Photosynthesis in Higher Plants – Daily Practice Problem (DPP)

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🎯 NEET 2026 Daily Practice Problem (DPP)

Topic: Photosynthesis in Higher Plants | 20 High-Yield MCQs

Q1. Who demonstrated that photosynthesis is essentially a light-dependent reaction in which hydrogen from a suitable oxidisable compound reduces carbon dioxide to carbohydrates?

  1. Julius von Sachs
  2. Cornelius van Niel
  3. Jan Ingenhousz
  4. T.W. Engelmann
✅ View Answer & Explanation

Correct Answer: (2) Cornelius van Niel
Explanation: Van Niel’s studies on purple and green sulfur bacteria led to the inference that O_2 evolved from H_2O, not CO_2.

Q2. The reaction centre in Photosystem II (PS II) has an absorption peak at:

  1. 700 nm
  2. 680 nm
  3. 660 nm
  4. 400 nm
✅ View Answer & Explanation

Correct Answer: (2) 680 nm
Explanation: PS II reaction centre is called P680. PS I has an absorption peak at 700 nm (P700).

Q3. Which of the following is NOT required for the chemiosmotic synthesis of ATP?

  1. Proton pump
  2. Proton gradient
  3. ATP synthase
  4. PS I only
✅ View Answer & Explanation

Correct Answer: (4) PS I only
Explanation: Chemiosmosis requires a membrane, a proton pump, a proton gradient, and ATP synthase (F_0-F_1 particle).

Q4. The first stable product of CO_2 fixation in C_3 plants is:

  1. Oxaloacetic acid (OAA)
  2. 3-phosphoglyceric acid (PGA)
  3. Phosphoenolpyruvate (PEP)
  4. Ribulose biphosphate (RuBP)
✅ View Answer & Explanation

Correct Answer: (2) 3-phosphoglyceric acid (PGA)
Explanation: In the Calvin cycle (C_3 pathway), the first stable product is a 3-carbon acid, 3-PGA.

Q5. Kranz anatomy is a characteristic feature of:

  1. C_3 plants
  2. C_4 plants
  3. CAM plants
  4. All of these
✅ View Answer & Explanation

Correct Answer: (2) C_4 plants
Explanation: Kranz anatomy involves large bundle sheath cells arranged like a wreath around the vascular bundles in C_4 plants like Maize and Sorghum.

Q6. In C_4 plants, the primary CO_2 acceptor is:

  1. RuBP
  2. PEP
  3. PGA
  4. OAA
✅ View Answer & Explanation

Correct Answer: (2) Phosphoenolpyruvate (PEP)
Explanation: PEP is a 3-carbon molecule present in the mesophyll cells of C_4 plants. RuBP is the primary acceptor in C_3 plants.

Q7. The enzyme responsible for primary carboxylation in C_3 plants is:

  1. PEP carboxylase
  2. RuBisCO
  3. NADP reductase
  4. ATP synthase
✅ View Answer & Explanation

Correct Answer: (2) RuBisCO
Explanation: RuBP carboxylase-oxygenase (RuBisCO) catalyzes the carboxylation of RuBP in the Calvin cycle.

Q8. Water splitting complex is associated with:

  1. PS I
  2. PS II
  3. ATP synthase
  4. Stroma lamellae
✅ View Answer & Explanation

Correct Answer: (2) PS II
Explanation: The water-splitting complex (Oxygen Evolving Complex) is located on the inner side of the thylakoid membrane and is physically associated with PS II.

Q9. Cyclic photophosphorylation results in the formation of:

  1. ATP and NADPH + H+
  2. ATP only
  3. NADPH + H+ only
  4. ATP, NADPH + H+ and O_2
✅ View Answer & Explanation

Correct Answer: (2) ATP only
Explanation: Cyclic flow only involves PS I and generates ATP. It lacks PS II, so no water splitting (O_2) or NADP reduction occurs.

Q10. How many turns of the Calvin cycle are required to produce one molecule of glucose?

  1. 1
  2. 3
  3. 6
  4. 12
✅ View Answer & Explanation

Correct Answer: (3) 6
Explanation: For every CO_2 molecule entering the cycle, 3 ATP and 2 NADPH are required. To make one 6-carbon glucose, 6 cycles are needed.

Q11. Photorespiration is a wasteful process because:

  1. There is no synthesis of ATP or NADPH
  2. It results in the release of CO_2 with the utilization of ATP
  3. It occurs only in C_3 plants
  4. All of the above
✅ View Answer & Explanation

Correct Answer: (4) All of the above
Explanation: Photorespiration wastes energy and fixed carbon without producing sugar or ATP.

Q12. Bundle sheath cells of C_4 plants are rich in which enzyme?

  1. PEP case
  2. RuBisCO
  3. Carbonic anhydrase
  4. Malate dehydrogenase
✅ View Answer & Explanation

Correct Answer: (2) RuBisCO
Explanation: Mesophyll cells of C_4 plants have PEPcase but lack RuBisCO. Bundle sheath cells lack PEPcase but are rich in RuBisCO.

Q13. Blackman’s Law of Limiting Factors is applied to:

  1. Respiration
  2. Transpiration
  3. Photosynthesis
  4. Growth
✅ View Answer & Explanation

Correct Answer: (3) Photosynthesis
Explanation: If a chemical process is affected by more than one factor, then its rate will be determined by the factor which is nearest to its minimal value.

Q14. What is the location of light and dark reactions respectively?

  1. Stroma and Grana
  2. Grana and Stroma
  3. Thylakoid and Lumen
  4. Cytoplasm and Mitochondria
✅ View Answer & Explanation

Correct Answer: (2) Grana and Stroma
Explanation: Light-driven reactions (photochemical phase) occur in the thylakoid/grana. Dark reactions (biosynthetic phase) occur in the stroma.

Q15. Non-cyclic photophosphorylation is also known as:

  1. Calvin Cycle
  2. Hatch-Slack Pathway
  3. Z-scheme
  4. Krebs Cycle
✅ View Answer & Explanation

Correct Answer: (3) Z-scheme
Explanation: It is called the Z-scheme due to its characteristic shape when the carriers are placed in order on a redox potential scale.

Q16. Accessory pigments include:

  1. Chlorophyll b
  2. Xanthophylls
  3. Carotenoids
  4. All of these
✅ View Answer & Explanation

Correct Answer: (4) All of these
Explanation: These pigments protect chlorophyll a from photo-oxidation and widen the spectrum of light absorbed for photosynthesis.

Q17. The biosynthetic phase of photosynthesis depends on:

  1. Direct presence of light
  2. Products of light reaction (ATP & NADPH)
  3. O_2 concentration
  4. Soil moisture only
✅ View Answer & Explanation

Correct Answer: (2) Products of light reaction (ATP & NADPH)
Explanation: Though called “dark” reaction, it is indirectly dependent on light as it requires the assimilatory power generated during the light phase.

Q18. Regeneration of which molecule is crucial for the Calvin cycle to continue uninterrupted?

  1. PGA
  2. RuBP
  3. Glucose
  4. Triose phosphate
✅ View Answer & Explanation

Correct Answer: (2) RuBP
Explanation: The regeneration of the CO_2 acceptor RuBP requires one ATP for every phosphorylation to form RuBP.

Q19. C_4 plants are special because:

  1. They can tolerate high temperatures
  2. They show a response to high light intensities
  3. They lack photorespiration
  4. All of the above
✅ View Answer & Explanation

Correct Answer: (4) All of the above
Explanation: Due to the CO_2 concentrating mechanism, C_4 plants avoid photorespiration and are highly productive in tropical climates.

Q20. The CO_2 compensation point for C_3 plants is approximately:

  1. 0-10 ppm
  2. 25-100 ppm
  3. 300-400 ppm
  4. 600 ppm
✅ View Answer & Explanation

Correct Answer: (2) 25-100 ppm
Explanation: C_3 plants have a higher compensation point than C_4 plants (0-10 ppm) because they are less efficient at low CO_2 levels.

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