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

Explanation:
Robert Hooke first observed and coined the term 'cell' in 1665 using cork tissue. Louis Pasteur definitively disproved the theory of spontaneous generation using his swan-neck flask experiment. Alexander Fleming discovered the antibiotic penicillin, not the structure of DNA; that was elucidated by Watson and Crick. Thus, statements 1 and 2 are correct.

Explanation:
During fertilization, when a capacitated sperm penetrates the outer layer of cumulus cells (corona radiata) and makes contact with the glycoprotein layer called the zona pellucida of the secondary oocyte, it triggers the acrosome reaction. The acrosome (a cap-like vesicle over the sperm head) releases hydrolytic enzymes (like acrosin) that digest a path through the zona pellucida, allowing the sperm to reach and fuse with the oocyte's plasma membrane.

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.