Methanobacterium is also present in the _____ of cattle which helps i…

The correct answer is Option (3) → Stomach

Methanobacterium is a methanogen: it grows without oxygen on cellulose and gives out methane. It lives in the rumen, a part of the stomach of cattle, where it helps break down the cellulose of their food. That is why cattle dung is rich in these bacteria and is used in biogas plants.

Option (3) Stomach — Correct. Methanogens like Methanobacterium live in the rumen, a part of the stomach of cattle. There they help break down the cellulose in the cattle’s food and release methane.

NCERT Extract:
Microbes in Production of Biogas – “… However, certain bacteria, which grow anaerobically on cellulosic material, produce large amount of methane along with CO₂ and H₂. These bacteria are collectively called methanogens, and one such common bacterium is Methanobacterium. These bacteria are commonly found in the anaerobic sludge during sewage treatment. These bacteria are also present in the rumen (a part of stomach) of cattle. A lot of cellulosic material present in the food of cattle is also present in the rumen. In rumen, these bacteria help in the breakdown of cellulose and play an important role in the nutrition of cattle.”