Free Microbes In Human Welfare (Daily Quiz: 16) NEET Biology Questions & Answers with Detailed Explanation & Full Review

Answer: (b)

The Bt toxin is an inactive protoxin, which gets activated due to the alkaline pH of the insect gut. Proteins are solubilised and proteolytically processed when exposed to alkaline pH and thus are activated. The toxins then attack the gut cells of the insect, creating holes in the lining casusing lysis and death of the insect.

Answer: (d)

Cheese is a protein rich nutritive preparation obtained after fermentation and curdling of milk. Cheese contains proteins (20-35%), fats (20-30%), minerals, vitamins and water. Milk is first curdled (soured) with the help of a lactic acid bacterium. Curd is gently heated to separate cheese from liquid called whey. Curd is placed in cloth-lined porous containers for draining out whey. The left out solidified material is called cottage cheese. For preservation and ripening, blocks of cottage cheese are salted and placed in brine solution. Salt solution is drained out. Cheese blocks are wiped and placed in sterilised rooms for ripening with the help of microorganisms.

Answer: (d)

Activated sludge is a mass of microorganisms cultivated in the treatment process to break down organic matter into carbon dioxide, water, and other inorganic compounds. The activated sludge process has three basic components: i) a reactor in which the microorganisms are kept in suspension, aerated, and in contact with the waste they are treating; ii. liquid-solid separation and iii. a sludge recycling system for returning activated sludge back to the beginning of the process.

Answer: (d)

Bioremediation is the process of using living microorganisms to clean up a contaminated site. Microorganisms do this by removing toxins from materials. They decompose these compounds by using enzymes, specific proteins that control reactions in living cells. Organisms that produce enzymes capable of degrading petroleum are useful in cleaning up oil spills. Some common ones that break down oil are genetically engineered species of Pseudomonas and Azotobacter. Bioremediation accounts for 5 to 10 percent of all pollution treatment and has been used successfully in cleaning up leaking underground gasoline storage tanks. Bioremediation has many applications, from the ordinary garden compost to the removal of selenium and other toxic metals from waste. The best agents for bioremediation are the ones that can break down contaminants without becoming contaminated or harmful themselves.