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 c3, c4 and cam plants photosynthesis in higher plants biology

Which of the following photosynthetic characteristics are present in $C _3$ plants but not in $C _4$ plants?
a. $CO _2$ compensation point of $45$ ppm
b. Relatively higher rate of photo respiratory $CO _2$ evolution
c. Presence of well developed bundle sheath
d. Initial involvement of RuBP carboxyl's(RuBis CO) in $CO _2$ assimilation.
Select the correct answer using the codes given.

  1. $1, 2$ and $3$
  2. $1, 2$ and $4$
  3. $1, 3$ and $4$
  4. $2$ and $4$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

C3 plants possess a higher CO2 compensation point, a higher rate of photorespiration, and initially use RuBisCO for carbon fixation via the Calvin cycle. Bundle sheath cells are characteristic of C4 plants, not C3 plants, which lack Kranz anatomy.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

$C _4$ plants are more efficient in photosynthesis than $C _3$ plants because of.

  1. Higher leaf area

  2. The presence of a large number of chloroplasts

  3. The presence of a thin cuticle on the leaf surface

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

C4 plants are more efficient than C3 plants primarily because they virtually eliminate photorespiration. They concentrate CO2 around RuBisCO in bundle sheath cells, preventing the oxygenase activity that wastes fixed carbon.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

$C 3$ and $C _4$ and CAM plant species are found in _________.

  1. Crassulaceae

  2. Cactaceae

  3. Euphorbiaceae

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

The family Crassulaceae is famous for containing species that exhibit CAM photosynthesis, but C3 and C4 species are also found within this diverse family.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

The fixation of $CO 2$ to malate and its decarboxylation are conunon to both $C _4$ and  $CAM$ plants, but in $CAM$ plants these events _____________.

  1. Are separated spatially

  2. Are separated temporally

  3. Require high light intensity
  4. Require high $CO _2$ concentration
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Both C4 and CAM plants fix CO2 into organic acids like malate via PEP carboxylase. However, while C4 plants separate these steps spatially between mesophyll and bundle sheath cells, CAM plants separate them temporally between day and night.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

Choose the correct answers from the alternatives given.
Cyanobacteria, unlike other types of bacteria that photosynthesize, do:

  1. not have a cell wall

  2. not have chlorophyll

  3. give off oxygen

  4. not give off oxygen
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Cyanobacteria, also called blue-green algae, were among the earliest organisms on Earth. These primitive bacteria produce oxygen during photosynthesis as they fix CO$ _2$ dissolved in the water. So the correct option is 'Give off oxygen’.
Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

If 24G-3-P molecules are formed in ${ C } _{ 3 }$ plants.Calculate a) the number of $CO _{ 2 }$ used and b) the number of G3P used for regeneration RuBP molecules

  1. $a=12, b=20$
  2. $a24, b=48$
  3. $a=12, b=24$
  4. $a=20, b=12$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In carbon fixation 5 molecules of C)@ are combines or fixed with 6 molecules; Ribulose Bisphosphate(RuBP) to make 12 molecules of PGA.

The remaining 20 G3P molecules regenerate RuBP, which enables the system to prepare for the carbon fixation step.
So, the correct option is 'a = 12, b = 20'.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

How many quanta are required to reduce one molecule of $CO _2$ and produce one molecule of $O _2$ in green plant photosynthesis?

  1. 1

  2. 8

  3. 16

  4. 32
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to photosynthetic quantum yield requirements, the reduction of one molecule of CO2 and the evolution of one molecule of O2 typically requires 8 light quanta (photons) distributed across both photosystems in standard conditions.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

In $C _4$ plants, agranal chloroplasts are found in?

  1. Mesophyll cells

  2. Epidermal cell chloroplasts of green stem

  3. Bundle sheath cells

  4. Chloroplasts of guard cells
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

C4 plants exhibit Kranz anatomy where bundle sheath cells contain large, agranal chloroplasts (lacking grana) to facilitate the Calvin cycle without oxygen interference.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

The $C _4$ plants are photosynthetically more efficient than $C _3$ plants because.

  1. The $CO _2$ compensation point is low
  2. $CO _2$ generated during photorespiration is trapped and recycled through PEP carboxylase
  3. The $CO _2$ efflux is not prevented

  4. They have more chloroplasts
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In C$ _3$ plants, three molecules of ribulose monophosphate (RuMP), 5C compound, are phosphorylated by ATP to form three molecules of ribulose bisphosphate (RuBP). RuBP is the first CO$ _2$ acceptor. It absorbs CO$ _2$ in presence of enzyme RuBP-carboxylase to form transitory or additive 6C compound, which is unstable. Three molecules of additive 6C compound immediately split up by hydrolysis into six molecules of 3C compound called 3-phosphoglyceric acid (3-PGA). C$ _3$ plants can do photosynthesis only at high concentrations of CO$ _2$. In  C$ _4$ plants, the CO$ _2$ is not directly absorbed by RuBP in presence of enzyme RuBP carboxylase as this enzyme helps to absorb CO$ _2$ having concentration of 50 ppm or more. However, C$ _4$ plants, due to high temperature and high light intensity, keep their stomata partially closed due to which the CO$ _2$ concentration goes down to 2 ppm. Hence the C$ _4$ plants can conduct photosynthesis at low concentrations of CO$ _2$.

So the correct option is 'the CO$ _2$ compensation point is low'.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

State whether the following statements are true or false.
Oxygen liberation is absent in bacterial photosynthesis.

  1. True

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

Oxygen liberation is absent in bacterial photosynthesis as they have pigment bacteriochlorophyll for photosynthesis and this pigment does not work in the presence of oxygen. Cyanobacteria are the only bacteria which performs oxygenic photosynthesis. 

So, the correct option is 'True'.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

Choose the correct answer from the alternatives given.
Carbon becomes available to crop plants in the form of:

  1. elemental carbon

  2. carbonates

  3. carbon dioxide

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

Plants use carbon dioxide during photosynthesis, the process whereby the plant converts the energy from the sun into a chemical carbohydrate molecule.

So the correct answer is "carbon dioxide".

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

Photosynthesis in C$ _4$ plants is relatively less limited by atmospheric C$O _2$ levels because 

  1. effective pumping of CO2 into bundle sheath calls

  2. RuBisCo in C4 plants has higher affinity for CO2

  3. four carbon acids are the initial CO2 fixation products

  4. the primary fixation of CO2 is mediated via PEP carboxylase.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Plants such as sugarcane and sorghum fix atmospheric carbon dioxide into phosphoenol pyruvic acid to produce oxaloacetic acid( a C$ _4$ acid) in the presence of phosphoenol pyruvate carbooxylase(PEP carboxylase). Such plants are called C$ _4$ plants.

In C$ _4$ plants, the primary product of OAA is mediated by PEP carboxylase, so it is relatively less limited by atmospheric CO$ _2$ levels.

So, the correct answer is 'The primary fixation of CO$ _2$ is mediated via PEP carboxylase'.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

...............fixes carbon in green plants as simple sugars

  1. Denitrification

  2. Photosynthesis

  3. Carbonation

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

Photosynthesis is a process that converts $CO _2$ into organic compounds and starch (carbohydrate) using energy from sunlight. $O _2$ is also released during this process.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

The saturation point of $CO _2$ in $C _4$ plants is?

  1. $390$ $\mu l/L$
  2. $450$ $\mu l/L$
  3. $460$ $\mu l/L$
  4. $360$ $\mu l/L$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

C4 plants are highly efficient at capturing CO2 and reach their photosynthetic saturation point at lower concentrations compared to C3 plants, typically around 360 microliters per liter.

Multiple choice hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry


Which of the following is not a pathway that relates to generation of ATP?

  1. Pentose phosphate shunt

  2. Embden-Meyerhof pathway

  3. Oxidative-phosphorylation

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

  • Pentose phosphate shunt is the pathway that is used for the synthesis of a 5 carbon molecules such as ribose and deoxyriose which can be used for the synthesis of nucleotides, no ATP is produced during this reaction.
  • EMP pathway is the glycolysis process where 2 ATP are produced at the end of the reaction.
  • Oxidative phosporylation is the pathway that is used to reduce the NADH and FADH for the formation of ATP
  • And photosynthesis is the pathway in the plant that is used for the production of the carbohydrates that are used in the catabolic pathway for the synthesis of the ATP in cellular respiration.
  • Therefore the correct answer is option is 'Pentose phosphate shunt'.