(Download) UPSC IFoS (Main) Exam Paper-2020 "Zoology"- II

Exam Name: IFoS (Main) Exam
Exam Year: 2020
Subject: "Zoology"- II

"SECTION- A'

1. (a) Explain the hormonal regulation of sex determination in mammals. 

(b) What is reverse transcription ? Explain it with an example. 

(c) Briefly explain Neo-Darwinism. 

(d) "Lysosomes are the suicidal bags of the cell.” Justify. 

(e) Define Cladistics. Comment on its significance. 

2. (a) Define Mutation. Explain various physical and chemical mutagens with suitable examples. 

(b) Give an illustrated account of the evolutionary history of horse.

(c) Briefly describe the modern methods of taxonomy for animals. 

Q3. (a) Explain the transport of large molecules across the plasma membrane. 

(b) What are Transposons ? Explain the general structure and mechanism of transposition of Tn3 elements in prokaryotes. 

(c) Differentiate between Parapatric and Sympatric speciation. 

4. (a) Describe with well-labelled diagram, the stages involved in Meiotic prophase. 

(b) Write an account of the methods of determination of the age of fossils.

(c) Give an account of the molecular mechanism of crossing over. 

'SECTION -B' 

Q5. (a) Describe the role of cholesterol in steroidogenesis.

(b) Explain how animals can survive in varying salinities. 

(c) Briefly describe the sliding filament theory of muscle contraction. 

(d) Illustrate the fate map of frog during gastrulation. 

(e) Differentiate between primary and secondary immune response. 

Q6. (a) Give a diagrammatic representation of citric acid cycle and discuss its role in metabolism. 

(b) Describe the process of synthesis, secretion, and action of acetylcholine during synaptic transmission. 

(c) Give a brief account of hormonal regulation of metamorphosis in insects. 

Q7. (a) Discuss the laws of thermodynamics and their applications in biological systems. 

(b) Define Apoptosis. Explain its mechanism with suitable example. 

(c) Discuss the structure of inner ear and explain its mechanism in hearing. 

Q8. (a) Give an account of the genetic basis of axis specification with one suitable example. 

(b) What is blood coagulation ? Enumerate the various steps involved in blood coagulation. 

(c) Define Teratogen. Briefly explain the different teratogenic agents. 

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