Bile juice is secreted by the: MCQ with Answer and Explanation

Explanation:
PCR, invented by Kary Mullis, allows exponential amplification of a specific DNA segment using a thermostable DNA polymerase (Taq polymerase), primers, and thermal cycling. Gel electrophoresis separates DNA fragments, Southern blotting detects specific sequences, DNA sequencing determines the order of bases. PCR is widely used in diagnostics, forensics, and research.

Explanation:
Cyanobacteria (blue-green algae) are photosynthetic, oxygenic prokaryotes that play a crucial role in nitrogen fixation in aquatic and terrestrial ecosystems. Mycorrhiza is a mutualistic symbiotic association between a fungus and the roots of a vascular plant, where the fungus aids in nutrient absorption and the plant provides carbohydrates. Nitrosomonas is a nitrifying bacterium that converts ammonia to nitrite; denitrifying bacteria like Pseudomonas convert nitrates to nitrogen gas. Thus, statements 1 and 2 are correct.

Explanation:
Vitamin A (retinol) is essential for the synthesis of rhodopsin, the visual pigment in rod cells responsible for low-light vision. Deficiency leads to night blindness (nyctalopia) and, if severe, xerophthalmia and permanent blindness. Vitamin B₁ deficiency causes beriberi, C scurvy, D rickets.