Tag: cam cycle

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Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

Select the incorrect statement from the following.

  1. C4 pathway for CO$ _2$ fixation were discovered by Hatch and Slack.
  2. CO$ _2$ is essential for photosynthesis.

  3. Addition of sodium carbonate in water retards photosynthetic rate in Vallisneria.

  4. Phloem is the principal pathway for translocation of solutes.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Sodium bicarbonate acts as a source of carbon-dioxide to the plant which helps in the production of carbohydrates during photosynthesis acting as the carbon source for the same. Its addition in the water increases the photosynthetic rate in Vallisneria. Thus, CO2 is essential for photosynthesis. 
The C4 pathway is also known as the Hatch and Slack pathway in the name of their discoverers Hatch and Slack.
Phloem in plants acts the pathway for transport of plant solutes and metabolites whereas xylem acts as the pathway for transport of water.
The correct answer is 'addition of sodium carbonate in water retards photosynthesis rate in Vallisneria'.
Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In a CAM plant, the concentration of organic acid

  1. Increases during the day.

  2. Decreases or increases during the day.

  3. Increases during night.

  4. Decreases during any time.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Crassulacean acid metabolism 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. The $CO _2$ is stored as the four-carbon acid malate and then used during photosynthesis during the day. As photosynthesis occurs during night, the concentration of organic acid, which is the product of photosynthesis increases during night. Thus, option C is correct answer.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

Who coined the term CAM?

  1. Benson

  2. Ranson and Thomas

  3. Benson and Thomas

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

Ranson and Thomas coined the term CAM (Crassulacean Acid Metabolism)  in 1940. CAM pathway 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.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

PEPco is associated with

  1. $C _3$ plants

  2. CAM plants
  3. $C _4$ plants

  4. Both B and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

C- Plants using PEP carboxylase have a ring of specialised cells, called bundle sheath cells, around the vascular bundles (veins) in their leaves. PEP carboxylase forms part of a carbon dioxide pumping mechanism. Oxaloacetate can be converted to malate in the leaf mesophyll cells and transferred to the bundle sheath cells. Here 4 carbon malate is converted to 3 carbon pyruvate, yielding carbon dioxide and reducing NADP to NADPH for use in the C3 carbon fixing cycle.

B- CAM are C4 plants that fix carbon dioxide during the night. They store it as 4 carbon malate, releasing carbon dioxide during daylight when the light-dependent reactions of photosynthesis can take place. During the night carbon dioxide enters through the open stomata and is fixed by PEP carboxylase as oxaloacetate. This is converted to malate which accumulates in cell vacuoles, giving a store of fixed carbon.

So, the correct option is 'Option D'

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In CAM plants, organic acid content

  1. Decreases during night

  2. Increases during day

  3. Increases during night

  4. Both A and B
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In CAM plants, organic acid content increases during the night because the stomata remain open at the night and close during the daytime to conserve water. When stomata are open during the night, carbon dioxide is fixed by the action of phosphoenolpyruvate carboxylase to malic acid, this is called as acidification. During daytime, when the stomata are closed, malic acid is converted to pyruvic acid and carbon dioxide, this is called as deacidification. Hence acid concentration increases at night and decreases at daytime. So, the correct answer is 'Increases during night'.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

CAM plants belong to .......... family.

  1. Malvaceae

  2. Crassulaceae

  3. Trapaceae

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

CAM stands for crassulacean acid metabolism because it was first studied in members of the plant family Crassulaceae (Bryophyllum). CAM is the fixation of carbon dioxide by plants in arid condition. In normal conditions, the opening of the stomata is always connected with the large losses of water. To inhibit this loss during intense sunlight, CAM plants have developed a mechanism which allows the uptake of carbon dioxide during the night. They are more common than C$ _4$ plants and include cacti and a wide variety of other succulent plants. So, the correct answer is 'Crassulaceae'.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

Sunken stomata are usually found in

  1. Phanerogams
  2. $C _3$ plants

  3. CAM plants

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

A) Phanerogams are seed bearing plants like Gymnosperms and Angiosperms. They have prominent stomata.

B) ${ C } _{ 3 }$ plants have bean shaped stomata present on their surface.
C) CAM plants have sunken stomata to reduce the loss of water through transpiration.
D) Insectivorous plants do not have stomata.
So the correct answer is 'CAM plants'.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

The common feature in CAM and $C _4$ plants is

  1. Stomata open only during night

  2. Acid concentration increases during night
  3. Both $C _3$ and $C _4$ pathways occur

  4. Having Kranz anatomy
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A) Stomata are open both during the day and night in ${ C } _{ 4 }$ plants, but open only at night in CAM plants.

B) The acid in ${ C } _{ 4 }$ plants decreases at night.
C) In both CAM and ${ C } _{ 4 }$ plants, ${ C } _{ 4 }$ pathway takes place followed by ${ C } _{ 3 }$ pathway.
D) Only ${ C } _{ 4 }$ plants have Kranz anatomy.
So the correct answer is 'Both ${ C } _{ 3 }$ and ${ C } _{ 4 }$ pathways occur'.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

Which of the following is a CAM plant?

  1. Maize

  2. Sugarcane

  3. Agave

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

Crassulacean acid metabolism 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.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

Kranz type of anatomy is found in 

  1. $C _{3}$ plants
  2. $C _{2}$ plants
  3. $C _{4}$ plants

  4. CAM plant
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • $C _4$ photosynthesis incorporates novel leaf anatomy, metabolic specializations, and modified gene expression.
  • Plants that utilize this pathway typically possess a distinctive Kranz leaf anatomy, consisting of two photosynthetic cell types.
  • Their vascular bundles are surrounded by two rings of cells; the inner ring, called bundle sheath cells, contains starch-rich chloroplasts lacking grana, which differ from those in mesophyll cells present as the outer ring.
  • This structural framework allows for the compartmentalization and functional separation of two sets of carboxylation and decarboxylation reactions.
    Hence, the correct answer is C.