures called recombination nodules.

Explanation:
DNA polymerase catalyzes the formation of phosphodiester bonds between adjacent nucleotides, extending the new strand complementary to the template. Helicase unwinds DNA, ligase joins fragments, primase synthesizes RNA primer. In prokaryotes, DNA polymerase III is the main replicative enzyme.

Explanation:
Vitamin A (retinol) is essential for the synthesis of rhodopsin (visual pigment in rod cells) and maintenance of epithelial tissues. Deficiency causes night blindness (nyctalopia), xerophthalmia, and ultimately permanent blindness. Bone development is related to vitamin D and calcium. Blood clotting is vitamin K, energy metabolism involves B vitamins. Thus, vision is primarily affected.