NEET Biology Microbes in Human Welfare MCQs Set 17

Answer: (c) Bio-insecticidal plants

Explanation:
1. Genes of Bacillus thuringiensis toxin are transferred into plants such as cotton to make bio-insecticidal (pest-resistant) plants.
2. Hence option (c) is correct: Bio-insecticidal plants

Teacher's Note:
1. Genes for the Bt toxin are put into crops to make them insect resistant.
2. Bt cotton and Bt maize are examples.

Answer: (d) CH₄ + CO₂

Explanation:
1. Gobar gas → CH₄ + CO₂+ ...
2. Hence option (d) is correct: CH₄ + CO₂

Teacher's Note:
1. Gobar gas is a mixture of methane and carbon dioxide with traces of other gases.
2. Methane is the fuel part.

Answer: (a) Cactus

Explanation:
1. Cochineal insect (Cactoblastic cactorum) have proved very useful for the control of cactus.
2. Hence option (a) is correct: Cactus

Teacher's Note:
1. The cochineal insect Cactoblastis cactorum eats prickly pear cactus.
2. It was used to control the cactus in Australia.

Answer: (c) Biological control

Explanation:
1. Using a living organism such as a predator or pathogen to control a pest is biological control.
2. Hence option (c) is correct: Biological control

Teacher's Note:
1. Using a natural predator or parasite against a pest is biological control.
2. It reduces chemical pesticide use.

Answer: (c) Azolla

Explanation:
1. Azolla is natural biofertilizers.
2. Hence option (c) is correct: Azolla

Teacher's Note:
1. Azolla is a water fern with the cyanobacterium Anabaena in its leaf cavities.
2. It is an excellent biofertiliser for rice fields.

Answer: (c) Anabaena

Explanation:
1. Anabaena, a nitrogen-fixing cyanobacterium, enriches paddy soil with nitrogen and so increases the yield of rice.
2. Hence option (c) is correct: Anabaena

Teacher's Note:
1. Anabaena is a nitrogen-fixing cyanobacterium that enriches paddy fields.
2. This raises the yield of rice.

Answer: (a) Anabaena and Azolla

Explanation:
1. Biofertilizers are Anabaena and Azolla
2. Hence option (a) is correct: Anabaena and Azolla

Teacher's Note:
1. Biofertilisers are living organisms that raise soil nutrients, such as Anabaena and Azolla.
2. Cow dung and green manure are manures, not biofertilisers.

Answer: (b) Both Assertion and Reason are true but the Reason is not a correct explanation of the Assertion.

Explanation:
1. Curd is more nutritious than milk, in curd LAB is found that checks growth of disease causing microbes in our stomach.
2. Hence option (b) is correct: Both Assertion and Reason are true but the Reason is not a correct explanation of the Assertion.

Teacher's Note:
1. Curd is richer than milk in vitamin B12 and LAB check harmful microbes.
2. The reason given does not explain why curd is more nutritious.

Answer: (a) Both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.

Explanation:
1. After 24 hours toddy becomes unpalatable because toddy left over a few hours undergoes fermentation.
2. Hence option (a) is correct: Both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.

Teacher's Note:
1. Toddy ferments within a few hours and becomes unpalatable after 24 hours.
2. The reason explains the assertion.

Answer: (a) Both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.

Explanation:
1. Pathogens often develop resistance to existing antibiotics so newer antibiotics are required to be produced regularly.
2. Hence option (a) is correct: Both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.

Teacher's Note:
1. Pathogens develop resistance to antibiotics over time.
2. Therefore new antibiotics are needed.

Answer: (c) Assertion is true but the Reason is false.

Explanation:
1. Cyclosporin A is an immunosuppressive medicine, it prevents organ rejection.
2. Hence option (c) is correct: Assertion is true but the Reason is false.

Teacher's Note:
1. Cyclosporin A suppresses the immune system, so it prevents rejection of transplants.
2. It does not stimulate T-cells.

Answer: (c) Assertion is true but the Reason is false.

Explanation:
1. Barley, Sorghum and millet are smoother crops. They retard the growth of weeds.
2. Hence option (c) is correct: Assertion is true but the Reason is false.

Teacher's Note:
1. Smother crops like barley, sorghum and millet retard weed growth.
2. The reason is wrong because they do not favour weeds.

Answer: (c) Assertion is true but the Reason is false.

Explanation:
1. Baculovirus are species specific. It is a parasite of insects and other arthropods.
2. Hence option (c) is correct: Assertion is true but the Reason is false.

Teacher's Note:
1. Baculoviruses are species specific and parasitise insects and other arthropods.
2. They are not effective against plant pathogens, so the reason is false.

Answer: (b) Both Assertion and Reason are true but the Reason is not a correct explanation of the Assertion.

Explanation:
1. Statins are produced by fermentation activity of yeast. Both statins and mevalonate compete for same active site on enzyme that is involved in cholesterol synthesis.
2. Hence option (b) is correct: Both Assertion and Reason are true but the Reason is not a correct explanation of the Assertion.

Teacher's Note:
1. Statins come from Monascus (yeast) fermentation and compete with the substrate of the enzyme for cholesterol synthesis.
2. The mode of action does not explain how statins are produced.

Answer: (d) Both Assertion and Reason are false.

Explanation:
1. Wine and beer are produced without distilation of fermented broth, so they have low concentration of alcohols. Alcoholic drinks obtained by fermentation and followed by with or without distilation process.
2. Hence option (d) is correct: Both Assertion and Reason are false.

Teacher's Note:
1. Wine and beer are made by fermentation without distillation.
2. Whisky and brandy are produced by distillation, so both statements are false.

Answer: (c) Assertion is true but the Reason is false.

Explanation:
1. The chief component of biogas is methane i.e., 50% - 70%. Biogas plants are prepared on the Indian technology.   
2. Hence option (c) is correct: Assertion is true but the Reason is false.

Teacher's Note:
1. The main component of biogas is methane (50 to 70 percent).
2. Biogas technology developed in India, so the reason is false.