CBSE Class 12 Biology Sample Paper Set 2 — Free PDF
Complete biology sample paper covering genetics, evolution, ecology, plant and animal physiology. Master concepts related to reproduction, biotechnology, a
TL;DR: Complete biology sample paper covering genetics, evolution, ecology, plant and animal physiology. Master concepts related to reproduction, biotechnolo…
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Complete biology sample paper covering genetics, evolution, ecology, plant and animal physiology. Master concepts related to reproduction, biotechnology, and human welfare. This is a shortened practice set: 26 questions worth 68 marks, following the 70-mark CBSE paper pattern. Use it for timed practice, not as a full-length mock.
Board: CBSE · Class: Class 12 · Subject: Biology · Total: 68 marks · Time: 3 hours
Section A - Objective Type Questions — 7 marks
Attempt all questions. Each question carries 1 mark.
Q1. The basic unit of life is? (1 mark)
Answer: Cell
Q2. DNA stands for? (1 mark)
Answer: Deoxyribonucleic Acid
Q3. The process of formation of new blood cells is called? (1 mark)
Answer: Hematopoiesis
Q4. Immunity conferred by antibodies is? (1 mark)
Answer: Humoral immunity
Q5. The structural and functional unit of kidney is? (1 mark)
Answer: Nephron
Q6. Photosynthetically active region of spectrum is? (1 mark)
Answer: 400-700 nm
Q7. The first hormone isolated was? (1 mark)
Answer: Insulin
Section B - Short Answer Questions — 28 marks
Attempt all questions. Each question carries 2 or 3 marks.
Q1. What is transcription? Explain its types in prokaryotes and eukaryotes. (2 marks)
Answer: Synthesis of RNA from DNA, Prokaryotes: single RNA polymerase, Eukaryotes: three RNA polymerases
Q2. Explain the process of translation and its three stages. (3 marks)
Answer: Protein synthesis from mRNA, Initiation: ribosome assembly, Elongation: amino acid addition, Termination: release of protein
Q3. What is genetic code? Write its features. (2 marks)
Answer: Triplet codon carries amino acid information, Universal, Non-overlapping, Degenerate
Q4. Explain law of segregation with a monohybrid cross example. (3 marks)
Answer: Alleles separate during gamete formation, Example: Aa x Aa produces 3:1 ratio in F2
Q5. What is linkage? Explain crossing over and recombination. (2 marks)
Answer: Genes on same chromosome inherited together, Crossing over exchanges genetic material creating new combinations
Q6. Describe the structure of DNA. Write Watson-Crick model features. (3 marks)
Answer: Double helix, Sugar-phosphate backbone, Nitrogenous bases paired (A-T, G-C), Antiparallel strands
Q7. What is gene expression? Explain central dogma of molecular biology. (2 marks)
Answer: Conversion of genotype to phenotype, DNA -> RNA -> Protein (central dogma)
Q8. Explain the process of photosynthesis with equation. (2 marks)
Answer: 6CO2 + 6H2O + light -> C6H12O6 + 6O2, Occurs in chloroplasts
Q9. What is respiration? Explain aerobic and anaerobic respiration. (3 marks)
Answer: Release of energy from food, Aerobic: requires O2, produces 38 ATP, Anaerobic: without O2, produces 2 ATP
Q10. Describe the structure and function of mitochondria. (2 marks)
Answer: Double membrane organelle, Inner folds = cristae, Site of ATP production, Oxidative phosphorylation
Q11. What is evolution? Explain Darwins theory of natural selection. (2 marks)
Answer: Change in organisms over time, Natural selection: survival of fittest, Environmental pressure selects favorable traits
Q12. Explain the different types of natural selection. (2 marks)
Answer: Stabilizing: favors intermediate phenotypes, Directional: favors one extreme, Disruptive: favors both extremes
Section C - Long Answer Questions — 33 marks
Attempt all questions. Each question carries 4 or 5 marks.
Q1. Explain spermatogenesis and oogenesis. Compare both processes. (5 marks)
Answer: Spermatogenesis: continuous in males, produces 4 functional sperms, Oogenesis: cyclic in females, produces 1 ovum and 3 polar bodies
Q2. Describe the menstrual cycle and hormonal regulation in females. (5 marks)
Answer: 28-day cycle, FSH and LH from pituitary regulate follicular and luteal phases, Estrogen and progesterone maintain cycle
Q3. Explain the process of photosynthesis with details of light and dark reactions. (5 marks)
Answer: Light reactions: electron transport, photolysis, ATP and NADPH formation in thylakoids, Dark reactions: Calvin cycle, CO2 fixation in stroma
Q4. Describe the structure of nephron and process of urine formation. (5 marks)
Answer: Glomerulus, Bowmans capsule, PT, LOH, DCT, Processes: ultrafiltration, selective reabsorption, secretion
Q5. Explain immune response. Describe humoral and cell-mediated immunity. (5 marks)
Answer: Defense against pathogens, Humoral: B cells produce antibodies, Cell-mediated: T cells destroy infected cells
Q6. Describe the process of dihybrid cross and proof of law of independent assortment. (4 marks)
Answer: Cross with two traits, F2 ratio 9:3:3:1, Proves genes on different chromosomes assort independently
Q7. Explain genetic engineering and its applications in agriculture and medicine. (4 marks)
Answer: Manipulation of DNA, Applications: GMO crops, production of insulin and vaccines, disease resistance
FAQs
What topics should be focused for Class 12 Biology board exam?
Reproduction, Genetics, Molecular Biology, Plant and animal physiology, Evolution, Ecology, and Biotechnology are key topics.
What is the exam pattern for Class 12 Biology?
70 marks with 3 hours duration, covering objective, short answer, and long answer questions on all Biology topics.
How to prepare diagrams effectively?
Practice drawing structures like cell, mitochondria, nephron, flower. Label all parts clearly. Understand the process each diagram represents.
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