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NEET Biology and Human Welfare MCQs with answers

262 questions on Biology and Human Welfare for NEET 2027. Below are 15 to try; tap a question to see its answer and explanation.

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15 sample questions

easy

1. Dry, scaly lesions on skin, nails, and scalp accompanied by intense itching are characteristic symptoms of ringworm. Which of the following genera of fungi is NOT responsible for this infection?

  1. Aspergillus
  2. Trichophyton
  3. Epidermophyton
  4. Microsporum
Show answer and explanation

Answer: (A) Aspergillus

Ringworm infections in humans are caused by fungi belonging to the genera Microsporum, Trichophyton, and Epidermophyton. Aspergillus is a common mould causing aspergillosis, not ringworms.

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2. Elephantiasis (filariasis) is caused by:

  1. Wuchereria bancrofti and W. malayi
  2. Entamoeba histolytica
  3. Trichophyton
  4. Ascaris
Show answer and explanation

Answer: (A) Wuchereria bancrofti and W. malayi

The filarial worms Wuchereria bancrofti and W. malayi cause chronic inflammation of the organs in which they live, often the lymphatic vessels of the lower limbs. They are transmitted by female mosquitoes.

NCERT Class 12

hard

3. Statins produced by the yeast Monascus purpureus are used as blood-cholesterol-lowering agents because they:

  1. Competitively inhibit the enzyme responsible for synthesis of cholesterol
  2. Dissolve cholesterol in blood vessels
  3. Increase cholesterol excretion through urine
  4. Destroy liver cells that make cholesterol
Show answer and explanation

Answer: (A) Competitively inhibit the enzyme responsible for synthesis of cholesterol

Statins act by competitively inhibiting the enzyme that catalyses cholesterol synthesis.

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4. Normal cells show a property in which contact with other cells inhibits their uncontrolled growth. Cancer cells have lost this property, called:

  1. Differentiation
  2. Metastasis
  3. Apoptosis
  4. Contact inhibition
Show answer and explanation

Answer: (D) Contact inhibition

Cancer cells lose contact inhibition and keep dividing, forming masses called tumours.

easy

5. Given below are two statements: Statement I: Interferons are cytokine barriers of innate immunity secreted by virus-infected cells to protect non-infected cells. Statement II: Humoral immune response is primarily mediated by cytotoxic T-lymphocytes circulating in blood and lymph. In the light of the above statements, choose the most appropriate answer from the options given below:

  1. Both Statement I and Statement II are correct
  2. Statement I is correct but Statement II is incorrect
  3. Statement I is incorrect but Statement II is correct
  4. Both Statement I and Statement II are incorrect
Show answer and explanation

Answer: (B) Statement I is correct but Statement II is incorrect

Statement I is correct as virus-infected cells produce cytokine barriers called interferons, which inhibit viral replication in uninfected cells. Statement II is incorrect because the humoral immune response is mediated by antibodies produced by B-lymphocytes; cell-mediated immunity is mediated by T-lymphocytes.

hard

6. Assertion (A): Curd has better nutritional quality than milk. Reason (R): Lactic acid bacteria in curd increase the vitamin B12 content. Choose the correct option.

  1. Both A and R are true and R is the correct explanation of A
  2. Both A and R are true but R is not the correct explanation of A
  3. A is true but R is false
  4. A is false but R is true
Show answer and explanation

Answer: (A) Both A and R are true and R is the correct explanation of A

LAB improve milk's nutritional quality by increasing vitamin B12, so R explains A.

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7. An antibody molecule is represented as H2L2 because it has:

  1. Two hydrogen and two lysine residues
  2. Two heads and two legs
  3. Two heavy and two light peptide chains
  4. Two haem groups and two lipids
Show answer and explanation

Answer: (C) Two heavy and two light peptide chains

Each antibody molecule has four peptide chains: two small light chains and two longer heavy chains. Different antibodies include IgA, IgM, IgE and IgG.

NCERT Class 12

medium

8. Given below are two statements, one is labelled as Assertion (A) and the other is labelled as Reason (R): Assertion (A): After the entry of HIV into human helper T-cells (T_H), the number of CD4+ T-lymphocytes progressively decreases. Reason (R): HIV utilizes host cellular machinery to replicate, producing new virions that lyse the host T_H cells to release progeny viruses. In the light of the above statements, choose the correct answer from the options given below:

  1. Both (A) and (R) are true and (R) is the correct explanation of (A)
  2. Both (A) and (R) are true but (R) is not the correct explanation of (A)
  3. (A) is true but (R) is false
  4. (A) is false but (R) is true
Show answer and explanation

Answer: (A) Both (A) and (R) are true and (R) is the correct explanation of (A)

HIV attacks helper T-lymphocytes (CD4+), replicates inside them using reverse transcriptase, and releases progeny viruses that infect other T_H cells. This recurrent destruction progressively reduces the T_H cell count, leading to a profound deficiency of the immune system.

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9. The Ganga Action Plan and Yamuna Action Plan were initiated by the:

  1. Indian Council of Medical Research
  2. Ministry of Agriculture
  3. Ministry of Environment and Forests
  4. Department of Biotechnology
Show answer and explanation

Answer: (C) Ministry of Environment and Forests

The Ministry of Environment and Forests initiated these plans to save these rivers from pollution, including building many sewage treatment plants.

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10. The puffed-up appearance of dough used for idli and dosa is due to:

  1. Lactic acid alone
  2. Production of CO2 gas by bacterial fermentation
  3. Air whipped into it
  4. Steam only
Show answer and explanation

Answer: (B) Production of CO2 gas by bacterial fermentation

The dough for idli and dosa is fermented by bacteria. The puffed-up appearance is due to production of CO2 gas.

NCERT Class 12

medium

11. Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Methanogens are present in the anaerobic sludge digesters during sewage treatment as well as in the rumen of cattle. Reason (R): These bacteria grow anaerobically on cellulosic material and break it down, producing large amounts of methane, carbon dioxide, and hydrogen. In the light of the above statements, choose the most appropriate answer:

  1. Both (A) and (R) are true and (R) is the correct explanation of (A)
  2. Both (A) and (R) are true but (R) is not the correct explanation of (A)
  3. (A) is true but (R) is false
  4. (A) is false but (R) is true
Show answer and explanation

Answer: (A) Both (A) and (R) are true and (R) is the correct explanation of (A)

Methanobacterium and related methanogens thrive in anaerobic environments rich in cellulose, such as the rumen of cattle and the anaerobic sludge digesters of STPs. In both environments, they catabolise cellulosic material anaerobically to produce biogas (CH₄, CO₂, and H₂).

medium

12. Ascariasis is caused by the common round worm Ascaris. Its symptoms include:

  1. Internal bleeding, muscular pain, fever, anaemia and blockage of the intestinal passage
  2. Swelling of lower limbs
  3. Dry scaly skin lesions
  4. High fever recurring every three days
Show answer and explanation

Answer: (A) Internal bleeding, muscular pain, fever, anaemia and blockage of the intestinal passage

Ascaris is an intestinal parasite; eggs excreted with faeces contaminate soil, water and plants, and infection occurs through contaminated food and water.

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13. Which pair of organisms are widely employed as biocontrol agents against aphids and mosquitoes, respectively?

  1. Ladybird and Dragonflies
  2. Dragonflies and Ladybird
  3. Trichoderma and Baculovirus
  4. Bacillus thuringiensis and Glomus
Show answer and explanation

Answer: (A) Ladybird and Dragonflies

The Ladybird beetle with red and black markings is used to get rid of aphids, whereas dragonflies are used to control mosquitoes.

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14. BOD (biochemical oxygen demand) refers to:

  1. Oxygen needed by fish
  2. The amount of oxygen that would be consumed if all the organic matter in one litre of water were oxidised by bacteria
  3. Oxygen produced by algae
  4. Oxygen dissolved in pure water
Show answer and explanation

Answer: (B) The amount of oxygen that would be consumed if all the organic matter in one litre of water were oxidised by bacteria

BOD measures the organic matter present in water. The greater the BOD of waste water, the more is its polluting potential. Secondary treatment reduces BOD significantly.

NCERT Class 12

medium

15. Antibiotics are chemical substances that:

  1. Are produced only by humans
  2. Act as vaccines
  3. Increase growth of pathogens
  4. Are produced by some microbes and can kill or retard the growth of other disease-causing microbes
Show answer and explanation

Answer: (D) Are produced by some microbes and can kill or retard the growth of other disease-causing microbes

Antibiotics are produced by some microbes and kill or retard the growth of other microbes. They have greatly reduced deaths from diseases like plague, whooping cough, diphtheria and leprosy.

NCERT Class 12

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