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Plant Physiology (GATE - XL)

Description: GATE NET SLET
Number of Questions: 15
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Tags: GATE NET SLET Photosynthesis
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Which of the following is/are an example of crassulacean acid metabolism plant?

  1. Swan potato

  2. Sorghum

  3. Millets

  4. Soybean

  5. Spinach

Show answer
Correct Option: A
Explanation:

Swan potato is an example of CAM (crassulacean acid metabolism) plants. CAM is named after the family Crassulaceae. CAM stands for crassulacean acid metabolism because it was first studied in the members of plant family Crassulaceae, to which swan potato plant belongs.

Which of the following statements are correct about C4 plants?

A. CO2 fixation occurs twice. B. PEP acts as CO2 acceptor in bundle sheath. C. Leaf anatomy is of Kranz type. D. They require 18 ATP for synthesis of one molecule of glucose.

  1. A and B

  2. A and C

  3. B and C

  4. B and D

  5. C and D

Show answer
Correct Option: B
Explanation:

This option is correct because in C4 plants, CO2 fixation occurs twice, once in mesophyll cells to form oxaloacetic acid and another in bundle sheath cells to form 3-phosphoglyceric acid. Kranz-type leaf anatomy is found in C4 plants.

Which of the following statements are incorrect about photo system I?

A. PS I lies in outer surface of thylakoids. B. Reaction centre of PS I is P680. C. It participates in both cyclic as well as non-cyclic phosphorylation. D. Molecular oxygen is evolved as a result of photolysis of water.

  1. A and B

  2. A and C

  3. A and D

  4. B and C

  5. B and D

Show answer
Correct Option: E
Explanation:

This option is correct because reaction centre of PS I is P700 and molecular oxygen is not evolved in PS I. It is evolved as a result of photolysis of water in PS II.

Which of the following photosynthetic pigments are found in higher plants and green algae?

  1. Chlorophyll a
  2. Chlorophyll b
  3. Chlorophyll c
  4. Phycobilins

  1. 1 and 2

  2. 2 and 3

  3. 2 and 4

  4. 3 and 4

  5. 1 and 3

Show answer
Correct Option: A
Explanation:

This option is correct because all plants, algae and cyanobacteria, which photosynthesise, contain chlorophyll a and chlorophyll b occurs only in green algae and in plants.

Which of the following statements are incorrect about photosynthesis?

  1. Best photosynthesis takes place in green light.
  2. Quantum yield of photosynthesis is 0.125.
  3. Energy conversion efficiency of photosynthesis is 66%.
  4. 90% of the total photosynthesis in the world is carried out by marine algae.

  1. 1 and 2

  2. 1 and 3

  3. 1 and 4

  4. 2 and 3

  5. 3 and 4

Show answer
Correct Option: B
Explanation:

This option is correct because energy conversion efficiency of photosynthesis is 33% and best photosynthesis takes place in red light, next best in blue light and nil in green light.

Which of the following statements are correct about non-cyclic phosphorylation?

  1. It is an oxygenic process.
  2. Only one light trapping system (PS I) is involved.
  3. No NADPH is synthesised.
  4. NADP acts as last electron acceptor.

  1. 1 and 2

  2. 1 and 3

  3. 2 and 3

  4. 1 and 4

  5. 3 and 4

Show answer
Correct Option: D
Explanation:

This option is wrong because non-cylic phosphorylation is an oxygenic process, i.e. oxygen is given off during the process and NADP acts as last electron acceptor in non-cyclic phosphorylation.

Choose the incorrect reaction.

  1. Ribulose-1,5-bisphosphate → 3-phosphoglycerate: Rubisco

  2. 3-Phosphoglycerate → Glycerate-1,3-bisphosphate: Phosphoglycerate kinase

  3. Dihydroxy acetone phosphate → Fructose 1,6-bisphosphate: Aldolase

  4. Xylulose 5-phosphate → Ribulose 5-phosphate: ribose-5-phosphate isomerase

  5. Ribulose 5-phosphate → Ribulose-1,5-bisphosphate: Phosphoribulokinase ribose 5-phosphate isomerise

Show answer
Correct Option: D
Explanation:

Conversion of xylulose 5-phosphate to ribulose 5-phosphate is catalysed by ribulose-phosphate epimerase. Conversion of ribose 5-phosphate to ribulose 5-phosphate is catalysed by ribose 5-phosphate isomerise.

Which of the following statements is/are not correct about C3 plants?

  1. C3 plants occur only in tropical region climates.
  2. Leaves show Kranz anatomy.
  3. Mesophyll cells are not differentiated.
  4. Bundel sheath is absent.

  1. 1 and 2

  2. 1, 2 and 3

  3. 2, 3 and 4

  4. Only 3

  5. Only 4

Show answer
Correct Option: B
Explanation:

This option is correct because C3 plants occur in all types of climates, whereas C4 plants occur in tropical region climates. Leaves of C3 plants do not show Kranz anatomy and mesophyll cells are differentiated in C3 plants.

Match the following:

 
Scientists Their contribution
P. Emerson and Arnold 1. O2 comes from H2O in photosynthesis
Q. Ruben and Kamen 2. Chloroplasts as the site of photosynthesis
R. Arnon 3. Mechanism of phosphorylation in chloroplast
S. Engelmann 4. Existence of light and dark reaction in photosynthesis

  1. P - 2, Q - 1, R - 3, S - 4

  2. P - 2, Q - 3, R - 4, S - 1

  3. P - 3, Q - 1, R - 4, S - 2

  4. P - 3, Q - 4, R - 2, S - 1

  5. P - 4, Q - 2, R - 3, S - 1

Show answer
Correct Option: C
Explanation:

This option is correct because all are correctly matched. In 1932, Emerson and Arnold proved the existence of light and dark reaction in photosynthesis. In 1939, Samuel Ruben and Martin Kamen used radioactive isotopes to determine that the oxygen liberated in photosynthesis came from the water. In 1954, Arnon discovered the mechanism of phosphorylation in chloroplasts. In 1881, Theodore Engelmann identified chloroplasts as the site of photosynthesis.

Which of the following herbicides do not interfere in light reaction of photosynthesis?

P. 2,4-D Q. Diuron R. Glyphosate S. Atrazine

  1. P and Q

  2. P and R

  3. P and S

  4. Q and R

  5. Q and S

Show answer
Correct Option: B
Explanation:

This option is correct because 2,4-D and gyphosate do not act as interfering in light reaction of photosynthesis. 2,4-D is a synthetic auxin herbicide, have several points of action on the cell membrane and are effective in the control of dicot plants. Glyphosate is a systemic enolpyruvylshikimate 3-phosphate synthase (EPSPS) enzyme inhibitor herbicide.

The raw materials for dark reaction are

  1. CO2, NADPH2 and ATP

  2. Water, ADP and H3PO4

  3. NADP, H3PO4 and ADP

  4. NADPH2, ATP and O2

  5. Hexose sugar

Show answer
Correct Option: A
Explanation:

CO2, NADPH2 and ATP act as the raw materials for dark reaction.

Match the following:

 
Column – I (Scientists) Column – II (Their contribution)
P. Hill and Bendal 1. Z-scheme of light reaction
Q. Peter Mitchell 2. Chemiosmotic hypothesis of ATP synthesis in light reaction
R. Hatch and Slack 3. C3 pathway for CO2 fixation
S. Melvin Calvin 4. C4 pathway for CO2 fixation

  1. P - 1, Q - 2, R - 3, S - 4

  2. P - 2, Q - 1, R - 4, S - 3

  3. P - 3, Q - 2, R - 1, S - 4

  4. P - 4, Q - 3, R - 2, S - 1

  5. P - 1, Q - 2, R - 4, S - 3

Show answer
Correct Option: E
Explanation:

Correct answer. In 1960, Hill and Bendal suggested Z-scheme of light reaction. In 1961, Peter Mitchell proposed chemiosmotic hypothesis of ATP synthesis in light reaction. In 1966, Hatch and Slack reported the C4 pathway for CO2 fixation in certain tropical plants. In 1954, Melvin Calvin traced the path of carbon in photosynthesis and gave the C3 cycle (now known as Calvin cycle).

Which of the following statements are correct about dark reaction?

P. Source of energy for dark reaction is ATP synthesised in light reaction. Q. Raw materials of dark reaction are water, ADP and H3PO4. R. Oxygen is a by-product of dark reaction and is released in the atmosphere. S. Dark reaction occurs in stroma of chloroplast.

  1. P and Q

  2. P and R

  3. P and S

  4. Q and R

  5. R and S

Show answer
Correct Option: C
Explanation:

This option is correct because source of energy for light reaction is sunlight whereas source of energy for dark reaction is ATP synthesised in light reaction. The site for action of dark reaction is stroma of chloroplast.

Directions: In the following question, there are two statements, Assertion (A) and Reason (R). Consider both the statements independently and mark your answer. Assertion: The inhibition of glycolysis by oxygen is referred to as Pasteur effect. Reason: This is due to inhibition of the enzyme phosphofructokinase by ATP and citrate (formed in the presence of O2).

  1. A and R both are correct and R is the correct explanation of A.

  2. A and R both are correct and R is not the correct explanation of A.

  3. A is correct and R is incorrect.

  4. A is incorrect and R is correct.

  5. A and R both are incorrect.

Show answer
Correct Option: A
Explanation:

This option is correct because the inhibition of glycolysis by oxygen is referred to as Pasteur effect. This is due to inhibition of the enzyme phosphofructokinase by ATP and citrate (formed in the presence of O2).

Which of the following statements is/are not correct about chlorophyll?

  1. The metal constituent of chlorophyll is Fe.
  2. Chlorophyll is found associated with thylakoid membranes.
  3. Long-chain alcohol esterified to plant chlorophyll molecules is farnesol.

  1. Only 1

  2. Only 2

  3. Only 3

  4. 1 and 2

  5. 1 and 3

Show answer
Correct Option: E
Explanation:

This option is correct because the metal constituent of chlorophyll is Mg and long-chain alcohol esterified to plant chlorophyll molecules is phytol.

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