Green plants make their own food by photosynthesis. During this process carbon dioxide form the atmosphere is taken in by leaves through stomata and used for making carbohydrates, principally glucose and starch. Photosynthsis takes place only in the green parts of the plants, mainly the leaves. Within the leaves, the mesophyll cells have a large number of chloroplasts that are responsible for CO2 fixation. Within the chloroplasts, the membranes are sites for the light reaction, while the chemosynthetic pathway occurs in the stroma. photosynthesis has two stages the light reaction and the carbon fixing reations. in the light reaction the light energy is absorbed by the pigments present in the antenna and funnelled to special chlorophyll a molecules called reaction centre chlorophylls there are two photosystems, PS I and PS II. PS I has a 700 nm absorbing chlorophyll a P700 molecule at its reaction center, while PS II has a P680 reaction centre that absorbs red loght at 680 nm After absorbing light, electrons are excited and transferred through PS II and PS I and finally to NAD forming NADH. during this process a proton gradient due to movement through the thylakoid The breakdown of the protons gradient due to movement through the F0 part of the ATPase enzyme releases enough energy for synthesis of ATP splitting of water molecles is associated with PS II resulting in the release of O2, protons and transfer of electrons to PS II In the carbon fixation cyale, CO2 is added by the enzyme, RuBisCO, to a 5 carbon compound RuBP that is converted to 2 molecules of 3- carbon PGA. this is then converted to sugar by the Calvin cycle, and the RuBp is regenerated. During this process ATP and NADPH synthesised in the light reaction are utilsed RuBisCO also catalyses a wasteful oxygenation reaction in C3 plants: Photorespiration Some tropical plants show a special type of photosynthesis called C4 pathway in these plants the first product of CO2 fixation that takes place in the mesophyll, is a 4-carbon compound. in the bundle sheath cells the Calvin pathway is carried out for the synthesis of carbohydrates.
4. The approximate dimension of chlorophyll porphyrin ring is.
(A) 1 Ao square (B) 5 Ao square (C) 10 Ao square (D) 15 Ao square
5. Photosynthesis is most active in
(A) sunlight (B) yellow (C) red (D) green
6. Intensity of light increase 20 times, rate of photosynthesis will
(A) increase (B) not increase
(C) decrease (D) increase till feed back inhibition.
7. Out of the total light energy that is available for plants is
(A) 50 % (B) 75 % (C) 25 % (D) 1––2%
8. One photon is blue light contains____kcal and of red light___kcal
(A) 70 ; 40 (B) 220 ; 70 (C) 10 ; 90 (D) 90 ; 10
9. The most efficient convertor of sunlight is
(A) Potato (B) Tomato (C) Sugar cane (D) Papaya
10. Cyclic photophosphorylation is confined to
(A) Photosystem I (B) Photosystem II
(C) both a & b (D) none above
11. For synthesis of one gram of hexose, the land plant consumes.
(A) Only 1/3 of the CO2 of air (B) Only 1/4 of the CO2 of air
(C) Only 2/3 of the CO2 of air (D) none of the above
12. For synthesis of one glucose molecule, the number of ATP required are
(A) 9 ATP for C3 cycle and 20 ATP for C4 cycle
(B) 18 ATP for C3 cycle and 30 ATP for C4 cycle
(C) 22 ATP for C3 cycle and 35 ATP for C4 cycle
(D) 24 ATP for C3 cycle and 36 ATP for C4 cycle
13. The volume of O2 librated in photosynthesis has the following ratio to CO2.
(A) O2/CO2 = 1 (B) O2/CO2 = 1/2
(C) O2/CO2 = 2/1 (D) O2/CO2 = 3/1
14. The inhibiting effect of oxygen in C3 plants on photosynthesis is
(A) solarization (B) photooxidation
(C) Warbug’s effect (D) none above
15. Pick up C4 plant.
(A) Papaya (B) Potato (C) Maize (D) Pea
16. It is advantageous to use a water plant to demonstrate photosynthesis other than a land plant because.
(A) it photosynthesize rapidly (B) it respires slowly
(C) it does not transpire (D) O2 bubbles from cut and can be collected over H2O.
17. For chlorophyll formation most important are
(A) Fe++ and Ca++ (B) Fe++ and Mg++ (C) Mg++ and Ca++ (D) all the above
18. Translocation of sugar in angiosperms occur in form of
(A) glucose (B) starch (C) lactose (D) sucrose
19. Q10 is
(A) respiratory coefficients (B) photosynthetic coefficient
(C) photosynthetic yield (D) temperature coeffiecient
20. Photorespiration is favoured by
(A) low temperatures (B) low light intensity
(C) high O2 and low CO2 (D) low O2 and high CO2
20. Photorespiration is favoured by
(A) low temperatures (B) low light intensity
(C) high O2 and low CO2 (D) low O2 and high CO2
21. Quinones are
(A) mobile electron carriers (B) enzymes of oxidative phosphorylation
(C) enzymes of krebs cycle (D) none of the above
22. During dark reaction, for the fixation of carbon, the three carbon atoms of each molecule of 3 –phosphogylceric acid (PGA) are derived from
(A) RuBP only (B) CO2 only
(C) RuBP + CO2 (D) RuBP + CO2 + PEP.
23. Calvin cycle utilize for fixation of 3 molecules of CO2
(A) 9 ATP and 6 NADPH2 (B) 8 ATP and 8 NADPH2
(C) 9 ATP and 3 NADPH2 (D) 6 ATP and 6 NADPH2
24. Chloroplast has maximum quantity of___in stroma
(A) dehydrogenase (B) RuBP carboxylase
(C) pyruvic carboxylase (D) hexokinase
25. If thylakoids are removed and kept in culture medium having CO2 and H2O and exposed to light ;they cannot form hexose sugars as end product because.
(A) light trapping device absent (B) pigments P-700 and P-680 not linked
(C) CO2 assimilating enzymes absent (D) CO2 assimilation cannot occur in light
26. Which of the following plant is efficient converter of solar energy whose net productivity 2-4 kg/m2/yr or even higher.
(A) Wheat (B) rice (C) sugarcane (D) bajra
27. The number of photons required to release one mole of O2 in photosynthesis called.
(A) quantum yield (B) quantum requirement
(C) red drop (D) Emerson’s effect
28. Calvin cycle represents one of the following phenomenon.
(A) oxidative carboxylation (B) dark phosphorylation
(C) dark respiration (D) reductive carboxylation
29. Hill reaction takes place
(A) in the absence of CO2
(B) in the presence of carbon dioxide
(C) in the absence of a suitable electron acceptor
(D) none above
32. The basic feature of typical C4 plants showing ‘Kranz’ anatomy is
(A) the presence of chloroplasts in mesophyll and epidermal cells
(B) the presence of chloroplasts in bundle sheath cells
(C) the presence of rudimentary chloroplasts in bundle sheath cells and typical chloroplasts withwell-formed grana in mesophyll cells
(D) the presence of typical chloroplasts with well-formed grana in bundle sheath cells and rudimentary chloroplasts in the mesophyll cells
33. A. Six turns of Calvin-cycle result in the production of one molecule of glucose (C6H12O6)
R. Three molecules of ribulose 1, 5 – bisphosphate (Ru BP) react with three molecules of carbon dioxide to produce six carbon intermediates.
(A) A is correct and R is its explanation (B) A is correct but R is not its explanation
(C) A is correct but R is wrong (D) Both A and R are wrong
34. Maximum photosynthesis occurs in which of these lights ?
(A) Red (B) Green
(C) Very high light (D) Continuous bright light
35. In C4 plants showing Kranz anatomy which of the following is correct ?
(A) Bundle sheath cells without grana and mesophyll cells with grana
(B) bundle sheath cells with grana mesophyll cells without grana
(C) both are without grana
(D) both are with grana
36. In Blackmann’s ‘Law of Limiting Factors’ the rate of photosynthesis continues to increase with thesuccessive increase in the amounts of
(A) carbon dioxide, light, temperature (B) temperature, light, carbon dioxide
(C) light, temperature, carbon dioxide (D) light, carbon dioxide, temperature
37. Choose the correct statement
(A) Chl a is blue green pigment with formula C55H70O6N4Mg
(B) Chl a is blue green pigment with formula C55H72O5N4Mg
(C) Chl b is yellow green pigment with formula C55H70O5N4Mg
(D) Xanthophyll is pigment with formula C40H60
38. Chlorophyll a is absent in which of the following photosynthesising organisms ?
(A) Bacteria (B) Cyanobacteria (C) Red algae (D) Brown algae
39. Photorespiration in C3 plants starts from.
(A) phosphoglycerate (B) phosphosglycolate (C) glycerate (D) glycine
40. Which one of the following is wrong in relation to photorespiration ? It
(A) occurs in chloroplasts (B) occurs in daytime only
(C) is a characteristic of C4 plants (D) is a characteristic of C3 plants
