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 plant diseases keeping diseases away biology

On the basis of symptoms of chlorosis in leaves a student inferred that this was due to deficiency of nitrogen. This inference could be correct only if we assume that yellowing of leaves appeared first in.

  1. Old leaves

  2. Young leaves

  3. Young leaves followed by mature leaves

  4. Mature leaves followed by young leaves
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

  • On the basis of the symptoms of chlorosis in the leaves, a student inferred that this was due to the deficiency of nitrogen. 
  • This may be correct inference only if yellowing of leaves appeared first in young leaves then in old leaves. But Chlorosis is the main symptom of nitrogen deficiency. 
  • Therefore, the leaves gradually become pale or yellow. These will first appear in old leaves and then in young leaves.
  • The correct option is A.

Multiple choice development of plants plant growth growth and development plant growth and development biology

Most effective wavelength of light for photosynthesis is

  1. Green

  2. Violet

  3. Red

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

Light is an essential factor for photosynthesis. There is a linear relationship between incident light and $CO _{2}$ fixation at low light intensities. At higher light intensities, gradually the rate does not show further increase as other factors become limiting. Light between 400-700 nm wavelength constitute the photosynthetically active radiation (PAR). Maximum photosynthesis takes place in red and blue light of the visible spectrum and minimum photosynthesis takes place in the green light. The most effective wavelength of light for photosynthesis is red because maximum absorption by chlorophyll a takes place in the red light.

Multiple choice development of plants plant growth growth and development plant growth and development biology

Maximum absorption of light by chlorophyll a occurs in which regions of the absorption spectrum (a) Blue (b) Red (c) Green (d) Yellow

  1. a and b only

  2. b and c only

  3. a and d only

  4. b and d only
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Answer is option A i.e. "a and b only"
Light between 400-700 nm wavelength constitute the photosynthetically active radiation (PAR). Maximum absorption of light by chlorophyll a occurs in red and blue regions of the absorption spectrum. So that, the rate of photosynthesis is maximum in red and blue light of the visible spectrum.

Multiple choice development of plants plant growth growth and development plant growth and development biology

The pigment involved in red-far red light interconversion is ......................

  1. Cytochrome

  2. Xanthophyll

  3. Lycopene

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

Phytochrome is responsible for absorption of red and far red light it is involved in red-far red light interconversion. Phytochrome is a photoreceptor, a pigment that plants use to detect light. It is sensitive to light in the red and far red region of the visible spectrum.

Multiple choice development of plants plant growth growth and development plant growth and development biology

Which one shows red $\rightleftharpoons$ far-red interconversions?

  1. Carotenoids

  2. Cytochromes

  3. Chlorophylls

  4. Phytochrome
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Phytochromes are photoreceptor found in plants that detects light. The different phytochromes are involved in different biological responses to red light. P$ _r$ is inactive form whereas P$ _{fr}$ is an active form of phytochrome. When exposed to red light, P$ _r$ is converted to P$ _{fr}$. This active form then initiates many biological processes in plants.
Thus, the correct answer is option D.
Multiple choice development of plants plant growth growth and development plant growth and development biology

The pigment which mainly absorbs red and far-red radiation in plants, is known as

  1. Cytochrome

  2. Xanthophyll

  3. Phytochrome

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

Phytochrome is blue colored pigment present in the plants. It is a photoreceptor chromoprotein. It is mainly found in flowering plants. These are responsible for flowering. It mainly absorbs red and far-red radiation in plants and induces flowering process.

Thus, the correct answer is option C.

Multiple choice development of plants plant growth growth and development plant growth and development biology

Phytochrome is associated with

  1. ${P} _{r}$ and ${P} _{fr}$ reactions
  2. Absorption of red light of $660 nm$
  3. Absorption of far-red light of $740 nm$

  4. Absorption of blue-light by leaves
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Phytochromes are photoreceptor found in plants that detects light. The different phytochromes are involved in different biological responses to red light. P$ _r$ is inactive form whereas P$ _{fr}$ is active form of phytochrome. When exposed to red light,  P$ _r$ is converted to P$ _{fr}$. This active form then initiate many biological processes in plants.

Thus, the correct answer is 'Option A'.

Multiple choice geography what is around us? atmosphere and its structures the atmosphere components of earth elements of weather and climate : temperature the earth's structure

Through the process of photosynthesis plants absorb ___ from the atmosphere and release ___ into it.

  1. Carbon dioxide, oxygen

  2. Exhaustible

  3. Non-renewable

  4. Natural
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Carbon dioxide, oxygen.
Photosynthesis is the process by which plants, some bacteria, and some protistans use the energy from sunlight to produce glucose from carbon dioxide and water. This glucose can be converted into pyruvate which releases adenosine triphosphate (ATP) by cellular respiration. Oxygen is also formed.

Photosynthesis may be summarised by the word equation:

carbon dioxide + water arrow with sunlight and chlorophyll glucose + oxygen
The conversion of usable sunlight energy into chemical energy is associated with the action of the green pigment chlorophyll.
Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

During photosynthesis 

  1. $O _{2}$ evolved comes from $CO _{2}$

  2. ATP is formed

  3. ATP is not formed

  4. Water is required as medium but it does not take part in photosynthesis
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Photosynthesis is an anabolic process, which helps in forming ATP, where it is called as energy currency. During the light reaction photophosphorylation takes place producing ATP and $NADPH _2$ which is used as energy source for dark reaction.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

Light reaction in stroma lamellae of chloroplast results in the production of

  1. ATP
  2. NADPH$ _2$
  3. ATP + NADPH$ _2$
  4. O$ _2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A) Along with ATP, ${ NADPH } _{ 2 }$ is also produced.
B) Along with ${ NADPH } _{ 2 }$, ATP is also produced.

C) The light reaction that takes place in the stroma lamellae is the non-cyclic phosphorylation and ATP and ${ NADPH } _{ 2 }$ are the products.
D) Oxygen is also liberated during the light reaction but is not the main product.
So the correct answer is 'ATP + ${ NADPH } _{ 2 }$'.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

With reference to photosynthesis, what is the $CF _0$ - $CF _1$ complex?

  1. ATP synthetase

  2. Ferredoxin-NADP reductase
  3. Cytochrome $b6$/f complex

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

The CF0-CF1 complex is the ATP synthase enzyme found in the thylakoid membrane of chloroplasts, responsible for synthesizing ATP during the light reactions.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

Which of the following step of photosynthesis is not directey involve in ATP synthesis or consumption?

  1. Corboxylation of dark Rection

  2. Reduction of dark reaction

  3. Cyclic photo phosphorylation of light reaction

  4. Regeneration of dark reaction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Carboxylation of the dark reaction (Calvin cycle) does not directly involve ATP synthesis or consumption. The enzyme RuBisCO catalyzes CO2 fixation with RuBP without ATP. Both reduction and regeneration phases consume ATP, and cyclic photophosphorylation produces ATP.