Tag: c3, c4 and cam plants

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Questions Related to c3, c4 and cam plants

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
A Correct answer
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
Kranz anatomy is not exhibited by which of the following plants?

  1. Maize

  2. Sorghum

  3. Sugarcane

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

Kranz anatomy is observed in $C _4$ grasses like Maize, Sorghum and Sugarcane. This is to reduce the inefficiencies of RuBisCO that can catalyse the reaction with $O _2$ rather than $CO _2$ resulting in photorespiration than photosynthesis. To overcome this, $CO _2$ is first as a four carbon compound and then made available to RuBisCO, This is a spatial and temporal separation of reactions into bundle sheath cells and a ring of mesophyll cells surrounding the bundle sheath. Sunflower has only $C _3$ cycle of photosynthesis and does not exhibit Kranz anatomy.

So, the correct answer is 'Sunflower'


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'.