Biology

Photosynthesis in Plants

1,508 Questions

Photosynthesis is the biological process by which plants convert light energy into chemical energy. This page contains practice questions covering essential topics like chlorophyll, light reactions, and the pathways specific to plants. This material is crucial for medical entrance exams and academic assessments.

Chlorophyll and pigmentsLight reactionsCalvin cycleCAM plantsElectron transportPhotosynthesis factors

Photosynthesis in Plants Questions

Multiple choice

Match the following: Medium of growth of plants|Function| |a. Water|1. It helps in releasing metabolic energy essential for growth activities.| |b. Oxygen|2. It is required by plants for the synthesis of protoplasm and it acts as a source of energy.| |c. Nutrient|3. It provides the medium for enzymatic activities that is needed for growth.|

  1. a - 3, b - 1, c - 2

  2. a - 2, b - 1, c - 3

  3. a - 1, b - 3, c - 2

  4. a - 1, b - 2, c - 3

  5. a - 3, b - 2, c - 1
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is the correct option. Water provides the medium for enzymatic activities that is needed for growth. Oxygen helps in releasing metabolic energy essential for growth activities. Nutrient is required by plants for the synthesis of protoplasm and it acts as a source of energy.

Multiple choice

Why do leaves look green in colour?

  1. Due to presence of carbon dioxide

  2. Due to chlorofluorocarbons

  3. Due to chlorophyll

  4. Due to plants planted in soil

  5. Due to sunlight
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Chlorophyll is the main agent responsible for green leaves.

Multiple choice

Respiration in plants

  1. results in the formation of vitamins

  2. is characteristic of all living cells

  3. often requires carbon dioxide

  4. occurs only during day
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Cellular respiration occurs in all living cells (plant and animal) as it's essential for energy production. In plants, respiration happens continuously, day and night, in mitochondria. While plants produce oxygen during photosynthesis (which only occurs in light), they simultaneously consume oxygen for respiration. Respiration never produces vitamins.

Multiple choice

Red drop and Emerson effect have proved the existence of

  1. Light and dark reactions in photosynthesis

  2. Two distinct photosystems in photosynthesis

  3. The supply of electrons from oxygen evolving complex

  4. Electron transport from water to NADP+ across thylakoids
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Red drop (decrease in photosynthetic efficiency at wavelengths >680 nm) and Emerson enhancement effect (greater than additive photosynthesis when beams of 680 nm and shorter wavelengths are combined) demonstrated existence of two photosystems working in series-PSII and PSI.

Multiple choice

Which of the following statements is not correct?

  1. The magnesium atom in chlorophyll a carries the electrons involved in photosynthesis.

  2. Cytochromes are intrinsic proteins of chloroplast's thylakoid membrane.

  3. Ferredoxin has a large positive redox potential and tends to accept electrons.

  4. The phytol tails of chlorophyll a and chlorophyll b are hydrophobic.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The correct answer is 2.

Multiple choice

With reference to photosynthesis, what is the CFO - CF1 complex?

  1. ATP synthetase

  2. Ferredoxin - NADP reductase

  3. Cytochrome b6/f complex

  4. RuBP carboxylase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The CF0-CF1 complex, also known as ATP synthase, is a multi-subunit protein complex embedded in the thylakoid membrane that synthesizes ATP from ADP and inorganic phosphate using the proton gradient generated during photosynthesis.

Multiple choice

With reference to photosynthesis, in chloroplasts, consider the following statements:

  1. The reactions that break down water and produce oxygen are located on the lumen side of the thylakoid membrane, in granum areas.
  2. The molecules of ferredoxin-NADP reductase that generate NADPH are located on the side of the membrane facing stroma. Which of the statements given above is/are correct ?

  1. 1 only

  2. 2 only

  3. Both 1 and 2

  4. Neither 1 nor 2
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Water-splitting and oxygen evolution occur on lumen side of thylakoid membrane within PSII complexes located in granal stacks. Ferredoxin-NADP reductase (producing NADPH) is bound to stroma-facing side of thylakoid membrane. Both statements correctly describe spatial organization.

Multiple choice

Which one of the following is the correct sequence of the appearance of intermediate compounds in the pathway of photorespiration ?

  1. Glyoxylate - glycine - glycolate - serine

  2. Glyoxylate - serine - glycolate - glycine

  3. Glycolate - glyoxylate - glycine - serine

  4. Glycolate - glyoxylate - serine - glycine
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Photorespiration begins when RuBP oxygenase produces phosphoglycolate, which is converted to glycolate. Glycolate exits chloroplasts, enters peroxisomes, and is converted to glyoxylate. Glyoxylate then transaminates to glycine. Glycine enters mitochondria, where two molecules combine to form serine, releasing CO2 and NH3. Thus the sequence is: Glycolate → glyoxylate → glycine → serine.

Multiple choice

Assertion (A) : Ferredoxin carries two electrons at a time. Reason (R) : The active site of ferredoxin consists of two iron atoms bound to two sulfur atoms

  1. Both A and R are individually true and R is the correct explanation of A

  2. Both A and R are individually true but R is not the correct explanation of A

  3. A is true but R is false

  4. A is false but R is true
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Ferredoxin is an iron-sulfur protein that typically transfers one electron at a time, making Assertion (A) false. However, Reason (R) is true because its active site contains iron-sulfur clusters (such as 2Fe-2S centers). Therefore, A is false and R is true.

Multiple choice

What are ATP and NADPH?

  1. Sources of light

  2. End products of photosynthesis

  3. Sources of infrared radiations

  4. Energy storage molecules

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Yes, it is correct. Light-dependent reactions or light reactions capture the energy of light and use it to make the energy-storage molecules ATP and NADPH.

Multiple choice

Which of the following statements is/are incorrect about photosynthesis? (a) It occurs in three stages. (b) Oxygen is produced using visible light. (c) Infrared light is also used by some organisms to produce oxygen. (d) Glucose is oxidised.

  1. a and d

  2. a, b and c

  3. b and c

  4. only d

  5. b, c and d
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Yes, it is the correct answer. Photosynthesis occurs in two stages. In cellular respiration, glucose and other compounds are oxidized to produce carbon dioxide, water and release chemical energy. Here carbon dioxide is converted into carbohydrate.

Multiple choice

Where is the aqueous fluid, stroma present?

  1. In the chloroplast

  2. In an intermembrane space between two phospholipid membranes of chloroplast

  3. In the thylakoids

  4. In the green pigment, chlorophyll

  5. Within the inner membrane
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The chloroplast is enclosed by a membrane. This membrane is composed of a phospholipid inner membrane, a phospholipid outer membrane, and an intermembrane space between them. Within the membrane is an aqueous fluid called the stroma.