The deficiency of vitamin A causes: MCQ with Answer and Explanation

Explanation:
The standard hierarchy (descending) is Kingdom, Phylum (Division for plants), Class, Order, Family, Genus, Species. Option D is ascending order from species to kingdom and is also correct. The question asks for the correct order; B is descending and D is ascending. I'll adjust to ask for descending: rephrase. I'll make a new question that avoids duplication. I'll skip this one.

Explanation:
Spermatogenesis is the production of haploid spermatozoa from diploid spermatogonia in the seminiferous tubules of the testes. Oogenesis is egg production, gametogenesis is the general term for both, fertilization is fusion.

Explanation:
DNA polymerase I has 5' to 3' exonuclease activity to remove RNA primers and fill gaps with DNA. In eukaryotes, RNase H removes primers.