Zoology Optional Paper 2 Question Paper 2025 with Detailed Solution; Download PDF

UPSC Mains 2025 Question Paper for Zoology Optional Paper 2 is available here to download in PDF Format. The exam has been conducted on August 31, 2025, in Afternoon Session (02:30 PM to 05:30 PM). This Paper comprises 8 questions which are of 250 marks. The duration of the exam is 3 hours.

UPSC Mains Optional Paper 2 Zoology Question Paper 2025 with Detailed Solution; Download PDF (August 31, 2025)

Q1 (A)  Protein sorting in Golgi apparatus

Q1 (B)  Structure and function of Lampbrush chromosome

Q1 (C)  Symptoms, causes and treatment of thalassemia

Q1 (D)  Coupling and repulsion phases of linkage

Q1 (E)  Sympatric and allopatric speciation

Q2 (A) (i)  Describe composition of plasma membrane.

Q2 (A) (ii)  Differentiate between facilitated and passive diffusion across the membrane with examples.

Q2 (B)  Explain how mutations affect variations in population and natural selection.

Q2 (C)  Draw pedigrees for autosomal recessive and sex-linked inheritance using examples from human.

Q3 (A) (i) Describe the synthetic theory of evolution.

Q3 (A) (ii)  Describe common types of mimicry in insects with suitable examples.

Q3 (B)  Discuss the process of chain elongation during protein synthesis in prokaryotes.

Q3 (C)  Describe the mechanism of ribozyme action and comment on its technological applications.

Q4 (A)  Describe the steps of constructing a recombinant DNA and its cloning.

Q4 (B)  Discuss the major morphological modifications during horse evolution.

Q4 (C)  Write down the salient features of zoological nomenclature.

Q5 (A)  Write short note in 150 words: Block to polyspermy

Q5 (B)  Write short note in 150 words: Fate map of frog embryo

Q5 (C)  Write short note in 150 words: Activation energy based mechanism of enzyme action

Q5 (D)  Write short note in 150 words: Structure of dipeptide unit of a protein

Q5 (E)  Write short note in 150 words: Transmission of nerve impulse through synapse

Q6 (A) (i)  Write down the reactions that produce NADH during Krebs cycle.

Q6 (A) (ii)  Explain the role of proton gradient in oxidative ATP synthesis.

Q6 (B) Describe characteristic features and specific functions of lymphocytes, monocytes and neutrophils.

Q6 (C)  Diagrammatically describe the steps of development of heart in mammals.

Q7 (A) (i)  Explain sigmoidal nature of oxygen dissociation curve for hemoglobin.

Q7 (A) (ii)  Describe differences between adult and fetal hemoglobin and comment on their physiological significance.

Q7 (B)  Discuss the mechanism of action of cytotoxic-T cell.

Q7 (C)  What are homeotic genes? Explain their role in body axis formation in chick.

Q8 (A)  Describe the stages of fertilization in chick with diagram.

Q8 (B)  Draw structure of cholesterol and explain its role in health and diseases.

Q8 (C)  Discuss the role of ovarian hormones in female reproduction.

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