Biology, Human Body and Health MCQs

Solved biology MCQs on cells, the human body, blood, vitamins and deficiency diseases, infections and vaccines, plants and branches of biology.

1. 1

   Which cell organelle is called the "powerhouse of the cell"?

   ARibosomeBGolgi bodyCMitochondrionDNucleus

   Correct answer: C. Mitochondrion

   Mitochondria release energy from food in the form of ATP during respiration.

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2. 2

   The structural and functional unit of the kidney is the:

   AalveolusBnephronCvillusDneuron

   Correct answer: B. nephron

   Each kidney has about a million nephrons that filter blood and form urine.

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3. 3

   A person with which blood group is called a universal donor?

   AB negativeBA positiveCO negativeDAB positive

   Correct answer: C. O negative

   O negative red cells have no A, B or Rh antigens. AB positive people are universal recipients.

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4. 4

   Which vitamin is essential for blood clotting?

   AVitamin DBVitamin CCVitamin KDVitamin A

   Correct answer: C. Vitamin K

   Vitamin K helps make clotting factors such as prothrombin.

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5. 5

   Night blindness is caused by a deficiency of:

   Avitamin B1Bvitamin DCvitamin ADvitamin C

   Correct answer: C. vitamin A

   Vitamin A is needed for the light-sensitive pigment in the retina.

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6. 6

   Malaria is caused by a:

   AvirusBprotozoan (Plasmodium)CfungusDbacterium

   Correct answer: B. protozoan (Plasmodium)

   Plasmodium parasites are spread by the bite of the female Anopheles mosquito.

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7. 7

   The largest gland in the human body is the:

   ApancreasBpituitaryCthyroidDliver

   Correct answer: D. liver

   The liver is the largest gland; it makes bile and stores glycogen.

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8. 8

   Red blood cells in a healthy adult live for about:

   A20 daysB120 daysC1 yearD60 days

   Correct answer: B. 120 days

   RBCs survive about 120 days and are then broken down, mainly in the spleen and liver.

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9. 9

   Photosynthesis takes place in the:

   AchloroplastsBnucleusCvacuoleDmitochondria

   Correct answer: A. chloroplasts

   Chloroplasts contain chlorophyll, which traps sunlight to make glucose from carbon dioxide and water.

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10. 10

    Diabetes mellitus is linked to a shortage or poor action of:

    AthyroxineBglucagonCadrenalineDinsulin

    Correct answer: D. insulin

    Insulin from the pancreas lets cells take up glucose; without enough of it, blood sugar stays high.

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12. 11

    Haemoglobin contains which metal?

    AIronBZincCCopperDMagnesium

    Correct answer: A. Iron

    Iron in haemoglobin binds oxygen. Magnesium is found in chlorophyll.

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13. 12

    How many chromosomes are there in a normal human body cell?

    A23B44C46D48

    Correct answer: C. 46

    Body cells have 46 chromosomes (23 pairs); sperm and egg cells have 23.

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14. 13

    The BCG vaccine protects against:

    AtuberculosisBpolioCmeaslesDtetanus

    Correct answer: A. tuberculosis

    BCG (Bacillus Calmette–Guérin) is given at birth in India against tuberculosis.

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15. 14

    The smallest bone in the human body is the:

    AstapesBincusCfemurDpatella

    Correct answer: A. stapes

    The stapes, one of the three tiny bones of the middle ear, is the smallest. The femur is the longest.

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16. 15

    The digestion of proteins begins in the:

    AstomachBmouthClarge intestineDsmall intestine

    Correct answer: A. stomach

    The enzyme pepsin starts breaking down proteins in the stomach. Starch digestion starts in the mouth.

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17. 16

    Dengue is spread by the bite of the:

    AhouseflyBAedes mosquitoCCulex mosquitoDAnopheles mosquito

    Correct answer: B. Aedes mosquito

    Aedes aegypti, which bites mostly in the daytime, spreads dengue and chikungunya.

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18. 17

    Goitre is caused by a lack of:

    AironBsodiumCcalciumDiodine

    Correct answer: D. iodine

    Without enough iodine the thyroid gland swells. Iodised salt prevents it.

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19. 18

    Which chamber of the heart pumps blood to the lungs?

    ALeft atriumBLeft ventricleCRight atriumDRight ventricle

    Correct answer: D. Right ventricle

    The right ventricle sends blood to the lungs through the pulmonary artery; the left ventricle pumps blood to the body.

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20. 19

    The study of fungi is called:

    AphycologyBornithologyCmycologyDvirology

    Correct answer: C. mycology

    Mycology is the study of fungi. Phycology studies algae and ornithology birds.

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21. 20

    Plants lose water as vapour mainly through tiny pores on their leaves called:

    Aroot hairsBxylemClenticelsDstomata

    Correct answer: D. stomata

    This loss of water through stomata is called transpiration.

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