Deficiency of which vitamin causes night blindness? MCQ with Answer and Explanation

Explanation:
In prokaryotes, DNA polymerase I has 5'→3' exonuclease activity that removes RNA primers and fills the gaps with DNA. DNA pol III extends strands, ligase joins, primase synthesizes primer.

Explanation:
Filippo Pacini first observed Vibrio cholerae in 1854, but Robert Koch later independently identified it and demonstrated its role. Koch is often credited, but Pacini's discovery was earlier. John Snow linked cholera to water.

Explanation:
Zinc is an essential micronutrient for plants, involved in the synthesis of the auxin indole-3-acetic acid (IAA) via the activation of tryptophan synthetase. Zinc deficiency causes 'little leaf' and 'rosette' diseases, stunted growth, and reduced internodes. Iron is needed for chlorophyll synthesis, manganese for photosynthesis, and boron for pollen germination.