Tag: photosynthesis

Questions Related to photosynthesis

State whether the following statements are true or false
The ultimate electron donor in photosynthesis is water

botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

In oxygenic photosynthesis, the first electron donor is water, creating oxygen as a waste product. In anoxygenic photosynthesis, various electron donors are used. Cytochrome b6f and ATP synthase work together to create ATP. This process is called photophosphorylation.

Thus, the correct answer is 'True.'

Which statements is correct for given reaction for photosynthesis:-
${ 2H } _{ 2 }A+C{ O } _{ 2 }\underrightarrow { light } 2A+{ C }H _{ 2 }O+{ H } _{ 2 }O$

botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

  1. H donor from ${ H } _{ 2 }O$ if reducible compound is ${ H } _{ 2 }O$

  2. ${ O } _{ 2 }$ evolve from ${ H } _{ 2 }O$ if a reducible compound is${ H } _{ 2 }O$

  3. Glucose gain its oxygen from ${ H } _{ 2 }O$

  4. $(1)$ & $(3)$ both

Show answer
Correct Option: B
Explanation:

The oxygen evolution is part of the light-dependent reactions of photosynthesis in cyanobacteria and the chloroplasts of green algae and plants. It utilizes the energy of light to split a water molecule into its protons and electrons for photosynthesis. Free oxygen, generated as a by-product of this reaction, is released into the atmosphere.

So, the correct option is 'O$ _{2}$ evolve from H$ _{2}$O if a reducible compound is H$ _{2}$O'

Refer to the given reaction.
$2H _{2}O \rightarrow 4H^{+} + O _{2} + 4{e^-}$
Where does this reaction take place in the chloroplasts of plants?

botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

  1. Outer surface of thylakoid membrane

  2. Inner surface of thylakoid membrane

  3. In the matrix (stroma)

  4. Intermembrane space

Show answer
Correct Option: B
Explanation:
The splitting of water is associated with the PS II. Water is split into $H^{+},[O]$ and electrons. The electrons needed to replace those removed from photosystem I are provided by photosystem II. 
   $2H _{2}O\rightarrow  4H^{+} + O _{2} + 4 _{e^-}$
Water splitting complex is associated with the PSII, which itself is physically located on the inner side of the membrane of the thylakoid.
So the correct answer is 'Inner surface of thylakoid membrane'.

In the light reaction the energy is absorbed by chlorophyll. The absorbed energy is used in splitting the water molecule into its two components and releasing electrons $(H _2O\longrightarrow2H^+ +O _2+2e)$, this reaction is known as :

botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

  1. Analysis of water

  2. Photolysis of water

  3. Decomposition of water

  4. All above.

Show answer
Correct Option: B
Explanation:

In the light reaction of photosynthesis, chlorophyll molecule absorbs light energy, results in the splitting of water molecules, results in the release of protons, electrons and nascent oxygen. This process is called Photolysis of water. It occur in the lumen of thylakoid.

So, the correct option is ‘photolysis of water’

The process in which water is split during photosynthesis is

botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

  1. Photolysis

  2. Hydrolysis

  3. Plasmolysis

  4. Hemolysis

Show answer
Correct Option: A
Explanation:

Photolysis of water occurs at grana i.e., lumen side of grana thylakoid membrane with the help of water splitting complex or OEC (oxygen evolvong complex). This step is associated with PS- II of Z- scheme.

Three minerals Mn ion, ${Ca}^++,{Cl}^-$ are associated with splitting of water.
So, the correct answer is 'Photolysis'.

Oxygen is released in photosynthesis by

botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

  1. photophosphorylation

  2. photolysis of water

  3. photorespiration

  4. photons

Show answer
Correct Option: B
Explanation:

This part of photosynthesis occurs in the granum of a chloroplast where light is absorbed by chlorophyll; a type of photosynthetic pigment that converts the light to chemical energy. This reacts with water (H2O) and splits the oxygen and hydrogen molecules apart. In the first stage of photosynthesis light energy is absorbed by chlorophyll in plant cells. This light energy is then used to produce ATP and to split water into hydrogen and oxygen. The splitting of water is referred to as photolysis. 

So, the correct option is, 'photolysis of water'.

An example of CAM plant is

botany photosynthesis cam cycle cam plants photosynthetic cycle

  1. Black Nightshade (Solanum nigrum)

  2. Lemon Grass (Cymbopogon flexuosus)

  3. Sugarbeet (Beta vulgaris)

  4. Snake Plant (Sanseveria trifasciata)

Show answer
Correct Option: D
Explanation:

Certain plants which have Crassulacean Acid Metabolism (CAM) are known as CAM plants. They have scotoactive stomata. It means their stomata remain open during the night. It is the characteristic feature of CAM plants. These plants fix carbon dioxide during the night but form sugars only during the day when RuBisCO is active. Sedum, Kalanchoe, Pineapple, Opuntia, Snake plant are the examples of CAM plants. These plants also perform double carbon dioxide fixation. The carbon dioxide acceptor in CAM plants is Phosphoenol pyruvic acid (PEP) during the night and Ribulose bisphosphate is carbon dioxide acceptor during the daytime. The first stable product in case of CAM plants is Oxalo acetic acid (OAA).

In CAM plants, $CO _2$ required for photosynthesis enters the plant body during

botany photosynthesis cam cycle cam plants photosynthetic cycle

  1. Daytime when the stomata are open.

  2. Night when the hydathodes are open.

  3. Daytime through the lenticels.

  4. Nights through the stomata which are kept open.

Show answer
Correct Option: D
Explanation:

CAM plants are those plants whose stomata open at night so that they can fix carbon-dioxide in the form of organic acids because these plants are adapted to grow in arid conditions. They accumulate carbon dioxide at night in vacuoles whereas in day time malic acid in transported to chloroplasts where it is again converted into carbon dioxide for photosynthesis. 

Thus, the correct answer is option D. 

Which one of the following is a CAM plant?

botany photosynthesis cam cycle cam plants photosynthetic cycle

  1. Maize

  2. Kalanchoe

  3. Sugarcane

  4. Jowar

Show answer
Correct Option: B
Explanation:
CAM stands for Crassulacean Acid Metabolism. Most of the plants open their stomata during the day to exchange gases but these plants open them during the night. It is because these grow in extremely dry areas.
CAM plants take in CO₂ at night and store it in the form of a four-carbon acid called “malate.” 
Then the malate is released during the day, where it can be combined with the ATP and NADPH created by the sunlight.
Examples-Kalanchoe, Cacti
Rest 3 plants belong to C₄ plants.
So, the correct option is 'Kalanchoe'

The carbon dioxide acceptor in CAM plants is

botany photosynthesis cam cycle cam plants photosynthetic cycle

  1. Malic acid

  2. Oxalo-acetic acid

  3. Pyruvic acid

  4. Phosphoenol pyruvic acid

Show answer
Correct Option: D
Explanation:

Certain plants which have Crassulacean Acid metabolism (CAM) are known as CAM plants. They have scotoactive stomata. These plants fix carbon dioxide during the night but form sugars only during the day when RuBisCO is active. sedum, kalanchoe, pineapple, opuntia are the examples of CAM plants. These plants also perform double carbon dioxide fixation. The carbon dioxide acceptor in CAM plants is Phosphoenol pyruvic acid (PEP) during the night and Ribulose bisphosphate is carbon dioxide acceptor during day time. The first stable product in case of CAM plants is Oxalo acetic acid (OAA).