In photorespiration, glycolate is converted into serine and carbon dioxide in:

  • Mitochondria

  • Cholorplasts

  • Vacuoles

  • Peroxisomes

In the C4 pathway, which of the following molecules combines with carbon dioxide?

  • glyceraldehyde phosphate

  • ribulose biphosphate

  • phosphoenol pyruvic acid

  • citric acid

Dark reactions of photosynthesis are actually not totally independent of light as:

  • The initial reactions occur in the presence of light.

  • The reaction will be inhibited by the presence of light.

  • They can occur during the day as well.

  • They utilize the products of the light reaction.

All the following regarding the role of xanthophylls and carotenoids in photosynthesis are correct except:

  • They act as accessory pigments

  • Their peak absorption is in blue and red regions of VIBGYOR

  • They enable a wider range of wavelength of incoming light to be utilized for photosynthesis

  • They protect chlorophyll a form of photo-oxidation.

Which stage of the Calvin Cycle utilizes ATP?

  • Carboxylation

  • Reduction

  • Regeneration

  • Both 2 and 3

Compared to retinal, chlorophyll can be described as a pigment that has a 

  • narrow absorption range but high efficiency

  • narrow apsorption range but low efficiency

  • wide absorption range but high effeciency

  • wide absorption range but low efficiency

Consider the situation where photosynthesis is going on at a steady pace in a typical experiment with a light on, and carbon dioxide is being combined with ribulose-bisphosphate (RuBP) to produce 3-phosphoglycerate (3PG). Then suddenly the source of carbon dioxide is eliminated. What changes in the concentrations of 3PG and RuBP would occur?

  • 3PG levels rise, RuBP levels fall.

  • 3PG levels fall, RuBP levels rise.

  • 3PG levels rise, RuBP levels rise.

  • 3PG levels fall, RuBP levels fall.

Identify the statement that is true for C4 plants but not for C3 plants?

  • Initially fix carbon dioxide in mesophyll cells as 4-carbon long compounds.

  • Initially fix carbon dioxide in bundle sheath cells as 3-carbon long compounds.

  • Initially fix carbon dioxide in mesophyll cells as 3-carbon long compounds.

  • Initially fix carbon dioxide in bundle sheath cells as 4-carbon long compounds.

Crops such as tomatoes and bell pepper, allowed to grow in a carbon dioxide rich environment, show higher yields because:

  • They show an increased rate of photosynthesis at higher carbon dioxide concentrations

  • They can respond to high carbon dioxide conditions even in low light conditions.

  • They show C4 pathway for cabon fixation at high carbon dioxide is the limiting factor in such plants. 

  • Only carbon dioxide is the limiting factor in such plants

At about what percentage of the full sunlight does light saturation occurs in photosynthesis?

  • 10

  • 25

  • 70

  • 95

Suppose the interoir of the thylakoids of isolated chloroplasts and then transferred in the dark to a pH 8 solution. What would be likely to happen?

  • The isolated chloroplasts will make ATP

  • The Clavin cycle will be activated.

  • The cyclic photophosphorylation will occur

  • Isolated chloroplasts will generate oxygen gas

Consider the following two statements:

I. Except for plants in shade or in dense forests, light is rarely a limiting factor in nature for photosynthesis.

II. Light saturation occurs at 50% of the full sunlight.

  • Both statements are correct and II explains I

  • Both statements are incorrect

  • I is correct and II is incorrect

  • I is incorrect and II is correct

For assimilation of one CO2 molecule via photosynthesis, the energy required in form of ATP and NADPH2 are:

  •  2 ATP and 2 NADPH2 

  • 5 ATP and 3 NADPH2 

  • 3 ATP and 2 NADPH2 

  • 18 ATP and 12 NADPH2. 

Phosphoenol pyruvate (PEP) is the primary CO2 acceptor in

  • C3 -plants 

  • C4 -plants

  • C2 -plants

  • C3 and C4 -plants

With reference to factors affecting the rate of photosynthesis, which of the following statements is not correct?

  • Light saturation for CO2-fixation occurs at 10% of full sunlight.

  • Increasing atmospheric CO2 concentration upto 0.05% can enhance the CO2-fixation rate

  • C3 plants respond to higher temperature with enhanced photosynthesis, while C4 plants have a much lower temperature optimum.

  • Tomato is a greenhouse crop, which can be grown in a CO2-enriched atmosphere for higher yield. 

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 the following options. 

  • Both process can happen together because the diffusion coefficient of water and CO2 is different. 

  • The above processes happen only during night time

  • One process occurs during the day time and the other night

  • Both processes cannot happen simultaneously

A plant in your garden avoids photorespiratory losses, has improved water use efficiency, shows high rates of photosynthesis at high temperatures and has improved efficiency of nitrogen utilization. In which of the following physiological groups would you assign this plant?

  • C4

  • CAM

  • Nitrogen-fixer

  • C3

Emerson's enhancement effect and red drop have been instrumental in the discovery of 

  • two photosystems operating simultaneously

  • photophosphorylation and cyclic electron transport. 

  • Oxidative phosphorylation

  • photophosphorylation and non-cyclic electron transport

In a chloroplast the highest number of protons are found in

  • lumen of thylakoids

  • inter membrane space

  • antenna complex

  • Stroma

In photosynthesis, the light-independent reactions take place at 

  • thylakoid lumen 

  • photosystem l

  • photosystem ll

  • stromal matrix

Anoxygenic photosynthesis is characteristic of 

  • Rhodospirillum

  • Spirogyra

  • Chlamydomonas 

  • Ulva

The correct sequence of cell organelles during photorespiration is 

 

  • chloroplast-Golgi bodies-mitochondria

  •  chloroplast-rough endoplasmic reticulum-dictyosomes

  •  chloroplast-peroxisome-mitochondria

  •  chloroplast-vacuole-peroxisome

PGA as the frist CO2 fixation was discovered in photosynthesis of 

  • bryophyte

  • gymnosperm

  • angiosperm

  • algae

C4 -plants are more efficient in photosynthesis than C3 -plants due to 

  • higher leaf area

  • presence of larger number of chloroplasts in the leaf cells. 

  • presence of thin cuticle

  • lower rate of photorespiration

THe C4 -plants are photosynthetically more efficient than C3 -plants because

  • the CO2 compensation point is more

  • CO2 generated during photorespiration is trapped and recycled through PEP carboxylase

  • the CO2 efflux is not prevented

  • they have more chloroplasts.

Electrons from excited chlorophyll molecule of photosystem-II are accepted first by

  • cytochrome-b

  • cytochrome-f

  • quinone

  • ferredoxin

In the leaves of C4 -plants malic acid synthesis during CO2 fixation occurs in 

  • epidermal cells

  • mesophyll cells

  • bundle sheath

  • guard cells

The wavelength of light abosorbed by Pr form of phytochrome is :

  • 640 nm

  • 680 nm

  • 720 nm

  • 620 nm

In photosystem-I, the first electron acceptor is :

  • ferredoxin

  • cytochrome

  • plastocyanin

  • an iron-sulphur protein

During photorespiration, the oxygen consuming reaction(s) occur in :

  • stroma of chloroplasts and mitochondria

  • stroma of chloroplasts and peroxisomes

  • grana of chloroplasts and peroxisomes

  • stroma of chloroplasts

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Practice Botany Quiz Questions and Answers