IJMB Biology
Past Questions

19+ verified Biology past questions for IJMB. Step-by-step worked answers in 5 Nigerian languages.

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Biology topics (2)

Genetics
2 questions
Cell Biology
0 questions

Sample Biology past questions

1. Human female sex chromosomes.

  • A. XY
  • B. XX
  • C. YY
  • D. XO

Answer: B

AI Explanation

**The reasoning** In humans, biological sex is determined by a pair of chromosomes called sex chromosomes. Females have **two X chromosomes (XX)**, while males have one X and one Y chromosome (XY). This is basic genetics — you inherit one sex chromosome from each parent. A mother (XX) can only give an X, while a father (XY) can give either X or Y. If you get X from both parents, you develop as female (XX). **Why the wrong options tempt you** - **A) XY** — This is the *male* combination. Easy to mix up if you're rushing or didn't memorize which is which. - **C) YY** — Biologically impossible in humans! You *must* get at least one X chromosome to survive. YY can't exist naturally. - **D) XO** — This is actually a chromosomal disorder called Turner syndrome (only one X, no second sex chromosome). It's not the normal female pattern. **Quick takeaway** Remember: **"XX = eXtra X = female"** — two X's make a girl, just like you need two to make a pair!

2. Number of human chromosomes (somatic).

  • A. 23
  • B. 44
  • C. 46
  • D. 48

Answer: C

3. The human heart has how many chambers?

  • A. 2
  • B. 3
  • C. 4
  • D. 5

Answer: C

4. Chlorophyll absorbs mainly which light?

  • A. Green
  • B. Red and blue
  • C. Yellow
  • D. All equally

Answer: B

5. The basic unit of classification is the:

  • A. Genus
  • B. Species
  • C. Family
  • D. Order

Answer: B

6. Red blood cells carry oxygen using:

  • A. Insulin
  • B. Haemoglobin
  • C. Plasma
  • D. Platelets

Answer: B

7. Pollination is the transfer of pollen to the:

  • A. Root
  • B. Stigma
  • C. Leaf
  • D. Stem

Answer: B

8. The functional unit of the nervous system is the:

  • A. nephron
  • B. neuron
  • C. alveolus
  • D. axon

Answer: B

AI Explanation

Neuron — specialised cell that transmits nerve impulses.

9. Photosynthesis takes place in the:

  • A. mitochondria
  • B. chloroplast
  • C. nucleus
  • D. ribosome

Answer: B

AI Explanation

Chloroplasts contain chlorophyll for converting light energy to chemical energy.

10. Which gas is released by plants during photosynthesis?

  • A. nitrogen
  • B. carbon dioxide
  • C. oxygen
  • D. hydrogen

Answer: C

AI Explanation

Plants take in CO₂ and release O₂.

11. The largest organ in the human body is the:

  • A. heart
  • B. skin
  • C. liver
  • D. brain

Answer: B

AI Explanation

Skin is the largest organ — about 2 m² in adults.

12. DNA stands for:

  • A. Deoxyribonucleic acid
  • B. Diribonucleic acid
  • C. Direct nucleic acid
  • D. Double nucleic acid

Answer: A

AI Explanation

DNA = Deoxyribonucleic Acid.

13. The site of protein synthesis in a cell is the:

  • A. lysosome
  • B. ribosome
  • C. vacuole
  • D. Golgi

Answer: B

AI Explanation

Ribosomes assemble amino acids into proteins.

14. Mitosis produces:

  • A. four haploid cells
  • B. two identical diploid cells
  • C. one large cell
  • D. gametes only

Answer: B

AI Explanation

Mitosis: one parent cell → two genetically identical daughter cells.

15. Meiosis is associated with:

  • A. growth
  • B. tissue repair
  • C. production of gametes
  • D. respiration

Answer: C

AI Explanation

Meiosis halves the chromosome number to make eggs/sperm (gametes).

16. Which blood cells fight infection?

  • A. red blood cells
  • B. white blood cells
  • C. platelets
  • D. plasma

Answer: B

AI Explanation

Leucocytes (white blood cells) are the immune defenders.

17. An ecosystem includes:

  • A. only animals
  • B. only plants
  • C. living organisms and their physical environment
  • D. only microbes

Answer: C

AI Explanation

Ecosystem = biotic + abiotic components interacting.

18. Producers in an ecosystem are typically:

  • A. herbivores
  • B. carnivores
  • C. green plants and algae
  • D. decomposers

Answer: C

AI Explanation

Producers (autotrophs) make their own food via photosynthesis.

19. Vitamin C deficiency causes:

  • A. rickets
  • B. scurvy
  • C. anaemia
  • D. night blindness

Answer: B

AI Explanation

Scurvy from lack of vitamin C causes bleeding gums and weakness.

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