NEET Practice Questions (MCQs) with Answers & Solutions

Methane gas is produced by bacteria from the compound cellulase. Cellulase breaks down cellulose, a major component of plant cell walls, into simpler sugars which can be further processed by methanogenic bacteria to produce methane. This process is significant in anaerobic digestion and biogas production.

In anaerobic sludge digesters, multiple gases are produced including CO₂, H₂S, and CH₄. This is because the anaerobic digestion process involves the breakdown of organic matter by bacteria in the absence of oxygen, leading to the production of these gases. Therefore, the correct answer is 'All the given' gases.

Algae are generally not used as biocontrol agents. Biocontrol agents typically include viruses, bacteria, and fungi which can target specific pests or pathogens. Algae do not fit well into this category as they do not have the necessary properties to control pests or pathogens in a targeted manner.

Methanogens are a group of archaea that produce methane as a metabolic byproduct in anoxic conditions. They are commonly found in wetlands, ruminant animals, and are crucial for the production of biogas in anaerobic digesters.

Rhizobium is a genus of bacteria that forms a symbiotic relationship with leguminous plants. It colonizes the root nodules of these plants and fixes atmospheric nitrogen ( ext{N}_2) into a form that the plants can use, such as ammonia ( ext{NH}_3), thus aiding in nitrogen fixation.

Aspergillus niger is a type of fungus that is commonly used in the industrial production of citric acid. This microorganism is optimized for high yield production of citric acid through the process of fermentation, making it a crucial component in various industries, including food and pharmaceuticals.

Cheese and toddy are obtained through the process of fermentation. In cheese production, milk is fermented using specific bacteria to produce lactic acid, which helps coagulate the milk proteins. Toddy, a traditional alcoholic beverage, is made by fermenting the sap of palm trees using natural yeasts.