IGNOU BBYCT-137 December 2025 Previous Year Question Paper

Q1.(a) State whether the following statements are True or False : 4x1=4

(6) Phosphoenol Pyruvate (PEP) generates NADPH in place of NADP.

(ii) The element sodium plays a key role in maintaining the turgor of plant cells.

(iii) RuBP has a higher affinity for CO, than PEP.

(iv) Ethylene is a gaseous hydrocarbon.

(b) Fillin the blanks : 4x1=4

(i) The upward movement of water is

(1) Sugars are produced in of Ca plants.

(ii) we protects nitrogenase against oxygen. sensitivity in leguminous plants.

(iv) ww... is the most widely distributed naturally occurring auxin.

(c) Match the items given under Column A with those given in Column B: 4x5=2 Column A Column B (@) CoenzymeA

(1) Nitrate reductase Gi) Haem

(2) Urease Gii) Sumner

(8) Catalase

(iv) Cobalt

(4) Vitamin derived coenzyme

Q2.Differentiate between the following pairs of terms : 4x2.5=10

(a) Diffusion and Osmosis

(b) Cs and C, plants

(c) Competitive and Non-competitive inhibition

(d) Transpiration and Guttation

Q3.(a) Explain water potential and_ its components. 5

(b) Give a brief account on _ the photorespiration process.

Q4.(a) Give a detailed account on the structure and functions of Photosystem-II. 5

(b) Explain the chemiosmatic model mechanism for ATP synthesis.

Q5.(a) Briefly describe the radial movement of ions in roots. 5

(b) What is oxidative stress and how does it affect plants ?

Q6.(a) Discuss the various factors that affect the enzyme activity. 5

(b) Describe how auxins affect plant growth.

Q7.Write short notes on any four of the following : 4x2.5=10

(a) Phycobilins

(b) Biological Nitrogen fixation

(c) Synthetic Growth Hormones

(d) Photoperiodism

(e) Carrier proteins 4x1=4 4x2.5=10 4x2.5=

(10)