RRB Group D Science Top 25 MCQs | By Muskan Ma'am

Biology is a high-scoring section in Railway and other competitive examinations, especially questions related to human physiology, vitamins, diseases, and cell biology. Concept-based MCQs are frequently asked, and understanding the reasoning behind each option is crucial for accuracy.

This set of 25 carefully selected MCQs covers important topics such as endocrine glands, blood groups, deficiency diseases, respiratory disorders, and fundamental cell concepts. Each question includes the correct answer along with explanations of other options to ensure complete conceptual clarity

RRB Group D Science Top MCQs

This section provides a focused review of the top Biology Multiple Choice Questions, critical for candidates preparing for the RRB Group D examination.

1. Which disease is caused by a protozoan parasite?

A. Tuberculosis
B. Malaria
C. Typhoid
D. Cholera

Correct Answer: B. Malaria

Explanation

Only Malaria is caused by a protozoan parasite.

2. Which vitamin helps in blood clotting?

A. Vitamin A
B. Vitamin D
C. Vitamin K
D. Vitamin C

Correct Answer: C. Vitamin K

• Vitamin K (Phylloquinone) helps in blood clot formation.
  
  

• It is essential for clotting factors in blood.

3. Pacemaker of the heart is:

A. AV Node
B. SA Node
C. Purkinje Fibres
D. Ventricles

Correct Answer: B. SA Node

• SA Node (present in right atrium) generates electrical impulses.
  
  

• It controls contraction and relaxation timing of the heart.
  
  

• That is why it is called the pacemaker of the heart.

4. Powerhouse of the cell is:

A. Nucleus
B. Ribosome
C. Mitochondria
D. Golgi Apparatus

Correct Answer: C. Mitochondria

• Mitochondria have double membranes.
  
  

• Inner membrane forms cristae.
  
  

• It produces energy (ATP).

5. Excess secretion of thyroxine causes:

A. Cretinism
B. Myxedema
C. Goitre
D. Exophthalmic Goitre

Correct Answer: D. Exophthalmic Goitre

• Thyroxine controls basal metabolism.
  
  

• Excess thyroxine leads to Exophthalmic Goitre.
  
  

• Cretinism occurs due to deficiency (especially in children).
  
  

• Goitre is linked with iodine deficiency.

6. Deficiency of which vitamin causes night blindness?

A. Vitamin A
B. Vitamin B1
C. Vitamin C
D. Vitamin D

Correct Answer: A. Vitamin A (Retinol)

• Night blindness (Rataundhi) occurs due to Vitamin A deficiency.

7. RBCs are formed in:

A. Liver
B. Kidney
C. Bone Marrow
D. Spleen

Correct Answer: C. Bone Marrow

• All blood cells (RBC, WBC, Platelets) are formed in bone marrow (Asthi Majja).

8. Which disease is transmitted by the female Anopheles mosquito?

A. Dengue
B. Malaria
C. Chikungunya
D. Yellow Fever

Correct Answer: B. Malaria

9. The Fluid Mosaic Model is related to:

A. Cell Wall
B. Plasma Membrane
C. Nucleus
D. Cytoplasm

Correct Answer: B. Plasma Membrane

• Given by Singer and Nicolson.
  
  

• Also called Sandwich Model.
  
  

• Plasma membrane has bilipid layer with proteins embedded.

10. Fight or Flight hormone is:

A. Insulin
B. Thyroxine
C. Adrenaline
D. Growth Hormone

Correct Answer: C. Adrenaline

• Called Emergency Hormone.
  
  

• Secreted by Adrenal Gland.
  
  

• Works in emergency situations (flood, fear, danger).

11. Which vitamin is synthesized in sunlight?

A. Vitamin A
B. Vitamin B
C. Vitamin C
D. Vitamin D

Correct Answer: D. Vitamin D

• Synthesized in skin in presence of sunlight.

12. Universal Blood Donor is:

A. A+
B. B+
C. O–
D. AB+

Correct Answer: C. O–

• Universal Donor → O Negative
  
  

• Universal Recipient → AB Positive

13. Iodine deficiency causes:

A. Anaemia
B. Goitre
C. Rickets
D. Scurvy

Correct Answer: B. Goitre

• Iodine deficiency leads to enlargement of thyroid gland (Goitre).

14. Function of Ribosomes:

A. Respiration
B. Protein synthesis
C. Fat synthesis
D. Cell division

Correct Answer: B. Protein Synthesis

• Ribosomes are called Protein Factory of the cell.

15. Master Gland is:

A. Thyroid
B. Adrenal
C. Pituitary
D. Pancreas

Correct Answer: C. Pituitary

• Controls other endocrine glands.

16. Which disease affects alveoli?

A. Asthma
B. Bronchitis
C. Pneumonia
D. Tuberculosis

Correct Answer: C. Pneumonia

17. Vitamin C deficiency causes:

A. Beriberi
B. Scurvy
C. Rickets
D. Pellagra

Correct Answer: B. Scurvy

18. Organelle that modifies and packages protein:

A. ER
B. Lysosome
C. Golgi Apparatus
D. Ribosome

Correct Answer: C. Golgi Apparatus

• Modifies and packages proteins.
  
  

• Called Post Office of the cell.

19. Diabetes Mellitus is caused due to deficiency of:

A. Adrenaline
B. Insulin
C. Glucagon
D. Thyroxine

Correct Answer: B. Insulin

• Insulin lowers blood sugar.
  
  

• Glucagon increases blood sugar.

20. Lockjaw disease is:

A. Diphtheria
B. Tetanus
C. Rabies
D. Polio

Correct Answer: B. Tetanus

• A bacterial disease.
  
  

• Affects nervous system.
  
  

• Jaw muscles become stiff

21. Vitamin B1 deficiency causes:

A. Beriberi
B. Anaemia
C. Rickets
D. Night Blindness

Correct Answer: A. Beriberi

• Anaemia → Iron deficiency
  
  

22. Oxygenated blood is pumped from:

A. Right Atrium
B. Right Ventricle
C. Left Atrium
D. Left Ventricle

Correct Answer: D. Left Ventricle

• Left ventricle pumps oxygenated blood to body via aorta.

23. Cell Theory was given by:

A. Robert Hooke
B. Schleiden & Schwann
C. Darwin
D. Mendel

Correct Answer: B. Schleiden & Schwann

• All living organisms are made up of cells.

24. HIV causes:

A. Cancer
B. AIDS
C. Hepatitis
D. Tuberculosis

Correct Answer: B. AIDS

• AIDS = Acquired Immuno Deficiency Syndrome
  
  

• HIV weakens immunity.
  
  

• World AIDS Day → 1 December
  
  

• Test → ELISA

25. Blood vessel carrying blood away from heart:

A. Vein
B. Capillary
C. Artery
D. Venule

Correct Answer: C. Artery

• Arteries carry blood away from heart.

Strong fundamentals in Biology can significantly improve overall exam scores. Regular practice of MCQs, along with understanding why other options are incorrect, helps avoid confusion in the exam hall.

Revising these 25 important questions will strengthen your grasp on frequently asked topics and enhance your confidence for upcoming competitive exams. Consistent practice and conceptual clarity remain the key to scoring well in Biology.