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 botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

Extrusion of electron from reaction centre of PS II leaves a hole which is filled by electron released from

  1. $H _2O$
  2. $CO _2$

  3. Chlorophyll

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

Non-cyclic phosphorylation involves both Photosystem I and Photosystem II. These two photosystems work in series, first PS II and then PS I. The two photosystems are connected through an electron transport chain. $NADPH$ is synthesized by this kind of electron flow. Electrons are transferred from the PS II and then passed on to the pigments of PS I. Then, electrons get excited and transferred to another acceptor. These electrons are then moved downhill again to a molecule of $NADP^{+}$. The addition of these electrons results in the formation of $NADPH$. Extrusion of the electron from reaction centre of PS II leaves a hole which is filled by electron released from $H _{2}O$. This is achieved by electrons available due to the splitting of water. The water splitting complex is associated with PS II, which itself is physically located on the inner side of the membrane of the thylakoid. Water is split into $H^{+}$, $O$ and electrons. The protons and oxygen formed by splitting of water is released within the lumen of the thylakoids. The oxygen produced is released as one of the net products of photosynthesis.

$2H _{2}O$ $\longrightarrow$ $4H^{+}$ + $O _{2}$ + $4e^{-}$

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

Isotope of oxygen used in studying photolysis is

  1. $^{16}O$
  2. $^{15}O$
  3. $^{17}O$
  4. $^{18}O$
Reveal answer Fill a bubble to check yourself
D Correct answer
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 }$'.

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

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

  1. Absorption of light
  2. $CO _2$ assimilation

  3. Photolysis of water

  4. ATP synthesis
Reveal answer Fill a bubble to check yourself
C Correct answer
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'

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

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

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
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.'

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

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

  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
Reveal answer Fill a bubble to check yourself
B Correct answer
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'

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

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?

  1. Outer surface of thylakoid membrane

  2. Inner surface of thylakoid membrane

  3. In the matrix (stroma)

  4. Intermembrane space
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.
Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

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 :

  1. Analysis of water

  2. Photolysis of water

  3. Decomposition of water

  4. All above.
Reveal answer Fill a bubble to check yourself
B Correct answer
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’

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

The process in which water is split during photosynthesis is

  1. Photolysis

  2. Hydrolysis

  3. Plasmolysis

  4. Hemolysis
Reveal answer Fill a bubble to check yourself
A Correct answer
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'.

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

Oxygen is released in photosynthesis by

  1. photophosphorylation

  2. photolysis of water

  3. photorespiration

  4. photons
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.

Multiple choice botany ecological adaptations, succession and ecological services extreme adaptations adapting to a habit adaptive features aquatic plant adaptations pollination through water

In xerophytes, photosynthesis often occurs through

  1. Root

  2. Modified stem

  3. Stomata

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

In many xerophytes, leaves are reduced to spines to prevent water loss. Consequently, the stem becomes green and photosynthetic (cladode or phylloclade) to perform the function of leaves.

Multiple choice biology adapting to a habit extreme adaptations adaptive features adaptations of organisms

Shade plants have low

  1. Photosynthetic activity

  2. Respiratory rate

  3. Metabolic activity

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

Shade plants (sciophytes) are adapted to low-light environments, which results in lower overall metabolic rates, including reduced photosynthetic and respiratory activity compared to sun-loving plants. Because they operate at lower energy levels, all these metabolic processes are typically lower.

Multiple choice photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

The photocenter P${ _7}$${ _0}$${ _0}$ is present in

  1. Photosystem I

  2. Photosystem II

  3. Both A and B

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

Photosystems are functional and structural units of protein complexes involved in photosynthesis, that together carry out the primary photochemistry of photosynthesis: the absorption of light and the transfer of energy and electrons. There are 2 kinds of photosystems - photosystem I and II. In photosystem I, the reaction center is P-${ _7}$${ _0}$${ _0}$. In photosystem II, the reaction centers are P-${ _6}$${ _8}$${ _3}$. Thus, the correct answer is option A. 

Multiple choice photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

$P _{680}$ is related with  

  1. PS- I

  2. PS- II

  3. Hill reaction

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

P$ _{680}$ is the primary donor present in photosystem II. Structurally,  it's chlorophyll pigment dimer is present at the center of photosystem II. 680 suggests that the absorption is maximum at 680nm in red light. P$ _{680}$ or primary donor receives energy either by absorbing light or by excitation of electrons present in nearby chlorophyll. The excited electrons get captured by electron acceptor present in photosystem II, which is pheophytin and oxidized P$ _{680}$ is then reduced by electron generated from water during oxygenic photosynthesis.

Multiple choice photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

Ferredoxin is a constituent of

  1. PS I

  2. PS II

  3. Hill reaction
  4. $P _{680}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ferredoxin is the iron-containing, soluble compound in chloroplasts that helps in electron transportation and is the constituent of PS I which asses electrons to reductase complex that helps in the reduction of NADP$^+$ to NADPH which is a strong reducing agent.

So the correct option is 'PS I'.