Biology

Photosynthesis in Plants

1,492 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

Cholodny-Went Theory is related to

  1. photomorphogenesis

  2. photoperiodism

  3. phototropism

  4. photorespiration
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cholodny-Went Theory explains phototropism (bending toward light) through unequal auxin distribution - more auxin accumulates on the shaded side causing cells to elongate more. Photomorphogenesis is light-mediated development, photoperiodism is response to day length, and photorespiration is a wasteful process in C3 plants.

Multiple choice

The first compound that accepts CO2 during dark phase is

  1. NADP

  2. Ferrodoxin

  3. RUBP

  4. Cytochrome
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

RuBP (Ribulose-1,5-bisphosphate) is the first compound to accept CO2 in the Calvin cycle (dark phase of photosynthesis). This reaction is catalyzed by RuBisCO enzyme. NADP and Ferredoxin are involved in electron transport, while Cytochrome is part of electron transport chain.

Multiple choice

The molecular formula of Chlorophyll ‘a’ is

  1. C55H72O5N4Mg

  2. C55H70O6N4Mg

  3. C55H72O6N4Mg

  4. C50H72O5N4Mg
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Chlorophyll 'a' has the molecular formula C55H72O5N4Mg, containing a porphyrin ring with a magnesium atom at the center. Chlorophyll 'b' differs by having one more oxygen atom (C55H70O6N4Mg). The key difference is the substitution of a formyl group (-CHO) for the methyl group (-CH3) on the porphyrin ring.

Multiple choice

Identify the false statement.

  1. Leucoplast’s function is the removing of dead and worn out cellular organelles.

  2. Mitochondria help in the transport of ATP.

  3. Chloroplasts are the largest organelles of the plant cell in the cytoplasm.

  4. A function of chloroplast is the decomposition of water and liberation of oxygen to purify atmosphere.

  5. The synthesis of melanin occurs in golgi complex.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Leucoplasts are primarily organelles in which materials such as starch, oils and protein granules are stored. Lysosomes help in removing dead and worn out cellular organelles (cell debris) by digesting them.

Multiple choice

Which one of the following is the process involved in photosynthesis?

  1. Potential energy is released to form free energy.

  2. Free energy is converted into potential energy and stored.

  3. Food is oxidised to release carbon dioxide and water.

  4. Oxygen is taken, and carbon dioxide and water vapour are given out.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Free energy is converted into potential energy and stored.

Multiple choice

A plant is grown in bright sunlight. After a few hours, a leaf of the plant is plucked and treated with iodine solution and it turns black. When a section of this leaf is made and observed under microscope, _________ will be seen as stained blue-black.

  1. nucleus

  2. cell wall

  3. chloroplast

  4. vacuole

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

They are the food producers of the cell and they work to convert light energy of the sun into sugars that can be used by cells.

Multiple choice

The thylakoids are removed and kept in a culture medium containing carbon dioxide and water. If the set up is exposed to light, hexose sugars are not formed. An appropriate reason for this can be

  1. the light trapping device is not functional

  2. enzymes needed are not available

  3. no integrated functioning of the two photosystems

  4. carbon assimilation cannot take place in light

  5. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This is true as enzymes needed for the fixation of carbohydrates are not present in the above set up.

Multiple choice

During cyclic photophosphorylation

  1. light of wavelengths more than 680 nm is utilised

  2. no photolysis of water occurs

  3. shortage of oxidised NADPH is present

  4. neither O2 nor NADPH is produced

  5. all of the above
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

All of the above four statements are the true characteristics of cyclic photophosphorylation.

Multiple choice

Which of the types of chlorophyll molecules is found in all groups of algae?

  1. Chlorophyll-c

  2. Chlorophyll-d

  3. Chlorophyll-b

  4. Chlorophyll-a
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Chlorophyll-a is found in all groups of algae and is the universal photosynthetic pigment. It's the primary reaction center pigment in all photosynthetic organisms. Chlorophyll-b is found in green algae and plants, chlorophyll-c in diatoms and brown algae, and chlorophyll-d in some red algae - but only chlorophyll-a is truly universal across all algal groups.

Multiple choice

The acceptor of CO2, in CAMplants, is

  1. phosphoglyceric acid

  2. phosphoenol pyruvic acid

  3. ribulose biphosphate

  4. oxalo acetic acid
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In CAM (Crassulacean Acid Metabolism) plants, phosphoenol pyruvic acid (PEP) is the primary CO2 acceptor. During the night, PEP carboxylase fixes CO2 into oxaloacetate (which is converted to malate). During the day, malate releases CO2 for the Calvin cycle. Phosphoenol pyruvate is the 3-carbon compound that accepts CO2, not ribulose biphosphate (RuBP - used in C3 and C4 plants) or the other options listed.

Multiple choice

The absorption spectrum of chlorophyll

  1. explains why chlorophyll is a green pigment

  2. approximates the action spectrum of photosynthesis

  3. shows that some colours of light are absorbed more than others

  4. All of the above are correct
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The absorption spectrum of chlorophyll is useful in identifying the green colour pigment of chlorophyll. It approximates the action spectrum of photosynthesis. It also shows that some colours of light are absorbed more than others