Biology

Photosynthesis in Plants

1,492 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 metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

In light phase of photosynthesis there is formation of

  1. $ATP$
  2. $NADPH _2$
  3. Both $ATP$ and $NADPH _2$

  4. Carbohydrates.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In light-dependent reactions, the energy from sunlight is absorbed by chlorophyll and converted into chemical energy in the form of electron carrier molecules like ATP and NADPH.

Light energy is harnessed in Photosystems I and II, both of which are present in the thylakoid membranes of chloroplasts.
Just as the name implies, light-dependent reactions require sunlight. In the light-dependent reactions, energy from sunlight is absorbed by chlorophyll and converted into stored chemical energy, in the form of the electron carrier molecule NADPH (nicotinamide adenine dinucleotide phosphate) and the energy currency molecule ATP (adenosine triphosphate). The light-dependent reactions take place in the thylakoid membranes in the granum (stack of thylakoids), within the chloroplast.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

Light phase consists of

  1. Two photochemical reactions

  2. Two photosynthetic units

  3. Two chloroplast parts

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

Light phase is also known as a photochemical phase because it is a light dependent phase. During this phase, the formation of high-energy chemical intermediates ATP and NADPH$ _{2}$ takes place. ATP and NADPH$ _{2}$ are the assimilatory power of photosynthesis. Light phase also includes light absorption, water splitting and release of oxygen. Two photosynthetic units called Photosystem I and Photosystem II are also involved in light phase. Light phase consists of two photochemical reactions, i.e. non-cyclic photophosphorylation and cyclic photophosphorylation.

Non-cyclic phosphorylation involves both Photosystem I and Photosystem II. These two photosystems work in series, first PS II and then PS I. NADPH is synthesized by this kind of electron flow. 
Cyclic photophosphorylation is performed by photosystem I independently. It produces ATP only. It does not involve the formation of NADPH. 

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

Light reaction of photosynthesis occur in 

  1. Only absence of light

  2. Only presence of light

  3. Presence and absence of light

  4. Absence of light in maximum intensity
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In photosynthesis, the light-dependent reactions take place on the thylakoid membranes. The light-independent reactions take place in the stroma. The thylakoid membrane contains some integral membrane protein complexes that catalyze the light reactions. There are four major protein complexes in the thylakoid membrane Photosystem II (PSII), Cytochrome b6f complex, Photosystem I (PSI), and ATP synthase. These four complexes work together to ultimately create the products ATP and NADPH.

So, the correct answer is option B.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

The products of photochemical reaction are

  1. $O _2$, ATP and NADPH
  2. $O _2$

  3. ATP and NADPH

  4. Organic compounds especially carbohydrates.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Light reactions of photosynthesis which takes place in thylakoids membranes of chloroplast utilize sunlight and water to produce oxygen, ATP and NADPH.

The energy from the sun is converted to ATP and NADPH which is later utilised in the dark reaction to produce organic compound glucose, hence organic compound is a byproduct of the dark reaction.  
Therefore option A is the ans 

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

In photosynthesis light energy is utilized in 

  1. Converting ATP into ADP
  2. Changing CO$ _{2}$ into carbohydrate

  3. Converting ADP into ATP

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

Photosynthesis is a process in which phosphorylation occurs. Phosphorylation is a process in which phosphate group is added, and in the case of photosynthesis it happens in the presence of light, thus called as 'photophosphorylation'. ADP is converted to ATP, the energy currency as the main product of this process. In photosynthesis, cyclic and non-cyclic photophosphorylation takes place in the light phase and generate ATP and NADPH.

So, the correct answer is option C.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

Raw materials required for light reactions are

  1. ADP and $H _2O$
  2. ADP, $H _2O$ and NADP
  3. ADP and $NADPH _2$

  4. ATP and NADP.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A) ADP and ${ H } _{ 2 }O$ are required in addition to NADP.

B) ADP, ${ H } _{ 2 }O$ and NADP are the raw materials used to produce ATP and NADPH.
C) NADPH is a product of the light reaction.
D) ATP is a product of the light reaction.
So the correct answer is 'ADP, ${ H } _{ 2 }O$ and NADP'.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

Excitation of chlorophyll by light is

  1. Exergonic reaction

  2. Anabolic reaction

  3. Photochemical reaction

  4. Photooxidation reaction
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The first and foremost step of photosynthesis is the excitation of chlorophyll molecule which occurs with the absorption of light. This reaction is photochemical reaction since involves light and results in chemical change by transfer of electrons. The pigments present in the photosystems absorb photon of light. The photons excite electrons in the chlorophyll which then move through the electron transport chain and results in the production of carbohydrates and energy packets NADPH, ATP with the release of oxygen.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

Light reaction of photosynthesis is also called

  1. Calvin cycle

  2. Hill reaction

  3. TCA cycle

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

The Hill reaction implies that the light-dependent reaction of photosynthesis is a result of a series of redox reactions and a suitable terminal electron acceptor is required for that reaction to occur. Hence, solar energy is converted to chemical energy by the reduction of NADP to NADPH.


So, the correct option is 'Hill reaction'.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

First reaction in photosynthesis is

  1. Photolysis of water

  2. Excitation of chlorophyll molecules

  3. Formation of ATP
  4. Fixation of CO$ _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

During the first stage of photosynthesis, called the light-dependent reaction, sunlight excites the electrons in the chlorophyll pigment. The organism uses this energy to create the energy carrier molecules ATP and NADPH, which are crucial for carbon fixing during the second stage.


So, the correct option is 'Excitation of chlorophyll molecules'.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

In plants, food formation during photosynthesis takes place

  1. In root

  2. In leaf

  3. In stem

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

Photosynthesis is the process by which plant utilizes the energy obtained from sunlight to produce glucose from carbon dioxide and water. During this process, oxygen is released as the by product. It takes place in leaf cells. Leaf cells contain chloroplasts. The chloroplasts contain green pigment chlorophyll which prepares the food during photosynthesis.

Thus, the correct answer is 'In leaf'.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

Red drop and Emerson effect have proved the existence of ______________.

  1. Light and dark reactions is photosynthesis

  2. Two distinct photo systems is photosynthesis

  3. The supply of electrons from oxygen evolving complex
  4. Electron transport from water to NDAP$+$ across thylakoids
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

When sun light hits the chloroplast, then

  1. Increase in $pH$ of thylakoid lumen relative to stroma occurs
  2. A measurable decreases in $pH$ in the thylakoid lumen relative to stroma occurs
  3. A measurable decrease in $pH$ in the stroma relative to thylakoid lumen occurs
  4. The $pH$ of both stroma and thylakoid luman becomes equal
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When the light hits the chloroplast, the chemiosmotic potential is established by thylakoid membrane. The carriers in the electron transport chain use some of the electron’s energy to actively transport protons from the stroma to the lumen. During photosynthesis, the lumen becomes acidic, as low as pH 4, compared to pH 8 in the stroma. Therefore answer B is correct.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

In plants, light-dependent reactions proceed at the

  1. cytoplasm

  2. stroma

  3. plasma membrane

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

In plants, the light reactions take place in the thylakoid membranes of organelles called chloroplasts. The light-dependent reactions use light energy to make two molecules needed for the next stage of photosynthesis: the energy storage molecule ATP and the reduced electron carrier NADPH. 

So, the correct option is, 'thylakoid membrane'.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

Choose the correct answer from the alternatives given.
The first step in photosynthesis is

  1. formation bf $NADPH _2$

  2. photolysis of water

  3. formation of ATP

  4. excitation of an electron of chlorophyll by a photon of light
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

During the first stage of photosynthesis, called the light-dependent reaction, sunlight excites the electrons in the chlorophyll pigment. The organism uses this energy to create the energy carrier molecules ATP and NADPH, which are crucial for carbon fixing during the second stage. 

Thus, the correct answer is 'Excitation of an electron of chlorophyll by a photon of light.'

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

Photophosphorylation in chloroplast requires movement of:

  1. electrons across the membrane

  2. ions across the membrane

  3. protons across the membrane

  4. electrons and protons across the membrane
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Phosphorylation in the electron-transport chain in the mitochondrion.

Hence the correct answer is A.