Previous Year Paper — December 2025
Booklet NEE-3107-A · BSc / BSc BEd / ITEP BSc BEd, Fifth Semester, End Semester Examination, Dec 2025 · Botany, BOT-DSM-511 (Plant Physiology and Metabolism) · Time: 3 hours · Maximum marks: 60
The paper was bilingual (Hindi and English). This transcription is in English. Note on the cover: the question paper is divided into three sections; attempt the questions as per direction.
Section A — Objective Type Questions (10 x 1 = 10)
Choose the correct answer. Each question carries 1 mark. All 10 are compulsory.
- The movement of water from cell to cell is mainly due to differences in: (a) Osmotic pressure (b) Water potential (c) Root pressure (d) Diffusion pressure deficit
- Guttation occurs through: (a) Stomata (b) Hydathodes (c) Lenticles (d) Cuticle
- Which of the following is a micronutrient? (a) Nitrogen (b) Phosphorus (c) Magnesium (d) Zinc
- Which pigment acts as the primary electron donor in photosynthesis? (a) Chlorophyll b (b) Carotene (c) Chlorophyll a (d) Xanthophyll
- In glycolysis, one molecule of glucose produces: (a) 2 ATP (b) 4 ATP (c) 6 ATP (d) 8 ATP
- Assimilation of ammonia into amino acids is catalyzed by: (a) Nitrate reductase and nitrite reductase (b) Glutamate dehydrogenase and glutamine synthetase (c) Nitrogenase and ATPase (d) Hydrogenase and peroxidase
- Short-day plants flower when: (a) Day length is shorter than the critical period (b) Day length is longer than the critical period (c) Night length is shorter than the critical period (d) Temperature is high
- Phloem loading involves: (a) Active transport of sucrose into sieve tubes (b) Passive diffusion of ions (c) Osmosis of water (d) Root pressure
- Enzymes are mainly composed of: (a) Proteins (b) Carbohydrates (c) Lipids (d) Nucleic acids
- Nitrate reduction in plants takes place in: (a) Cytoplasm (b) Mitochondria (c) Chloroplast (d) Nucleus
Section A answer key
1 (b) Water potential — water moves from higher to lower water potential. 2 (b) Hydathodes — guttation is not through stomata. 3 (d) Zinc — nitrogen, phosphorus and magnesium are macronutrients. 4 (c) Chlorophyll a — the reaction-centre pigment and primary electron donor. 5 (a) 2 ATP net — gross production is 4 ATP, 2 ATP are used up. 6 (b) Glutamate dehydrogenase and glutamine synthetase (GS-GOGAT route). 7 (a) Day length shorter than the critical period, as framed by this paper — in modern terms, short-day plants respond to a long uninterrupted night exceeding a critical length. 8 (a) Active transport of sucrose into sieve tubes. 9 (a) Proteins. 10 (a) Cytoplasm — nitrate reductase is cytosolic; the next step, nitrite reduction, is in the chloroplast/plastid. Do not confuse the two.
Section B — Short Answer Type Questions (attempt any 4 of 6, 4 x 5 = 20)
Each question carries 5 marks.
- Explain the concept of water potential and discuss its components. [Unit 1]
- Write short notes on: (a) Role of macronutrients in plant growth (b) Components of phloem sap. [Units 1 + 2]
- Differentiate between C3, C4 and CAM pathways of photosynthesis. [Unit 3]
- Write a short note on the mechanism of enzyme catalysis. [Unit 4]
- Mention the role of auxins in plant growth. [Unit 5]
- What are the Pr and Pfr forms of phytochrome? How do they interconvert? [Unit 5]
Section C — Long Answer Type Questions (attempt any 3 of 5, 3 x 10 = 30)
Each question carries 10 marks.
- Describe the process of transpiration pull and its role in the ascent of sap. How does it compare with the contribution of root pressure? [Unit 1]
- Describe the process of biological nitrogen fixation. Explain the role of nitrogenase enzyme, the mechanism of nitrogen reduction and energy requirements. [Unit 4]
- Discuss the pressure flow (mass flow) model of translocation in phloem. Explain the mechanism of source-to-sink transport and provide experimental evidence supporting this theory. [Unit 2]
- Describe the Z-scheme of electron transport in photosynthesis. Explain the sequence of electron carriers and the generation of ATP and NADPH. [Unit 3]
- Explain the mechanism of oxidative phosphorylation. Describe the role of the electron transport chain and chemiosmotic theory in ATP synthesis. [Unit 3, respiration]
Pattern analysis
- Total: 10 + 20 + 30 = 60 marks, 3 hours. Choice exists only inside Section B (4 of 6) and Section C (3 of 5); Section A has no choice.
- Section A is broad and factual: definitions, one-step facts, names, sites and numbers. It rewards short notes and flashcards, not long essays. Every unit is tested even here: Unit 1 = Q1–Q3, Unit 3 = Q4–Q5, Unit 4 = Q6, Q9, Q10, Unit 2 = Q8, Unit 5 = Q7.
- Section B is roughly one question per major area, including two two-part short-note questions (B2). Answers need structure — definition, key points, example — about 1 to 1.5 pages each at exam speed.
- Section C is mechanism-heavy: transpiration pull, nitrogen fixation, pressure flow, Z-scheme, oxidative phosphorylation. Four of the five long questions ask for a mechanism plus evidence or comparison, not just a definition.
- Unit weight in this one paper (counting set questions, not attempted marks): Unit 1 is strong in A, B and C1; Unit 3 has two long questions plus B3 and A4/A5; Unit 4 has three MCQs plus B4 and C2; Unit 2 has A8, B2(b) and C3; Unit 5 has A7, B5 and B6 but no long question in this paper. Do not conclude Unit 5 cannot appear as a long question in another year — it is in the syllabus and B5/B6 show it is examined.
- Critical link to the class notes: almost every Section B/C topic in this paper — water potential, phloem sap, enzyme catalysis, phytochrome Pr/Pfr, transpiration pull, nitrogen fixation, pressure flow, Z-scheme, oxidative phosphorylation — was missing or only partial in the 46-page notes. Only auxins (B5) and the ATP-synthesis part of the Unit 3 questions were well covered. That is why this site teaches the full syllabus.
- Exam technique implied by the paper: for Section C, a diagram plus a stepwise mechanism plus 2–3 lines of evidence or comparison is the scoring pattern; for Section B, a short structured answer with a definition, components or factors, and one example each.