Which of the following is a biofertilizer commonly used for rice cultivation? MCQ with Answer and Explanation

Explanation:
Denitrification, carried out by bacteria like Pseudomonas, reduces nitrates to N₂ gas, returning it to the atmosphere. Nitrification converts ammonia to nitrates, ammonification releases ammonia, nitrogen fixation converts N₂ to ammonia.

Explanation:
Zymase is the enzyme complex in yeast that catalyzes alcoholic fermentation, converting pyruvate to ethanol and CO₂. Invertase hydrolyzes sucrose, lactase breaks lactose, maltase breaks maltose. Zymase activity is exploited in baking and brewing industries.

Explanation:
The placenta begins to form immediately after implantation of the blastocyst. By the end of the first trimester (around 12 weeks of gestation), the placenta is fully formed and takes over the primary role of hormone production (progesterone and estrogen) from the corpus luteum. It is fully functional in providing oxygen, nutrients, and waste removal for the developing fetus for the remainder of the pregnancy. It is not fully formed at conception, nor does it wait until the second or third trimester.