NEET Biology Photosynthesis in Higher Plants MCQs Set 14

Answer: (b) Water

Explanation:
1. The oxygen released comes from water, shown by O-18 labelling.
2. CO2 supplies the carbon and oxygen that end up in the sugar.

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) Photosynthesis

Explanation:
1. Photosynthesis traps light and stores it as the chemical energy of sugars.
2. Digestion, respiration and fermentation release chemical energy instead.

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) Blackman

Explanation:
1. Blackman proposed the law of limiting factors in 1905.
2. Calvin and Hill worked on the dark and light reactions.

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) 1-2%

Explanation:
1. Higher plants use only about 1 to 2 percent of the incident light energy.
2. The rest is reflected, transmitted or lost as heat.

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) The plants would thrive well

Explanation:
1. 300 ppm is 0.03 percent, which is about the normal atmospheric level.
2. CO2 is the main limiting factor, so plants thrive and even do better with more CO2, up to about 0.05 percent.

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

Explanation:
1. Radioactive carbon-14 labels CO2 so its path can be followed.
2. Calvin used it to work out the dark reaction.

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) All of the above.

Explanation:
1. All three observations support the water origin of oxygen.
2. O-18 in water appears in O2, the Hill reaction releases O2 without CO2, and bacteria using H2S give sulphur instead of O2.

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) ¹⁴CO₂

Explanation:
1. The path of carbon was traced with radioactive carbon-14 in CO2.
2. O-18 follows oxygen and P-32 follows phosphate.

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) 1%

Explanation:
1. Only about 1 percent of the water absorbed is used in photosynthesis.
2. Most is lost in transpiration.

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) Carbon dioxide is essential for photosynthesis

Explanation:
1. Moll's half leaf experiment keeps one half of a leaf in a jar with KOH and the other half in air.
2. The half without CO2 gives no starch, so CO2 is necessary.

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) Engelmann

Explanation:
1. Engelmann used the alga Cladophora and aerobic bacteria.
2. Bacteria gathered in blue and red light, giving the action spectrum.

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) Redox-reaction, endergonic, anabolic

Explanation:
1. Photosynthesis is a redox process that needs energy and builds sugar.
2. So it is endergonic and anabolic, with water oxidised and CO2 reduced.

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) Ingenhousz

Explanation:
1. Ingenhousz showed that sunlight and the green parts of a plant are needed for purifying air.
2. Priestley only showed that plants restore air.

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) Chloroplast

Explanation:
1. Photophosphorylation is the light driven ATP synthesis.
2. It occurs in the thylakoids of the chloroplast.

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) Anthocyanin

Explanation:
1. Anthocyanin is a vacuolar pigment.
2. Carotene, xanthophyll and chlorophyll b are chloroplast pigments.

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) Stroma

Explanation:
1. The dark reaction (Calvin cycle) takes place in the stroma.
2. The enzymes for CO2 fixation are in the stroma.

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) In the grana of chloroplasts

Explanation:
1. Chlorophyll is located in the thylakoid membranes.
2. Thylakoids are stacked into grana, so chlorophyll is in the grana of chloroplasts.

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) Blue light

Explanation:
1. Chlorophyll a has its highest absorption peak in the blue region and a second peak in the red region.
2. Green light is reflected and yellow is absorbed very little.

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) Protecting chlorophyll molecules from photooxidation

Explanation:
1. Carotenoids are accessory pigments.
2. They absorb excess light and protect chlorophyll from photooxidation.

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) P-700

Explanation:
1. The reaction centre of PS I is P700.
2. The reaction centre of PS II is P680.

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) Porphyrin system

Explanation:
1. All chlorophylls have a tetrapyrrole porphyrin ring with Mg.
2. The other options are electron carriers.

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) Centre of porphyrin ring

Explanation:
1. Magnesium is bound in the centre of the porphyrin ring.
2. The phytol tail is a long hydrophobic chain without Mg.

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) Chl-'a'

Explanation:
1. Chlorophyll a is present in all photosynthetic organisms except bacteria.
2. It is therefore called the universal photosynthetic pigment.

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) Lumen surface of thylakoid membrane

Explanation:
1. Photolysis of water occurs on the lumen side of the thylakoid membrane.
2. It is linked to PS II and the oxygen evolving complex.

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.