PLANT PHYSIOLOGY (Part-I)

21. Which light is least effective in photosynthesis? [S.S.C. Online Graduate Level (T-I) 9.09.2016 (Shift-II)]

(a) Blue light
(b) Green light
(c) Red light
(d) Sunlight

Correct Answer: (b) Green light

Solution:Green light -
Green light is least effective in photosynthesis because chlorophyll, the primary pigment in plants, reflects green light rather than absorbing it. This is why plants appear green to our eyes.

22. The maximum fixation of solar energy is done by- [S.S.C. Online Graduate Level (T-I) 9.09.2016 (Shift-II)]

(a) Bacteria
(b) Protozoa
(c) Fungi
(d) Green plants

Correct Answer: (d) Green plants

Solution:In the process of photosynthesis, green plants take the energy of light from the sun, carbon dioxide (CO₂) taken from the air, and water absorbed from the soil to form carbohydrates and releases oxygen (O₂) as a byproduct.
6CO₂ + 12H₂O → C₆H₁₂O₆ + 6H₂O + 6O₂ ↑

23. Which of the following is not required for photosynthesis? [S.S.C. Online Stenographer 13.09.2017 (Shift-I)]

(a) Water
(b) Sunshine
(c) Chloroplast
(d) Oxygen

Correct Answer: (d) Oxygen

24. Which of the following gases is released in the process of photosynthesis? [S.S.C. Online C.H.S.L. (T-I) 12.08.2021 (Shift-III)]

(a) Nitrous dioxide
(b) Nitrogen
(c) Oxygen
(d) Carbon dioxide

Correct Answer: (c) Oxygen

Solution:Oxygen -
Photosynthesis uses carbon dioxide and water to produce glucose (a sugar) and releases oxygen as a byproduct.

25. In which of the following processes oxygen is not used? [S.S.C. Online MTS (T-I) 5.10.2017 (Shift-III)]

(a) combustion
(b) respiration
(c) Oxide formation of nitrogen
(d) photosynthesis

Correct Answer: (d) photosynthesis

Solution:Photosynthesis -
Photosynthesis is the process where plants use light energy to convert carbon dioxide and water into glucose and oxygen. Oxygen is produced, not consumed, in this process. Combustion, respiration, and the oxide formation of nitrogen all involve the use of oxygen.

26. The oxygen liberated during photosynthesis comes from— [S.S.C. Online Graduate Level (T-I) 3.09.2016 (Shift-I)]

(a) Water
(b) Carbon dioxide
(c) Glucose
(d) Chlorophyll

Correct Answer: (a) Water

Solution:Water -
The oxygen liberated during photosynthesis comes from the splitting of water molecules (photolysis).

27. The source of O₂ liberated in photosynthesis is [S.S.C. Online MTS (T-I) 4.10.2017 (Shift-II)]

(a) Sunlight
(b) Carbohydrate
(c) Water
(d) Carbon dioxide

Correct Answer: (c) Water

Solution:Water -
Similar to the previous question, the source of the oxygen released during photosynthesis is water.

28. The liberation of oxygen during photosynthesis is due to ______ . [S.S.C. Online Graduate Level (T-I) 31.08.2016 (Shift-III)]

(a) Hydrolysis of carbohydrates
(b) Photolysis of water
(c) Reduction of CO₂
(d) Breakdown of chlorophyll

Correct Answer: (b) Photolysis of water

Solution:Photolysis of water -
The splitting of water molecules into hydrogen ions, electrons, and oxygen gas, driven by light energy, is known as photolysis and is responsible for the release of oxygen during photosynthesis.

29. Which among the following is NOT an event during the photosynthesis process? [S.S.C. Online CHSL (T-I) 8.03.2018 (Shift-II)]

(a) Absorption of light energy by chlorophyll
(b) Conversion of light energy into chemical energy
(c) Splitting of water molecules into Hydrogen and Oxygen
(d) Oxidation of Carbon dioxide to carbohydrates

Correct Answer: (d) Oxidation of Carbon dioxide to carbohydrates

Solution:Oxidation of Carbon dioxide to carbohydrates -
During photosynthesis, carbon dioxide is reduced to carbohydrates (like glucose), not oxidized. Oxidation involves the loss of electrons or an increase in oxidation state, while reduction involves the gain of electrons or a decrease in oxidation state.

30. The process of photosynthesis takes place in the presence of— [S.S.C. Online MTS (T-I) 19.08.2019 (Shift-II)]

(a) Sulfur
(b) Chlorophyll and sunlight
(c) Nitrogen
(d) Cadmium

Correct Answer: (b) Chlorophyll and sunlight

Solution: Chlorophyll and sunlight -
Photosynthesis requires the presence of chlorophyll to capture light energy and sunlight as the energy source to drive the process.