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

Why are plants green?

  1. They absorb only green wavelengths of light.

  2. They absorb only yellow and blue wavelengths of light.

  3. They reflect nearly all wavelengths of light.

  4. They reflect green wavelengths of light.

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

Plants appear green because chlorophyll pigments absorb red and blue light efficiently but reflect green wavelengths, which then reach our eyes.

Multiple choice

Which statement is not true about the cyclic electron pathway?

  1. It produces ATP.

  2. It involves Photosystem I.

  3. It produces NADPH.

  4. It is believed to be the first of the two electron transport pathways.

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

The cyclic electron pathway involves Photosystem I and produces ATP, but it does not involve the reduction of NADP+ to NADPH, which occurs in the noncyclic pathway.

Multiple choice

Which of the following options is most closely associated with the process of electron transport?

  1. A stack of thylakoid membrane structures

  2. A flattened disk or sac in the chloroplast

  3. The double membrane of the chloroplasts

  4. The cytochrome system in the membranes of the thylakoids

  5. A central fluid filled space in the chloroplast

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The cytochrome system is a series of protein complexes embedded in the thylakoid membrane that facilitates electron transfer during the light reactions.

Multiple choice

Which statement is not true about photosystems?

  1. Photosystem I passes electron on to photosystem II.

  2. Each photosystem contains numerous pigment molecules that act as antennas to capture light.

  3. Photosystem I contains a reaction center molecule that absorbs light best around 700 nm, so it is called P700.

  4. Electrons in the reaction center molecule are excited by absorbing photons of light and are passed along to an acceptor molecule.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the noncyclic pathway, electrons flow from Photosystem II to Photosystem I, not the other way around. Photosystem II is the first in the chain.

Multiple choice

The end product of the Calvin cycle is ________.

  1. ATP

  2. ribulose bisphosphate (RuBP)

  3. phosphoglyceraldehyde (PGAL)

  4. PEP carboxylase (PEPcase)

  5. Carbon dioxide
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Calvin cycle uses ATP and NADPH to fix carbon dioxide into G3P (phosphoglyceraldehyde), which is often referred to as PGAL.

Multiple choice

Which statement is not true about the noncyclic electron pathway?

  1. It absorbs photons in Photosystem I.

  2. It absorbs photons in Photosystem II.

  3. It produces ATP.

  4. It produces NADPH.

  5. It produces carbohydrates through carbon dioxide fixation.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The noncyclic electron pathway produces ATP and NADPH, but the actual production of carbohydrates occurs in the Calvin cycle, which is a separate stage from the light-dependent electron transport.

Multiple choice

Protons (H+) accumulate in the thylakoid space during electron transport between photosystem I and II. The extra protons in the thylakoid space ___________________.

  1. enter the photorespiration pathway

  2. convert NADP to NADPH and generate ATP in the process

  3. are small enough to diffuse back out through the lipid bilayer

  4. raise the pH of the space until the processes stop

  5. move from the thylakoid space to the stroma through an ATP synthase complex channel that generates ATP
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice

Which of the following options is the most closely associated with the Calvin cycle?

  1. ATP production

  2. Production of oxygen

  3. Carbon dioxide fixation

  4. Carbon dioxide production

  5. Removal of electrons from water for passage through an electron transport system

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Calvin cycle is the light-independent reaction phase of photosynthesis responsible for fixing atmospheric carbon dioxide into organic molecules.

Multiple choice

Which of the following statements is not true about photosynthesis?

  1. In the non-cyclic photophosphorylation, water is split and oxygen is released.

  2. Photosystem II makes non-cyclic photophosphorylation more efficient than does cyclic photophosphorylation.

  3. The cyclic system is used when there is insufficient NADP+ to absorb electrons in plants cells.

  4. More carbohydrate is produced during cyclic photophosphorylation than during non-cyclic photophosphorylation.

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

Cyclic photophosphorylation produces ATP but does not produce carbohydrates, as it lacks the Calvin cycle integration and NADPH production associated with non-cyclic pathways.

Multiple choice

Which of the following statements is/are false?

a. Carbon dioxide is absorbed from the atmosphere by the leaves through minute pores called stomata. b. The food produced by plants through photosynthesis is in the form of sugars. c. As animals cannot prepare their own food, they are called autotrophs.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This is the correct option as this statement is false. As animals cannot prepare their own food, they are called heterotrophs.

Multiple choice

Which of the following processes take place in desert plants?

a. They take up CO2 at night. b. They absorb sunlight in the day and prepare starch at the night. c. Intermediates are prepared at night. d. Stems carry out photosynthesis. e. They store the light energy during the day.

  1. Only a, c and e

  2. Only a and b

  3. Only b and e

  4. Only a, c and d
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

a, c and d are the processes carried out by the desert plants. They take up CO2 at night. Intermediates are prepared at night. Stems carry out photosynthesis.