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 photosynthesis cam cycle cam plants photosynthetic cycle

In overall photosynthetic pathway, for one molecule of $O _2$ liberated eight light quanta are required two molecules of NADPH$2$ are formed. Beside this, certain amount of energy is also released along with electron transport. This energy is liberated as.

  1. $2$ ATP molecules
  2. $8$ ATP molecules
  3. $3$ ATP molecules
  4. $4$ ATP molecules
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the light-dependent reactions of photosynthesis, the electron transport chain generates a proton gradient that drives the synthesis of ATP. For the production of 2 NADPH, 2 ATP are typically produced via non-cyclic photophosphorylation.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

$CO _{2} : NADPH _{2} : ATP$ ratio for $C _{4}$ plants is

  1. $1 : 2 : 3$
  2. $2 : 3 : 4$
  3. $1 : 2 : 5$
  4. $1 : 5 : 10$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In C$ _4$ pathway for production of one molecule of glucose we require 12 NADPH$ _2$, 30 ATP and 6CO$ _2$ are required.

CO$ _2$ : NADPH$ _2$ : ATP =  6 : 12 : 30

CO$ _2$ : NADPH$ _2$ : ATP =  1 : 2 : 5

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

Internal source of CO2 in CAM plants is

  1. Oxaloacetic acid

  2. Malic acid

  3. RUBP

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

In  CAM plant, the stomata in the leaves remain shut during the day to reduce evapotranspiration, but open at night to collect CO$ _{2}$. This CO$ _{2}$ is fixed into oxaloacetate by PEP carboxylase, which is then converted to malate. The CO$ _{2}$ is stored as malate in vacuoles at night, and then in the daytime, it is transported to chloroplasts where it is converted back to CO$ _{2}$, which is then used during photosynthesis.  

So, the correct option is 'Oxalo acetic acid'.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In CAM plants, $ C{ O } _{ 2 } $ acceptor is

  1. RuBP

  2. PEP

  3. OAA

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

Crassulacean Acid Metabolism (CAM) is a specialised photosynthetic process which is characterized by the following criteria given by  Osmond (1978) and Cluge and Tuge (1978). These are:

  1. CO$ _2$ uptake takes place mainly at night
  2. stomata are open during the night and closed during the day when CO$ _2$ uptake is mostly negligible.
  3. Malate accumulates at night by carboxylation of PEP.
  4. Decarboxylation of malate during the day yields CO$ _2$ which is fixed up by RuBP carboxylase. 
During the night time when the stomata are open, the CO$ _2$ is absorbed and fixed by phosphoenol pyruvic acid (PEP, 3C) in presence of enzyme PEP carboxylase. As a result of this PEP gets converted into oxaloacetic acid (OAA, 4C).
So the correct option is 'PEP'

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In CAM plants, the acceptor of ${CO _2}$ is

  1. Pyruvic acid.

  2. Oxaloacetate.

  3. Phosphoenol pyruvate.

  4. Nucleic acid.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions.
  •  At low temperatures (frequently at night), plants using CAM open their stomata, CO2 molecules diffuse into the spongy mesophyll's intracellular spaces and then into the cytoplasm. Here, they can meet phosphoenolpyruvate (PEP), the CO2 acceptor.
  • Hence, In CAM plants, the acceptor of CO2 is Phosphoenolpyruvate. 
  •  So, the correct answer is 'Phosphoenol pyruvate'.
Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

The internal source of $C{ O } _{ 2 }$ in CAM plants is

  1. Oxalo-acetic acid

  2. Malic acid

  3. RUBP

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

Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions. In a plant using full CAM, the stomata in the leaves remain shut during the day to reduce evapotranspiration, but open at night to collect carbon dioxide (CO$ _2$). So the correct option is 'Oxalo-acetic acid'.
Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In which of the following respects the photosynthetic adaptations of $C _4$ plants and CAM plants are similar?

  1. In both cases, stomata normally close during the day

  2. Both types of plants make their sugar without the Calvin cycle

  3. In both cases, an enzyme other than rubisco carries out the first step in carbon fixation
  4. Neither $C _4$ plants nor CAM plants have grana in their chloroplasts
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$C _4$ and CAM  plants are plants that use certain special compounds to gather carbon dioxide (CO 2 ) during photosynthesis. Exploitation of dry and arid habitats required adaptations in the form of $C _4$ and CAM photosynthesis, which independently evolved many times during periods of low atmospheric $CO _2$ levels carried out by carried out by a non-rubisco enzyme, PEP carboxylase, that has no tendency to bind $O _2$.

So, the correct option is, 'In both cases, an enzyme other than rubisco carries out the first step in carbon fixation'.

Multiple choice dyes dyes and pigments chemistry in daily life applied chemistry chemistry

An auxochrome is a group of atoms which will impart a particular color when
attached to a_________.

  1. chromophore

  2. chlorophyll

  3. autochrome

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

Auxochrome is a Greek word arising from; Auxo meaning to increase and chrome meaning color. An auxochrome is a group of atoms which will impart a particular color when attached to a chromophore but when present alone, will fail to produce that color.
Chromophore is that part of the molecule which when exposed to visible
light will absorb and reflect a certain color.
Hence option A is correct.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis
Read the given statements and select the correct option.
Statement 1: During photophosphorylation (of photosynthesis), light energy is utilised for the production of a proton gradient during ATP synthesis.
Statement 2: In respiration, the energy of oxidation-reduction is utilised for the phosphorylation and thus the process is called oxidative phosphorylation.

  1. Both statements 1 and 2 are correct.

  2. Statement 1 is correct but statement 2 is incorrect.

  3. Statement 1 is incorrect but statement 2 is correct.

  4. Both statements 1 and 2 are incorrect.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Photophosphorylation occurs in the grana and requires the direct sunlight energy to make energy-carrier molecules that are used in the dark reaction. The light energy is trapped by chlorophyll to make ATP and NADPH. Oxidative phosphorylation is the synthesis of energy-rich ATP molecules with the help of energy liberated during oxidation of reduced co-enzymes (NADH,${FADH} _{2}$) produced in respiration.

So the correct answer is 'Both statements 1 and 2 are correct'.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

During cyclic photophosphorylation proton gradient established by

  1. $PQ$ mediated $H^+$ transfer
  2. Photolysis of $H _2O$
  3. $NADP$ reductase mediated withdrawal of $H^+$

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

The proton gradient produced by proton pumping during the electron transport chain is used to synthesize ATP. Protons flow down their concentration gradient into the matrix through the membrane protein ATP synthase, causing it to spin & catalyze the conversion of ADP to ATP.

So, the correct option is 'PQ mediated H+ transfer'.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Differences between photophosphorylation (PP) and oxidative phosphorylation (OP) is 

  1. In PP, synthesis is of ATP while in OP it is of ADP.

  2. In PP, oxygen is evolved while in OP oxygen is taken up.

  3. Both cannot take place in light.

  4. PP can take place in green leaves while OP cannot occur in green leaves.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Both the oxidative phosphorylation and photophosphorylation are in which cells make energy in the form of ATP, oxidative phosphorylation occurs during cell respiration and photophosphorylation occurs during photosynthesis. Oxygen is released during photophosphorylation and oxygen is taken up.

So the correct option s 'In PP, oxygen is evolved while in OP oxygen is taken up'.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

In mechanism, photophosphorylation is very similar to

  1. substrate-level phosphorylation

  2. oxidative phosphorylation

  3. Calvin cycle

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

Oxidative phosphorylation is the process in which ATP is formed by the transfer of electrons from NADH or FADH 2 to O 2 by a series of electron carriers. The sunlight-driven production of ATP from ADP and inorganic phosphate is called photophosphorylation.

So, the correct option is, 'oxidative phosphorylation'.

Multiple choice chemistry nitrogen and sulfur sulfur and its oxides acid deposition natural resources- air, water and land

The loss or reduction of chlorophyll in the leaves is termed as:

  1. necrosis

  2. chlorosis

  3. epinasty

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

Necrosis is the death of body tissue. It occurs when there is some infection or the supply to the part of the plant has stopped. This can also occur from injury, radiation or chemicals.
Chlorosis is yellowing of leaf tissue due to lack of chlorophyll. Possible causes of chlorosis include poor drainage, damaged roots, and compacted roots.
Epinasty is increased growth on the upper surface of an organ or part, causing it to bend downward.
Lichens are made up of two or more closely interacting organisms, a fungus and one or more partners called photobionts. 
Thus, the correct answer is option B. 

Multiple choice bio-chemistry absorption by roots - the processes involved diffusion transport across membrane means of transport

In photosynthesis, oxygen is given out by the process of

  1. Diffusion

  2. Osmosis

  3. Transpiration

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

Diffusion is a process in which the molecules intermingle due to their kinetic energy and movement of molecules is from higher concentration to lower concentration. During photosynthesis, the plant produces oxygen as a byproduct and hence the concentration of oxygen inside the cell is higher than the outer environment. Plant releases oxygen in external environment through diffusion process.