NEET 2025 MCQ with Answer Explanation : Microbes in Human Walefare.

41. A microbial product that is used to suppress the immune system during organ transplants is:
    A. Penicillin
    B. Streptomycin
    C. Cyclosporin A
    D. Ethanol

Answer: C. Cyclosporin A

Explanation:
Cyclosporin A is an immunosuppressive agent produced by the fungus Trichoderma polysporum, used to prevent organ rejection after transplants.

42. The microorganisms used to treat waste in septic tanks are primarily:
    A. Viruses
    B. Fungi
    C. Bacteria
    D. Algae

Answer: C. Bacteria

Explanation:
Septic tanks rely on bacteria to break down solid waste through anaerobic digestion, converting it into simpler substances.

43. Bacillus thuringiensis is used in agricultural fields as:
    A. Bioinsecticide
    B. Biofertilizer
    C. Antibiotic
    D. Bioherbicide

Answer: A. Bioinsecticide

Explanation:
Bacillus thuringiensis (Bt) produces a toxin that kills insect larvae, making it a widely used bioinsecticide in organic and conventional farming.

44. Which of the following produces lactic acid from glucose fermentation?
    A. Streptococcus
    B. Lactobacillus
    C. Rhizobium
    D. Penicillium

Answer: B. Lactobacillus

Explanation:
Lactobacillus bacteria convert glucose into lactic acid, a process that occurs during the production of yogurt and other fermented dairy products.

45. What is the role of Saccharomyces cerevisiae in bread-making?
    A. It converts sugar into acetic acid.
    B. It produces carbon dioxide during fermentation.
    C. It produces ethanol during fermentation.
    D. It decomposes proteins into amino acids.

Answer: B. It produces carbon dioxide during fermentation.

Explanation:
In bread-making, Saccharomyces cerevisiae ferments sugars to produce carbon dioxide, which helps the dough rise and gives bread its light texture.

46. The bacteria Pseudomonas putida is known for its use in:
    A. Antibiotic production
    B. Pollution control
    C. Nitrogen fixation
    D. Dairy fermentation

Answer: B. Pollution control

Explanation:
Pseudomonas putida is used in bioremediation to degrade pollutants such as hydrocarbons and oil spills, making it important in environmental pollution control.

47. The enzyme used to break down starch into simple sugars in industries is produced by:
    A. Aspergillus oryzae
    B. Lactobacillus acidophilus
    C. Rhizopus stolonifer
    D. Penicillium notatum

Answer: A. Aspergillus oryzae

Explanation:
Aspergillus oryzae produces amylase, an enzyme that converts starch into simple sugars, used in brewing, baking, and biofuel production.

48. A soil microorganism that plays a major role in organic matter decomposition is:
    A. Streptomyces
    B. Clostridium
    C. Lactobacillus
    D. Escherichia coli

Answer: A. Streptomyces

Explanation:
Streptomyces bacteria are important decomposers in soil, breaking down complex organic matter into simpler compounds, enriching soil fertility.

49. What is the function of the bacterium Xanthomonas campestris in the food industry?
    A. Production of lactic acid
    B. Production of xanthan gum
    C. Antibiotic production
    D. Biogas production

Answer: B. Production of xanthan gum

Explanation:
Xanthomonas campestris produces xanthan gum, a polysaccharide used as a thickening agent and stabilizer in various food products like salad dressings and sauces.

50. The microorganisms involved in the formation of humus are:
    A. Algae
    B. Fungi and bacteria
    C. Viruses
    D. Protozoa

Answer: B. Fungi and bacteria

Explanation:
Fungi and bacteria are key players in the decomposition of organic matter in soil, leading to the formation of humus, which enhances soil fertility.