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 biology protectors of biosphere structure of chloroplast plastids photosynthetic pigments

What percentage of water, proteins, lipids and pigments are present in chloroplasts respectively?

  1. 50, 25, 15 and 10

  2. 90, 5, 2 and 3

  3. 95, 2, 1 and 2

  4. 85, 10, 3 and 2
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The chloroplasts are composed of the carbohydrates, lipids, proteins, chlorophyll, carotenoids (carotene and xanthophylls), DNA, RNA and certain enzymes and co-enzymes. The chloroplasts also contain some metallic atoms as Fe, Cu, Mn and Zn. By chemical analysis, these consist of lipids and proteins basically. Lipids are mainly phospholipid components of the membranes and lamellae. Proteins also contain enzymes, which are fully present in mature plastids. By the chemical analysis, it is observed that chloroplastids contain 90% of water, 5% of proteins, 2% of lipids and 3% of pigments.

Multiple choice biology protectors of biosphere structure of chloroplast plastids photosynthetic pigments

Thylakoids possess photosynthetic units called

  1. Photosystem.

  2. Electron transport system.

  3. Photolysis complex.

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

Thylakoid is a sheet-like membrane-bound structure which is the site of the light-dependent photosynthesis reactions within the chloroplasts and cyanobacteria. Photosystems are then functional and structural units of protein complexes involved in photosynthesis.

The electron transport chain is a series of the proteins and organic molecules which are found in the inner membrane of the mitochondria. Photolysis is the chemical process by which molecules are broken down into smaller units through the absorption of light.

The synthesis of ATP in chloroplasts, promoted by light, is termed as photophosphorylation

So the correct option is A.

Multiple choice biology protectors of biosphere structure of chloroplast plastids photosynthetic pigments

Which pigment absorbs the red and far-red light?

  1. Cytochrome

  2. Phytochrome

  3. Carotenoids

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

Phytochrome is a light sensitive pigment in plants and some bacteria and fungi. It exists in two interconvertible forms- Pr and Pfr. Pfr absorbs far red light of 730 nm wavelength. When it absorbs far red light, it converts to its original form, Pr. Thus Pfr is the active form of phytochrome which inhibits flowering.

Multiple choice biology protectors of biosphere structure of chloroplast plastids photosynthetic pigments

Solarisation is a process in which

  1. Sugars are formed with the help of solar energy

  2. Chlorophyll is formed

  3. Destrution of chlorophyll and ultimate death of protoplasmic compounds occurs

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Chlorophyll pigments trap sunlight during the process of photosynthesis but get destroyed on exposure to light of higher intensity. An exposure to high light intensity for even a small duration can be harmful. The destruction of chlorophyll when exposed to light of high intensity is called as solarization. It occurs due to irreversible chemical changes in the structure of chlorophyll molecule.

Multiple choice biology protectors of biosphere structure of chloroplast plastids photosynthetic pigments

Photosynthetic units are referred as

  1. Quantasomes

  2. Oxysomes

  3. Phycobilisomes
  4. $F _{1}$ particles
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Photosynthetic units are referred as quantasomes. Quantasomes are particles found in the thylakoid membrane of chloroplasts in which photosynthesis takes place.

Oxysomes are the structures which are present on the surface of the folded inner membrane of the mitochondria. They are also called as f$ _0$-f$ _1$ particles or ATP synthase. They play an important role in the formation of energy for the functioning of the cell.
The protein complexes attached to thylakoid membranes are known as phycobilisomes. They are made up of phycobiliproteins and help in the transfer of light energy to chlorophyll-a molecule of photosystem-II.
Thus, the correct answer is option A. 

Multiple choice biology protectors of biosphere structure of chloroplast plastids photosynthetic pigments

Isotopes employed to study the process of photosynthesis reaction are

  1. $S^{68}\, and\, P^{32}$
  2. $C^{14}\, and\, O^{18}$
  3. $N^{14}\, and\, Co^{60}$
  4. $N^{14}\, and\, O^{18}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Photosynthesis is a redox reaction in which carbon dioxide is reduced to sugars in dark reaction and water is oxidised to release oxygen in light reaction of photosynthesis. $C^{14}$ label was used to trace the path of carbon in the dark reaction in $C _3$ plants by Calvin, Benson and Basham. The $O^{18}$ label was used by Rumen and Kamen to experimentally prove that the source of oxygen released during light reaction of photosynthesis is water.

Multiple choice biology protectors of biosphere structure of chloroplast plastids photosynthetic pigments

Phytochrome is found in

  1. Algae.

  2. Virus.

  3. Gymnosperms.

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

The main photoreceptor for photoperiodism and many other light initiated plant responses (such as germination and seedling establishment) is phytochrome. It is a family of about five blue-green pigment proteins, each of which is coded for by a different gene in higher plants, like angiosperms. 

Multiple choice biology protectors of biosphere structure of chloroplast plastids photosynthetic pigments

Which of the following is true about photosynthesis?

  1. Light driven

  2. Photo driven

  3. Anabolic

  4. Enzyme moderated

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

Option 'E' is true.

Photosynthesis is an anabolic endergonic and reductive process. Photosynthesis is a process of conversion of light energy into chemical energy. Light not only behaves as a wave but also has energy particles called photons which are different for different wavelengths. 
Photosynthesis is important because it is responsible for the release of oxygen by green plants into the atmosphere.  

Multiple choice biology protectors of biosphere structure of chloroplast plastids photosynthetic pigments

An association is found between the wavelengths of light absorbed by chlorophyll and wavelengths of length that are associated with the greatest amount of oxygen released by plants. Based on the observation, the function of chlorophyll is

  1. It plays a role in cell respiration.

  2. It plays a role in the light reactions of photosynthesis.
  3. It takes part in $H _2O$ release.
  4. It takes part in $CO _2$ fixation.

  5. It generates energy.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Chlorophyll absorbs sunlight of particular wavelength that causes spitting of water at water splitting complex of photosystem II and oxygen gas is released. PSI absorbs light below 680nm while PS II is activated by light below 700 nm; so plants exhibit maximum amount of oxygen released when illuminated with simultaneous exposure to red and far red light. Fixation of $CO _2$ occurs during the dark reaction. Thus, the correct answer is B.

Multiple choice biology protectors of biosphere structure of chloroplast plastids photosynthetic pigments

Total amount of dry weight of photosynthate produced by all type of plants per annum is

  1. 1.7 million tonnes

  2. 17 million tonnes

  3. 17000 million tonnes

  4. 170000 million tonnes
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total amount of dry weight of photosynthate produced by all type of plants per annum is 170000 million tonnes. There are several factors, which limit the formation of dry weight such as reduced nitrogen fixation which will result in reduction of dry weight.

Therefore, the correct answer is option (D).

Multiple choice biology protectors of biosphere structure of chloroplast plastids photosynthetic pigments

The site of photosynthesis in blue green algae is

  1. Chromatophores

  2. Mitochondria

  3. Chloroplast

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

Blue green algae are prokaryotic orgnanisms and lack membrane bound organelles. Mitochondria and cholroplast are double membrane bound organelles of eukaryotes that serve as site of aerobic respiration and photosynthesis respectively. Chromatophores are the pigment containing membranous structures that serve as site for photosynthesis in BGA. Correct answer is A.

Multiple choice biology protectors of biosphere structure of chloroplast plastids photosynthetic pigments

Intact chloroplasts can be isolated with the help of

  1. Alcohol

  2. Acetone

  3. Carbon disulphide

  4. Sugar solution
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Intact chloroplast from green leaves can be isolated by the acetone isolation method. The membranes of the chloroplast are proteinaceous in nature so it can be easily isolated by acetone. The samples obtained are loaded to the chromatography apparatus, which shows bands on the chromatogram.

So, the correct option is B. 

Multiple choice biology protectors of biosphere structure of chloroplast plastids photosynthetic pigments

Number of grana present in a chloroplast is

  1. 10-20

  2. 20-30

  3. 30-40

  4. 40-60
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • A thylakoid refers to the membrane-bound internal compartment within the chloroplasts of a plant cell and cyanobacteria.
  • It is a site for light-dependent reactions of photosynthesis. 
  • It is made up of a thylakoid membrane which surrounds the thylakoid lumen.
  • A stack of thylakoid disk is organized to form grana.
  • Within a chloroplast of a plant cell, there are about 40- 60 grana and each granum are composed of 10 to 100 thylakoids.
  • So, the correct answer is '40-60'.
Multiple choice biology protectors of biosphere structure of chloroplast plastids photosynthetic pigments

Particles of thylakoid membranes involved in ATP synthesis are called

  1. Quantasomes
  2. $CF _0-CF _1$

  3. Photosystems

  4. Pyrenoids
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • The particles of thylakoid membrane responsible for ATP synthesis is a CF$ _1$ -CF$ _O$-ATP synthase.
  • It is embedded in the thylakoid membrane where the CF$ _1$-part is attached to the stroma. 
  • Therefore, ATP synthesis occurs on the stromal side of the thylakoid where the ATP molecules are required for carrying out the light-independent reactions of photosynthesis.
  • So, the correct answer is 'CF$ _0$−CF$ _1$'.