CSS past paper

CSS Botany Past Paper 2025

CSS Botany 2025 carries 100 marks over 3 hours. It has 7 questions.

Marks: 100
Time: 3 hours
Questions: 7

Years

How to attempt: Attempt ONLY FOUR questions from PART-II. ALL questions carry EQUAL marks.

Questions

Question 1 (Part I) is the paper's MCQs, which are not reproduced here.

Q. 2
How does the chemiosmotic theory explain ATP synthesis during oxidative phosphorylation? What is the significance of the proton gradient across the inner mitochondrial membrane?
(20)
Q. 3
Describe the interaction between cytokinins and auxins in regulating plant growth and development, with specific examples of their synergistic and antagonistic effects.
(20)
Q. 4
What are the primary causes of soil salinity and waterlogging in Pakistan? How do these issues impact agricultural productivity? Discuss with reference to specific regions and irrigation practices. Evaluate the effectiveness of government policies and initiatives in addressing waterlogging and salinity in Pakistan.
(20)
Q. 5
Explain the role of molecular techniques in the diagnosis, identification, and management of plant pathogens. Provide specific examples of their application in Pakistan.
(20)
Q. 6
(20)
- (a)
  What are chromosomes? Explain their structure and role in inheritance.
  (10)
- (b)
  Discuss the various mechanisms of genetic variability in fungi and their significance in fungal evolution.
  (10)
Q. 7
How do convergent and divergent evolutions differ? Provide examples from nature. Also, describe the processes of genetic drift, gene flow, and mutation, and their contributions to evolution.
(20)
Q. 8
(20)
- (a)
  Discuss the stages of embryonic development in angiosperms, highlighting key events in the formation of the embryo sac and zygote.
  (10)
- (b)
  What is double fertilization in angiosperms? Discuss its significance and the development of the endosperm.
  (10)

Part-II is to be attempted on the separate Answer Book.
Attempt ONLY FOUR questions from PART-II. ALL questions carry EQUAL marks.
All the parts (if any) of each Question must be attempted at one place instead of at different places.
Write Q. No. in the Answer Book in accordance with Q. No. in the Q.Paper.
No Page/Space be left blank between the answers. All the blank pages of Answer Book must be crossed.
Extra attempt of any question or any part of the question will not be considered.