PDF Question Bank Photosynthesis - Testlabz

[Pages:16]Question Bank Photosynthesis

1. Name the following :

(i) The first stable product of CO2 fixation in plants. (ii) The CO2-acceptor molecule in plants. (iii) The part of chloroplast where Calvin cycle operates.

(iv) The source of oxygen during photosynthesis.

(v) The final products of light reaction.

(vi) In which form are the carbohydrates translocated in plants?

(vii) The plant tissue which takes part in translocation of food material within

the plant body.

(viii) The universal hydrogen acceptor in plants.

(xi) A plant which does not perform photosynthesis.

Ans.(i) Phosphoglyceric acid (ii) Ribulose biphosphate (iii) Stroma (v) ATP and NADPH+ (vii) Phloem (ix) Fungus

(iv) Water (vi) Sucrose (viii) NADP

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2. Complete the following statements by choosing the correct alternative out

of those given in brackets.

(i) Carbon dioxide is necessary for _________. [Respiration / Photorespiration /

Photosynthesis]

(ii) Animal nutrition is mostly __________. [Autotrophic / Heterotrophic/

Parasitic]

(iii) Chlorophyll molecule has a _________ in the middle of the ring structure.

[Nitrogen, Manganese, Magnesium]

(iv) Splitting of water results in the release of __________ . [Oxygen / Water /

Oxygen and water]

(v) Presence of starch can be tested by ___________. [Iodine / Hydrochloric acid /

Alcohol]

Ans.(i) Photosynthesis

(ii) Heterotrophic

(iii) Magnesium

(iv) Oxygen

(v) Iodine.

3. Mention if the following statements are true or false. If false, rewrite the

wrong ones by changing only the words printed in bold face.

(i) Light reaction is called thermo-chemical reaction.

(ii) Oxygen evolved during light reaction is from carbon dioxide.

(iii) A plant can be destarched by keeping it in dark for 48 hours.

(iv) Stroma is the site of light reaction.

(v) Potassium hydroxide absorbs oxygen.

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Ans.(i) False (Photochemical) (ii) False (Water) (iii) True (iv) False (Thylakoid) (v) False (Carbon dioxide).

4. Give the overall chemical equation of photosynthesis.

Ans.

6CO2

+ 12H2O

Sunlight Chlorophyll

6O2

+

(CH2O)6

+

6H2O

5. What will be the effect of excess oxygen on the process of photosynthesis? Ans. Photosynthesis will be inhibited.

6. Why is Calvin cycle called C3 cycle? Ans. Calvin cycle is called C3 cycle because the first stable compound formed

is phosphoglyceric acid (PGA) which has three carbon atoms. 7. Name the main steps of dark reaction. Ans. Carboxylation, glycolytic reversal and regeneration of RuBP. 8. Give the full form of NADP. Ans. Nicotinamide adenine dinucleotide phosphate.

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9. (a) What is photolysis of water?

(b) What is the function of chlorophyll pigment?

Ans. (a) Light induced splitting of water molecule into its two component ions,

H+ and OH?, is called photolysis of water. (b) During light reaction of photosynthesis solar energy is trapped by

chlorophyll which is used for the photolysis of water and ATP formation.

10. (a) What is photosynthesis?

(b) What is the role of light in photosynthesis? Ans. (a) Photosynthesis is a physiological process by which green parts of the

plant, in the presence of sunlight, prepare food in the form of carbohydrates

and release oxygen as a by-product.

(b) Light energy is absorbed by chlorophyll and transformed into chemical

energy which causes splitting of the water molecule, formation of NADPH2 and ATP which is used for the reduction of carbon dioxide to glucose.

11. (a) All life would come to an end if there were no green plants. Comment.

(b) How is the light reaction linked to the dark reaction?

Ans. (a) Green plants are the primary producers on the earth. That is, they fix up

atmospheric CO2, utilising light, chlorophyll and water, and synthesise

food material. This food is utilised by different heterotrophs in the

ecosystem. In addition, the plants release oxygen during the photosynthetic

process and thus maintain the balance of oxygen in the atmosphere.

Oxygen is used by all organism for their respiratory activity.

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(b) During light reaction, ATP and NADPH are generated. These two compounds are used in the dark reactions during the reduction of 3 PGA to phosphoglyceraldehyde.

12. (i) Describe the structure of chloroplast through a well-labelled diagram. (ii) Suggest some habitats or natural circumstances in which (a) light intensity, (b) carbon dioxide concentration, (c) temperature will be limiting factors in photosynthesis.

Ans. (i) Chloroplasts measure about 4-10 m in diameter and 1-3 m in thickness. Each chloroplast is bound by a double membrane. Inside the membranes is the ground substance, the stroma, in which lie a system of chlorophyllbearing double-membraned sacs stacked one above the other to form grana. Individual sacs in each lamellae are known as thylakoids.

(ii) Some likely situations would be

(a) In a shaded community; dawn and twilight in a warm climate.

(b) CO2 is normally limiting, but it would be more so in a place cluttered

with plants under sunny warm conditions.

(c) A bright winter day.

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