Class 12 Biology Practice Questions

Q1. Mendel's law of segregation states that: 🧬

1. Genes are linked to sex chromosomes
2. Alleles separate during gamete formation
3. All offspring are identical
4. Traits blend in offspring

Q2. According to Darwin, natural selection acts on: 🧬

1. Acquired characteristics
2. Heritable variations that affect survival and reproduction
3. Random genetic drift alone
4. Mutations only

Q3. The process of copying DNA into RNA is called: 🧬

1. Transcription
2. Replication
3. Transduction
4. Translation

Q4. Which part of the ecosystem includes all living organisms? 🧬

1. Lithosphere
2. Biotic component
3. Hydrosphere
4. Abiotic component

Q5. The blood group that is considered the universal donor is: 🧬

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

Q6. In a food chain, the organisms that fix solar energy are: 🧬

1. Herbivores
2. Decomposers
3. Producers
4. Consumers

Q7. Down syndrome is caused by trisomy of chromosome number: 🧬

1. 18
2. 21
3. 13
4. 23

Q8. Which enzyme is used to cut DNA at specific sequences in genetic engineering? 🧬

1. Restriction endonuclease
2. Ligase
3. RNA polymerase
4. DNA polymerase

Q9. Biodiversity hotspots are areas with: 🧬

1. Only marine organisms
2. Low species diversity
3. High species diversity and endemism
4. Extreme climatic conditions

Q10. The human genome contains approximately how many genes? 🧬

1. 100,000–150,000
2. 1,000,000+
3. 20,000–25,000
4. 2,000–3,000

Q11. Who is known as the Father of Genetics?

1. Gregor Mendel
2. Charles Darwin
3. Louis Pasteur
4. Robert Hooke

Q12. Which molecule carries hereditary information in most living organisms?

1. RNA
2. DNA
3. Protein
4. Lipid

Q13. Which type of cell division produces gametes (sex cells)?

1. Mitosis
2. Binary fission
3. Meiosis
4. Budding

Q14. Which hormone regulates blood sugar levels in the human body?

1. Adrenaline
2. Thyroxine
3. Oestrogen
4. Insulin

Q15. Which blood cells defend the body against infection?

1. White blood cells
2. Red blood cells
3. Platelets
4. Plasma

Q16. Which of Mendel's laws states that alleles separate during gamete formation?

1. Law of Dominance
2. Law of Segregation
3. Law of Independent Assortment
4. Law of Gravitation

Q17. Which organelle is called the powerhouse of the cell?

1. Nucleus
2. Ribosome
3. Mitochondria
4. Golgi body