NEET Biology Photosynthesis in Higher Plants MCQs Set 16

Answer: (c) CO₂ combines with PEP

Explanation:
1. The C4 pathway begins with CO2 combining with PEP.
2. This gives oxaloacetic acid, a C4 compound.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (a) 6

Explanation:
1. Regeneration of RuBP uses one ATP per RuBP, so 6 ATP per glucose.
2. Reduction of 12 PGA needs 12 ATP, giving 18 in total.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (b) ¹⁴C and ¹⁸O

Explanation:
1. Carbon-14 and oxygen-18 are used for studying photosynthesis.
2. S-35 and P-32 are used for protein and DNA labelling.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (b) C₄ plants

Explanation:
1. C4 plants have chloroplasts in the bundle sheath cells.
2. C3 plants lack them there.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (b) Bundle sheath cells

Explanation:
1. In C4 plants RuBP accepts CO2 in the bundle sheath cells.
2. PEP carboxylase works in the mesophyll cells.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (a) Large & agranal

Explanation:
1. The bundle sheath chloroplasts of C4 plants are large and agranal.
2. They lack PS II, so no water splitting occurs there.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (c) C₄ plants

Explanation:
1. C4 plants have high photosynthetic efficiency and bundle sheath chloroplasts.
2. C3 plants lack both.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (b) 12

Explanation:
1. Making one hexose needs 12 molecules of water.
2. They supply the hydrogen for 12 NADPH.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (c) Six cycles

Explanation:
1. Each cycle fixes one CO2, so six cycles are needed for one hexose.
2. Hence 6 CO2 gives 6 turns.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (c) 3-C and 4-C compounds

Explanation:
1. The first stable product of the Calvin cycle is a 3C compound, PGA.
2. The Hatch and Slack cycle gives a 4C compound, OAA.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (d) Chlorella

Explanation:
1. Calvin used the green alga Chlorella (and Scenedesmus).
2. Spirogyra, Volvox and Chlamydomonas were not used.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (a) Light duration

Explanation:
1. The rate depends on light intensity, quality and temperature.
2. It does not depend on the duration of light, which only decides how long photosynthesis runs.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (c) Destruction of chlorophyll

Explanation:
1. Solarisation is destruction of chlorophyll in strong light.
2. It reduces photosynthesis.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (d) Phosphoglycolate

Explanation:
1. In photorespiration RuBP binds O2 to give phosphoglycolate and PGA.
2. Phosphoglycolate is the first product.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (a) 10 : 1

Explanation:
1. In daylight photosynthesis is about 10 times faster than respiration.
2. So the ratio of O2 produced to O2 consumed is about 10 : 1.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (b) These plants obtain CO₂ from water in the form of HCO₃⁻.

Explanation:
1. Submerged hydrophytes use bicarbonate dissolved in water.
2. So atmospheric CO2 is not limiting.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (a) Glycolate cycle

Explanation:
1. The C2 cycle is the glycolate pathway of photorespiration.
2. Glycolate is a two carbon molecule.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (c) Synthesis of ATP

Explanation:
1. Photorespiration neither makes ATP nor NADPH.
2. It uses O2, releases CO2 and uses ATP.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (c) CO₂

Explanation:
1. On a clear sunny day CO2 is the limiting factor.
2. On cloudy days or under shade light becomes limiting.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (c) It is a characteristic of C₄ plants

Explanation:
1. Photorespiration is a feature of C3 plants.
2. C4 plants avoid it, so the statement that it is a characteristic of C4 plants is wrong.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (a) 400–700 nm

Explanation:
1. PAR is 400 to 700 nm.
2. This is the visible range.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (d) 3–phosphoglyceric acid

Explanation:
1. The first stable product of the C3 cycle is 3-phosphoglyceric acid.
2. Malic and oxaloacetic acids are C4 products.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.

Answer: (a) C₃ plant-maize

Explanation:
1. Maize is a C4 plant, not a C3 plant.
2. The other pairs are correct.

Teacher's Note:
1. Photosynthesis questions follow a fixed chain: light reaction in thylakoids, dark reaction in stroma.
2. Link each fact to its site, its enzyme or its scientist to remember it.