Tag: photosystems

Questions Related to photosystems

Isotope of oxygen used in studying photolysis is

botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

  1. $^{16}O$

  2. $^{15}O$

  3. $^{17}O$

  4. $^{18}O$

Show answer
Correct Option: D
Explanation:

A) $ _{ \quad  }^{ 16 }{ O }$ is not used to study photolysis.
B) $ _{ \quad  }^{ 15 }{ O }$ is not used to study photolysis.

C) $ _{ \quad  }^{ 17 }{ O }$ is not used to study photolysis.
D) $ _{ \quad  }^{ 18 }{ O }$ is the isotope that is abundantly present and is used in the study of photolysis.
So the correct answer is '$ _{ \quad  }^{ 18 }{ O }$'.

Mineral involved in photolysis of water are
(a) Mn
(b) Ca
(c) Mg
(d) Cl

botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

  1. a, b

  2. a, b, d

  3. c, d

  4. a, b, c

Show answer
Correct Option: B
Explanation:

A) Mn and Ca are involved in the photolysis of water.
B) Mn, Cl and Ca are involved in the photolysis of water.

C) Mg is not involved in the photolysis of water while Cl is involved.
D) Mn and Ca are involved in the photolysis of water. but Mg is not involved.
So the correct answer is 'a, b, d'.

Mn, Ca and Cl present in PS II play an important role in

botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

  1. Absorption of light

  2. $CO _2$ assimilation

  3. Photolysis of water

  4. ATP synthesis

Show answer
Correct Option: C
Explanation:

A) Absorption of light is carried out by photosynthetic pigments.

B) Carbon dioxide assimilation is done by enzymes in the mesophyll cells.
C)| Mn, Ca and Cl are present in the light-harvesting complex (LHC) of PS II and help in the splitting of water
D) PS I and PS II are involved in ATP synthesis
So, the correct answer is 'Photolysis of water'

The essential element required for water splitting in photosynthesis leading  to release of oxygen is

botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

  1. Mo

  2. Mn

  3. Mg

  4. K

Show answer
Correct Option: B
Explanation:

During ATP synthesis in the chloroplast, the proton gradient is formed. There are several processes that take place during activation of electrons and their transport which lead to the development of a proton gradient. Photolysis of water is the first process of this activation. The splitting of the water molecule takes place on the inner side of the thylakoid membrane and so the hydrogen ions (protons) that are produced, they accumulate within the lumen of the thylakoids. Oxygen-evolving complex called Z-enzyme is attached to the inner surface of the thylakoid membrane. The enzyme has four Mn ions. Light energized  Mn and removes electrons from $OH^{-}$ component of water forming oxygen. So, the essential element required for water splitting in photosynthesis leading to release of oxygen is Mn.

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'.