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Biology & health MCQ with Answers

20 questionswith explanationsfor RAS, Patwari, VDO and other Rajasthan exams

Questions

Q1

Deficiency of which vitamin causes scurvy?

  1. (1)Vitamin A
  2. (2)Vitamin B12
  3. (3)Vitamin C
  4. (4)Vitamin D

Answer: (3) Vitamin C

Explanation

Scurvy is caused by a lack of vitamin C (ascorbic acid).

Q2

Which cell organelle is known as the 'powerhouse of the cell'?

  1. (1)Ribosome
  2. (2)Golgi body
  3. (3)Mitochondria
  4. (4)Lysosome

Answer: (3) Mitochondria

Explanation

Mitochondria carry out cellular respiration and produce energy in the form of ATP.

Q3

Deficiency of Vitamin C causes which disease?

  1. (1)Scurvy
  2. (2)Rickets
  3. (3)Beriberi
  4. (4)Night blindness

Answer: (1) Scurvy

Explanation

Lack of Vitamin C (ascorbic acid) causes scurvy, marked by bleeding gums.

Q4

Which blood group is known as the universal donor?

  1. (1)AB
  2. (2)A
  3. (3)B
  4. (4)O

Answer: (4) O

Explanation

Group O red cells have no A or B antigens, so O (especially O negative) is called the universal donor.

Q5

Which is the largest gland in the human body?

  1. (1)Pancreas
  2. (2)Liver
  3. (3)Thyroid
  4. (4)Pituitary

Answer: (2) Liver

Explanation

The liver is the largest gland of the human body; it secretes bile.

Q6

What is the normal body temperature of a healthy human?

  1. (1)35°C
  2. (2)40°C
  3. (3)37°C (98.6°F)
  4. (4)32°C

Answer: (3) 37°C (98.6°F)

Explanation

Normal human body temperature is about 37°C, i.e. 98.6°F.

Q7

The hormone insulin is secreted by which organ?

  1. (1)Pancreas
  2. (2)Liver
  3. (3)Thyroid gland
  4. (4)Adrenal gland

Answer: (1) Pancreas

Explanation

Insulin is secreted by beta cells of the islets of Langerhans in the pancreas and lowers blood sugar.

Q8

How many chromosomes are present in a normal human body (somatic) cell?

  1. (1)23
  2. (2)46
  3. (3)44
  4. (4)48

Answer: (2) 46

Explanation

Human somatic cells have 46 chromosomes (23 pairs); gametes have 23.

Q9

Malaria is caused by which organism?

  1. (1)A virus
  2. (2)A bacterium
  3. (3)A fungus
  4. (4)Plasmodium, a protozoan

Answer: (4) Plasmodium, a protozoan

Explanation

Malaria is caused by the protozoan Plasmodium and spread by the bite of the female Anopheles mosquito.

Q10

Which vitamin is synthesised in human skin in the presence of sunlight?

  1. (1)Vitamin A
  2. (2)Vitamin K
  3. (3)Vitamin D
  4. (4)Vitamin B₁₂

Answer: (3) Vitamin D

Explanation

Ultraviolet rays of sunlight help the skin synthesise Vitamin D, which is needed for healthy bones.

Q11

What is the structural and functional unit of the kidney?

  1. (1)Nephron
  2. (2)Neuron
  3. (3)Alveolus
  4. (4)Villus

Answer: (1) Nephron

Explanation

The nephron filters blood and forms urine; each kidney has about a million nephrons.

Q12

The BCG vaccine is given to protect against which disease?

  1. (1)Polio
  2. (2)Measles
  3. (3)Diphtheria
  4. (4)Tuberculosis

Answer: (4) Tuberculosis

Explanation

BCG (Bacillus Calmette–Guérin) vaccine protects against tuberculosis and is given to newborns in India.

Q13

Which is the smallest bone in the human body?

  1. (1)Femur
  2. (2)Stapes
  3. (3)Radius
  4. (4)Patella

Answer: (2) Stapes

Explanation

The stapes, in the middle ear, is the smallest bone; the femur (thigh bone) is the longest.

Q14

Which cell organelle is the site of protein synthesis?

  1. (1)Golgi apparatus
  2. (2)Lysosome
  3. (3)Ribosome
  4. (4)Centrosome

Answer: (3) Ribosome

Explanation

Ribosomes translate mRNA into proteins, so they are the site of protein synthesis.

Q15

Consider the following statements: 1. The cell wall of plant cells is mainly made of cellulose. 2. Centrioles are generally absent in the cells of higher plants. 3. Lysosomes are known as the 'suicide bags' of the cell. Which of the statements given above is/are correct?

  1. (1)1 and 2 only
  2. (2)2 and 3 only
  3. (3)1 and 3 only
  4. (4)1, 2 and 3

Answer: (4) 1, 2 and 3

Explanation

All three are correct: plant cell walls are cellulosic, higher plant cells lack centrioles, and lysosomes' digestive enzymes earn them the name 'suicide bags'.

Q16

Which type of tissue connects a skeletal muscle to a bone?

  1. (1)Tendon
  2. (2)Ligament
  3. (3)Cartilage
  4. (4)Areolar tissue

Answer: (1) Tendon

Explanation

Tendons join muscles to bones, while ligaments join one bone to another.

Q17

Which enzyme present in gastric juice begins the digestion of proteins in the stomach?

  1. (1)Trypsin
  2. (2)Ptyalin
  3. (3)Lipase
  4. (4)Pepsin

Answer: (4) Pepsin

Explanation

Pepsin, activated by hydrochloric acid in the stomach, starts protein digestion; trypsin acts later in the small intestine.

Q18

Consider the following statements about bile: 1. Bile is produced by the gall bladder. 2. Bile contains no digestive enzyme but helps in the emulsification of fats. Which of the statements given above is/are correct?

  1. (1)1 only
  2. (2)2 only
  3. (3)Both 1 and 2
  4. (4)Neither 1 nor 2

Answer: (2) 2 only

Explanation

Bile is produced by the liver and only stored in the gall bladder; it has no enzymes but its salts emulsify fats.

Q19

Which structure is known as the natural 'pacemaker' of the human heart?

  1. (1)Atrioventricular (AV) node
  2. (2)Sinoatrial (SA) node
  3. (3)Bundle of His
  4. (4)Purkinje fibres

Answer: (2) Sinoatrial (SA) node

Explanation

The SA node in the right atrium generates the impulses that set the rhythm of the heartbeat.

Q20

Which blood vessel carries oxygenated blood from the lungs to the heart?

  1. (1)Pulmonary artery
  2. (2)Vena cava
  3. (3)Pulmonary vein
  4. (4)Aorta

Answer: (3) Pulmonary vein

Explanation

The pulmonary vein is the vein that carries oxygenated blood, from the lungs to the left atrium.