Question 1

One scientist cultured Cladophora in a suspension of Azotobacter and illuminated the culture by splitting light through a prism. He observed that bacteria accumulated mainly in the region of:

Accepted Answer

Blue and red light. In Engelmann’s experiment, aerobic bacteria moved toward parts of the algal filament releasing the most oxygen. Chlorophyll absorbs blue and red light most effectively, so photosynthesis and oxygen release were greatest there.

Question 2

Stroma in the chloroplasts of higher plant contains:

Accepted Answer

light-independent reaction enzymes. The stroma contains the enzymes for the light-independent reactions (Calvin cycle), which use ATP and NADPH to fix carbon dioxide into sugars. Light-dependent reaction enzymes and chlorophyll are associated with the thylakoid membranes instead.

Question 3

In plant cells, peroxisomes are associated with

Accepted Answer

photorespiration. Peroxisomes are key organelles in photorespiration, where they help metabolize glycolate produced when RuBisCO acts as an oxygenase. This process occurs in light and is linked to chloroplasts and mitochondria, but it is not photosynthesis itself.

Question 4

Water vapour comes out from the plant leaf through the stomatal opening. Through the same stomatal opening carbon dioxide diffuses into the plant during photosynthesis. Reason out the above statements using one of following options.

Accepted Answer

Both processes can happen together because there is no competition between water and CO2.. Both water vapour and carbon dioxide can diffuse through the same stomatal pore at the same time. Their movement is driven by different concentration gradients, so one does not prevent the other from passing.

Question 5

Which one of the following is essential for photolysis of water?

Accepted Answer

Manganese. Manganese is a key component of the oxygen-evolving complex in photosystem II, where it participates directly in the photolysis of water. Without manganese, the light-driven splitting of water and release of oxygen cannot proceed normally.

Question 6

Oxygen is not produced during photosynthesis by

Accepted Answer

Green sulphur bacteria. Green sulphur bacteria carry out anoxygenic photosynthesis, using compounds like hydrogen sulfide rather than water, so they do not release oxygen. The other options are oxygenic photosynthesizers and do produce oxygen.

Question 7

In a chloroplast the highest number of protons are found in

Accepted Answer

lumen of thylakoids. During the light reactions, the photosynthetic electron transport chain pumps protons from the stroma into the thylakoid lumen, and water splitting also adds protons there. This makes the thylakoid lumen the compartment with the highest proton concentration.

Question 8

Suppose an aquatic plant is placed in a test tube containing distilled water and the tube is stoppered. The tube is left outdoors for 24 hours and the pH value of the water is then measured at regular intervals. Which of the following is the most probable result?

Accepted Answer

pH of water will increase. In daylight, the aquatic plant photosynthesizes and uses up dissolved carbon dioxide. Since CO2 forms carbonic acid in water, removing it makes the water less acidic, so the pH rises. In a stoppered tube, this effect is most likely to dominate over 24 hours outdoors.

Question 9

The core metal of chlorophyll is

Accepted Answer

magnesium. Chlorophyll molecules contain a porphyrin-like ring with a central metal ion that is essential for light absorption. In plants, that central metal is magnesium, not iron or the other listed metals.

Question 10

Photosynthesis in C4 plants is relatively less limited by atmospheric CO2 levels because of:

Accepted Answer

The primary fixation of CO2 is mediated via PEP carboxylase.. C4 plants first fix CO2 with PEP carboxylase, an enzyme with high affinity for CO2 and no oxygenase activity. This reduces dependence on atmospheric CO2 and helps concentrate CO2 around Rubisco.

Question 11

Which fractions of the visible spectrum of solar radiations are primarily absorbed by carotenoids of the higher plants?

Accepted Answer

Violet and blue. Carotenoids in higher plants absorb mainly in the short-wavelength region of visible light, especially violet and blue. This helps them transfer energy to chlorophyll and protect the photosynthetic apparatus from excess light.

Question 12

At a temperature above 35°C:

Accepted Answer

rate of photosynthesis will decline earlier than that of respiration. Photosynthesis is more sensitive to high temperatures because its enzymes and chlorophyll-related reactions are easily disrupted above the optimum. Respiration generally tolerates higher temperatures for longer, so its rate declines later than photosynthesis.

Question 13

Plants adapted to low light intensity have:

Accepted Answer

larger photosynthetic unit size than the sun plants. Plants adapted to low light need to absorb as much available light as possible, so they have larger photosynthetic units with more antenna pigments per reaction center. Sun plants usually have smaller units because light is abundant.

Question 14

Protochlorophyll differs from chlorophyll in lacking:

Accepted Answer

2 hydrogen atoms in one of its pyrrole rings. Protochlorophyll differs from chlorophyll by having one less reduced pyrrole ring. That means it lacks 2 hydrogen atoms in one pyrrole ring, which changes the ring from a more saturated to a less saturated form.

Question 15

Which of the following absorb light energy for photosynthesis?

Accepted Answer

Chlorophyll. Chlorophyll is the main light-absorbing pigment in photosynthesis. It captures light energy and uses it to drive the reactions that convert carbon dioxide and water into sugars.

Question 16

Most plants are green in colour because:

Accepted Answer

chlorophyll is least effective in absorbing green light. Chlorophyll absorbs red and blue light much more strongly than green light. Because green light is absorbed least, it is mostly reflected, making plants appear green.

Question 17

Maximum solar energy is trapped by:

Accepted Answer

growing algae in tanks. Algae have a very high photosynthetic efficiency and a large surface area-to-volume ratio, so they can capture more solar energy per unit area than land plants. Growing them in tanks also allows optimal control of light, nutrients, and carbon dioxide, maximizing energy capture.

Question 18

Chlorophyll ‘a’ molecule at its carbon atom 3 of the Pyrrole ring II has one of the following:

Accepted Answer

methyl group. Chlorophyll a has a methyl group at carbon 3 of pyrrole ring II. The aldehyde group is characteristic of chlorophyll b instead, so the correct choice is methyl.

Question 19

The principle of limiting factors was proposed by:

Accepted Answer

Blackman. Blackman proposed the principle of limiting factors, stating that when a process depends on several variables, its rate is limited by the factor in shortest supply or least favorable condition. This is a classic concept in photosynthesis and other biological processes.

Question 20

Nine-tenth of all photosynthesis of world (85-90%) is carried out by:

Accepted Answer

algae of the ocean. Most of the planet’s photosynthesis happens in the oceans because microscopic and other algae are extremely abundant and cover vast areas. They collectively contribute the majority of global oxygen production and carbon fixation.

NEET Biology: Photosynthesis in Higher Plants questions with solutions

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