Cam plants - class-XI
Description: cam plants | |
Number of Questions: 45 | |
Created by: Priya Bakshi | |
Tags: photosynthesis photosynthesis in higher plants biology botany |
An example of CAM plant is
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Black Nightshade (Solanum nigrum)
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Lemon Grass (Cymbopogon flexuosus)
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Sugarbeet (Beta vulgaris)
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Snake Plant (Sanseveria trifasciata)
Certain plants which have Crassulacean Acid Metabolism (CAM) are known as CAM plants. They have scotoactive stomata. It means their stomata remain open during the night. It is the characteristic feature of CAM plants. These plants fix carbon dioxide during the night but form sugars only during the day when RuBisCO is active. Sedum, Kalanchoe, Pineapple, Opuntia, Snake plant are the examples of CAM plants. These plants also perform double carbon dioxide fixation. The carbon dioxide acceptor in CAM plants is Phosphoenol pyruvic acid (PEP) during the night and Ribulose bisphosphate is carbon dioxide acceptor during the daytime. The first stable product in case of CAM plants is Oxalo acetic acid (OAA).
In CAM plants, $CO _2$ required for photosynthesis enters the plant body during
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Daytime when the stomata are open.
-
Night when the hydathodes are open.
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Daytime through the lenticels.
-
Nights through the stomata which are kept open.
CAM plants are those plants whose stomata open at night so that they can fix carbon-dioxide in the form of organic acids because these plants are adapted to grow in arid conditions. They accumulate carbon dioxide at night in vacuoles whereas in day time malic acid in transported to chloroplasts where it is again converted into carbon dioxide for photosynthesis.
Which one of the following is a CAM plant?
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Maize
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Kalanchoe
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Sugarcane
-
Jowar
The carbon dioxide acceptor in CAM plants is
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Malic acid
-
Oxalo-acetic acid
-
Pyruvic acid
-
Phosphoenol pyruvic acid
Certain plants which have Crassulacean Acid metabolism (CAM) are known as CAM plants. They have scotoactive stomata. These plants fix carbon dioxide during the night but form sugars only during the day when RuBisCO is active. sedum, kalanchoe, pineapple, opuntia are the examples of CAM plants. These plants also perform double carbon dioxide fixation. The carbon dioxide acceptor in CAM plants is Phosphoenol pyruvic acid (PEP) during the night and Ribulose bisphosphate is carbon dioxide acceptor during day time. The first stable product in case of CAM plants is Oxalo acetic acid (OAA).
In CAM plants, $CO _2$ required for photosynthesis enters the plant during
-
Daytime when stomata are open
-
Night when stomata are open
-
Night when hydathodes are open
-
Daytime through lenticels
Certain plants which have Crassulacean Acid Metabolism (CAM) are known as CAM plants. They have scotoactive stomata. $CO _{2}$ required for photosynthesis enters the plant during the night when stomata are open. Then, this carbon dioxide is fixed during the night but form sugars only during the day when RuBisCO is active. Sedum, Kalanchoe, Pineapple, Opuntia are the examples of CAM plants. These plants also perform double carbon dioxide fixation. The carbon dioxide acceptor in CAM plants is Phosphoenol pyruvic acid (PEP) during the night and Ribulose bisphosphate is carbon dioxide acceptor during the daytime. The first stable product in case of CAM plants is Oxalo acetic acid (OAA).
Which one is feature of Kranz anatomy
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Well developed chloroplasts in bundle sheath cells
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Rudimentary chloroplasts in bundle sheath cells
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Chloroplasts in epidermal cells
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Chloroplasts in vascular tissue
Kranz anatomy is found in leaves of $C _{4}$ plants. The $C _{4}$ pathway requires the presence of two types of cells i.e. mesophyll cells and bundle sheath cells. The particularly large cells around the vascular bundles of $C _{4}$ plants are called bundle sheath cells, these cells may form several layers around the vascular bundles, they are characterized by having a large number of well-developed chloroplasts, grana are absent, thick walls impervious to gaseous exchange and no extracellular spaces. This special anatomy of leaves of the $C _{4}$ plants is called Kranz anatomy. 'Kranz' means wreath and is a reflection of the arrangement of cells.
Kranz anatomy occurs in
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Leaves
-
Stem
-
Flower
-
Seed
Kranz anatomy is found in leaves of $C _{4}$ plants. The $C _{4}$ pathway requires the presence of two types of cells i.e., mesophyll cells and bundle sheath cells. The particularly large cells around the vascular bundles of $C _{4}$ plants are called bundle sheath cells, these cells may form several layers around the vascular bundles, they are characterized by having a large number of chloroplasts, grana are absent, thick walls impervious to gaseous exchange and no extracellular spaces. This special anatomy of leaves of the $C _{4}$ plants is called Kranz anatomy. 'Kranz' means wreath and is a reflection of the arrangement of cells.
Which one of the following is a CAM plant
-
Maize
-
Kalanchoe
-
Sugarcane
-
Jowar
Certain plants which have Crassulacean Acid Metabolism (CAM) are known as CAM plants. They have scotoactive stomata. It means their stomata remain open during the night. It is the characteristic feature of CAM plants. These plants fix carbon dioxide during the night but form sugars only during the day when RuBisCO is active. Sedum, Kalanchoe, Pineapple, Opuntia, Snake plant are the examples of CAM plants. These plants also perform double carbon dioxide fixation. The carbon dioxide acceptor in CAM plants is Phosphoenol pyruvic acid (PEP) during the night and Ribulose bisphosphate is carbon dioxide acceptor during the daytime. The first stable product in case of CAM plants is Oxalo acetic acid (OAA).
Stomata remain open at night in
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$C _3$ plants
-
$C _4$ plants
-
CAM plants
-
Hydrophytic plants
Certain plants which have Crassulacean Acid Metabolism (CAM) are known as CAM plants. They have scotoactive stomata, i.e. stomata remain open in night. These plants fix carbon dioxide during the night but form sugars only during the day when RuBisCO is active. Sedum, Kalanchoe, Pineapple, Opuntia are the examples of CAM plants. These plants also perform double carbon dioxide fixation. The carbon dioxide acceptor in CAM plants is Phosphoenol pyruvic acid (PEP) during the night and Ribulose bisphosphate is carbon dioxide acceptor during the daytime. The first stable product in case of CAM plants is Oxalo acetic acid (OAA).
In Kranz anatomy, the bundle sheath cell have
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Thick walls, many intercellular spaces and no chloroplasts
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Thin walls, no intercellular spaces and large number of chloroplasts
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Thick walls, no intercellular spaces and large number of chloroplasts
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Thin walls, many intercellular spaces and several chloroplasts
Which of the following statements is characteristic feature of CAM plants
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Release oxygen during day
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Release oxygen during night
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Open their stomata during night
-
Do not respire during day
Certain plants which have Crassulacean Acid metabolism (CAM) are known as CAM plants. They have scotoactive stomata. Their stomata remain open during night. It is characteristic feature of CAM plants. These plants fix carbon dioxide during night but form sugars only during day when RuBisCO is active. Sedum, Kalanchoe, Pineapple, Opuntia are the examples of CAM plants. These plants also perform double carbon dioxide fixation. The carbon dioxide acceptor in CAM plants is Phosphoenol pyruvic acid (PEP) during night and Ribulose bisphosphate is carbon dioxide acceptor during day time. The first stable product in case of CAM plants is Oxalo acetic acid (OAA).
Succulents perform
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$C _4$ cycle
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CAM
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$C _3$ cycle
-
All of the above
CAM plants are usually the succulents (eg : cacti, agave) as they are efficient at storing water due to the climates they live in i.e., dry and arid. The leaves of succulent plants are thick, contains moisture and have a coat of wax to reduce evaporation. During the day, the plants close their stoma to prevent the loss of water and open it at night to absorb the carbon dioxide from the surrounding atmosphere. The carbon dioxide is later converted into malate, which is used in the process of photosynthesis (via the calvin cycle) when the daylight returns.
In CAM plants, photophosphorylation occurs in
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Bundle sheath cell, during night
-
Mesophyll cell, during day time
-
Mesophyll cell, during night
-
Bundle sheath cell, during day time
In CAM plants, photophosphorylation occurs in bundle sheath cell during night. Hence, stomata is open during night in order to fix the carbon dioxide. During night, a four carbon acid is produced when stomata are open. RuBisCo enzyme fixes carbon during the day time during the light reactions. Examples of plants that show CAM photosynthesis are cactus and pineapple.
C A M photosynthesis occurs in plants with
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Thin green leaves with reticulate venation
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Thin green leaves with parallel venation
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Fleshy green leaves
-
Thin coloured leaves
CAM (Crassulacean Acid Metabolism) photosynthesis is found in most desert plants, particularly the succulents (plants that store water in thick, fleshy leaves). CAM plants keep their stomata closed during the day to conserve water. At night, the stomata open to allow CO$ _{2}$ to enter. CO$ _{2}$ is incorporated into organic acids which are then stored within the mesophyll cells. During the day, CO$ _{2}$ is released from the organic acids to supply the Calvin Cycle. Thus, CAM photosynthesis occurs in fleshy green leaves and not in thin green leaves with reticulated venation or Thin green leaves with parallel or thin colored leaves. Thus, option C is correct and other options are incorrect.
In sugarcane plant, ${^{14}CO _2}$ is fixed in malic acid, the enzyme that fixes ${C O _2}$ in this reaction is
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Ribulose biphosphate carboxylasc
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Phosphoenol pyruvic acid carboxylase
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Ribulose phosphate kinase
-
Fructose phosphatase
Phosphoenol pyruvate is formed from the decarboxylation of oxloacetate and hydrolysis of one guanosine triphosphate molecule. This reaction is catalyzed by the enzyme phosphoenolpyruvate carboxylase. This reaction is a rate limiting step in gluconeogenesis.
GTP + Oxaloacetate -----> GDP + Phosphoenolpyruvate + $CO _2$.
CAM helps the plants in
-
Reproduction
-
Conserving water
-
Secondary growth
-
Disease resistance
Certain plants especially succulents which grow under extremely xerophytic conditions, fix atmospheric carbon dioxide in the dark. Since the process was first observed in the plants belonging to family Crassulaceae such as Bryophyllum, Kalanchoe, Sedum etc., it was termed crassulacean acid metabolism (CAM). Such plants are known as CAM plants. The most characteristic feature of these plants is that their stomata remain open at night but closed during the day. Thus, CAM is a kind of adaptation in succulents to carry out photosynthesis without much loss of water. This helps in conserving water in these plants.
CAM plants are mainly
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Succulent xerophyte
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Hydrophytes
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Epiphyted
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None of the above
CAM plants are mainly succulent xerophytes. Besides C3 and C4 cycles, Crassulacean acid metabolism is a third mechanism for fixing carbon dioxide. It is found not only in members of the family Crassulaceae eg., Kalanchoe, Sedum, Crassula, but also in the members of family Cactaceae example Opuntia. Besides it also occurs in some members of Liliaceae, Orchidaceae, Bromeliaceae, Euphorbia sp and pteridophytes like Isoetes. In CAM plants the stomata are open at night and during day time the stomata remain close.
In the mesophyll cells of CAM plants, $CO _{2}$ fixation during the day occurs through
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RuBP oxygenase
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PEP carboxylase
-
RuBP carboxylase
-
Both RuBP carboxylase and PEP carboxylase
CAM photosynthesis is a carbon fixation pathway present in some plants, such as desert plants. These plants fix carbon dioxide during night, storing it as the four carbon acid malate. The malate is then reduced to a three carbon compound oxaloacetate and the carbon dioxide. This carbon dioxide is released during the day, where it is concentrated around the enzyme RuBP carboxylase and increases the efficiency of photosynthesis. The carboxylating enzyme used during day is RuBP carboxylase and during the night its PEP carboxylase.
Answer is option C.
The source of $CO _{2}$ for photosynthesis in the CAM plants is
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3-PGA.
-
Malic acid.
-
Oxaloacetic acid.
-
Pyruvate.
In CAM plants there is temporal separation between initial carbon dioxide fixation and Calvin cycle. In these plants, during night time the stomata are open and atmospheric carbon dioxide is fixed into organic acids like malic acid. The organic acids are stored in cell vacuoles during night time. During day time the stomata are closed and organic acids are decarboxylated to release carbon dioxide. The released carbon dioxide is fixed by the RuBisCO and usual reactions of the Calvin cycle.
Kranz anatomy can be observed in leaves of ______________.
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Sorghum
-
Spinach
-
Mustard
-
Tulip
- Kranz anatomy is a special structure of leaves in C4 PLANTS e.g. maize, sugarcane, sorghum, and millets.
- Mustard and Spinach belongs to C3 plants.
- Tulip is an example of a CAM plant.
So, the correct answer is option A, Sorghum
Select the incorrect statement from the following.
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C4 pathway for CO$ _2$ fixation were discovered by Hatch and Slack.
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CO$ _2$ is essential for photosynthesis.
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Addition of sodium carbonate in water retards photosynthetic rate in Vallisneria.
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Phloem is the principal pathway for translocation of solutes.
In a CAM plant, the concentration of organic acid
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Increases during the day.
-
Decreases or increases during the day.
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Increases during night.
-
Decreases during any time.
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.
Who coined the term CAM?
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Benson
-
Ranson and Thomas
-
Benson and Thomas
-
Arnon
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.
PEPco is associated with
-
$C _3$ plants
-
CAM plants
-
$C _4$ plants
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Both B and C
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.
In CAM plants, organic acid content
-
Decreases during night
-
Increases during day
-
Increases during night
-
Both A and B
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'.
CAM plants belong to .......... family.
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Malvaceae
-
Crassulaceae
-
Trapaceae
-
Orchidaceae
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'.
Sunken stomata are usually found in
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Phanerogams
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$C _3$ plants
-
CAM plants
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Insectivorous plants
A) Phanerogams are seed bearing plants like Gymnosperms and Angiosperms. They have prominent stomata.
C) CAM plants have sunken stomata to reduce the loss of water through transpiration.
The common feature in CAM and $C _4$ plants is
-
Stomata open only during night
-
Acid concentration increases during night
-
Both $C _3$ and $C _4$ pathways occur
-
Having Kranz anatomy
A) Stomata are open both during the day and night in ${ C } _{ 4 }$ plants, but open only at night in CAM plants.
C) In both CAM and ${ C } _{ 4 }$ plants, ${ C } _{ 4 }$ pathway takes place followed by ${ C } _{ 3 }$ pathway.
So the correct answer is 'Both ${ C } _{ 3 }$ and ${ C } _{ 4 }$ pathways occur'.
Which of the following is a CAM plant?
-
Maize
-
Sugarcane
-
Agave
-
Mango
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.
Kranz type of anatomy is found in
-
$C _{3}$ plants
-
$C _{2}$ plants
-
$C _{4}$ plants
-
CAM plant
- $C _4$ 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.
In CAM cycle, during the formation of malic acid, stomata remains
-
Open
-
Closed
-
Semi open
-
Always closed
CAM method 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 carbon dioxide is then stored as a four-carbon acid, malate, and then used during photosynthesis during the day. The pre-collected CO2 is concentrated around the enzyme RuBisCO, increasing photosynthetic efficiency.
In maximum plants, stomata open during day and closed at night. Its exception is
-
Crassulacean acid metabolism plants
-
$C _{3}$ plants
-
$C _{4}$ plants
-
None of the above
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. The pre-collected $CO _2$ is concentrated around the enzyme RuBisCO, increasing photosynthetic efficiency.
CAM helps the plants in
-
Reproduction
-
Secondary growth
-
Conserving water
-
Disease resistance
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.
-
$2$ ATP molecules
-
$8$ ATP molecules
-
$3$ ATP molecules
-
$4$ ATP molecules
$CO _{2} : NADPH _{2} : ATP$ ratio for $C _{4}$ plants is
-
$1 : 2 : 3$
-
$2 : 3 : 4$
-
$1 : 2 : 5$
-
$1 : 5 : 10$
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
Read the given statements and select the correct option.
Statement 1 : Crassulacean acid metabolism occurs in succulent plants which grow in xeric conditions.
Statement 2 : Stomata are generally sunken in succulent plants.
-
Both statements are correct
-
Statement 1 s correct but statement 2 is incorrect.
-
Statement 1 is incorrect but statement 2 is correct.
-
Both statement are incorrect.
Crassulacean acid metabolism is a mechanism of photosynthesis involving double fixation of $CO _2$ which occurs in succulents belonging to Crassulaceae, Cacti, Euphorbias and some other plants of dry habitats. Here, the stomata remains closed during the daytime and opens only at night, e.g Sedum,Kalanchoe,Opuntia. Sunken stomata are deep seated stomata in which subsidiary cells lie above the guard cells. So, the correct answer is 'Both statements are correct'.
Internal source of CO2 in CAM plants is
-
Oxaloacetic acid
-
Malic acid
-
RUBP
-
PEPA
In CAM plants, $ C{ O } _{ 2 } $ acceptor is
-
RuBP
-
PEP
-
OAA
-
PGA
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:
- CO$ _2$ uptake takes place mainly at night
- stomata are open during the night and closed during the day when CO$ _2$ uptake is mostly negligible.
- Malate accumulates at night by carboxylation of PEP.
- Decarboxylation of malate during the day yields CO$ _2$ which is fixed up by RuBP carboxylase.
In CAM plants the site of light reaction and glucose synthesis are
-
Mesophyll, Bundle seath
-
Bundle sheath, Mesophyll
-
Mesophyll, Mesophyll
-
Bundle seath, Bundle seath
Which of the following metabolic cycle is an adaptation against Glycolate metabolism?
-
Crassulacean acid metabolism
-
Co-operative photosynthesis
-
Reductive pentose phosphate pathway
-
Photochemical reaction
In CAM plants, the acceptor of ${CO _2}$ is
-
Pyruvic acid.
-
Oxaloacetate.
-
Phosphoenol pyruvate.
-
Nucleic acid.
- 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'.
The plant adaptation not suitable for hot and dry climates is
I. CAM
II. Mycorrhizae
III. ${C} _{4}$ photosynthesis
-
I only
-
II only
-
I and II
-
I and III
-
I, II, and III
Spatial separation of carbon dioxide fixation and RUBISCO activity in mesophyll and bundle sheath cells of $C _4$ plants respectively avoids photorespiration by concentrating $CO _2$ in bundle sheath cells to scale down the oxygenase activity of RUBISCO and increase the RUBISCO efficiency. The increased RUBISCO efficiency allows higher rates of photosynthesis even when stomata are closed for the longer time as well as reduces photorespiration and water loss. CAM plants reduce water loss by opening the stomata at night only. Mycorrhizae are the symbiotic fungi that reside in roots of higher plants and increase soil fertility by nitrogen fixation; it does not impart any adaptive feature to plant to cope with hot and dry conditions.
The internal source of $C{ O } _{ 2 }$ in CAM plants is
-
Oxalo-acetic acid
-
Malic acid
-
RUBP
-
PEPA
In which of the following respects the photosynthetic adaptations of $C _4$ plants and CAM plants are similar?
-
In both cases, stomata normally close during the day
-
Both types of plants make their sugar without the Calvin cycle
-
In both cases, an enzyme other than rubisco carries out the first step in carbon fixation
-
Neither $C _4$ plants nor CAM plants have grana in their chloroplasts
$C _4$ 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 $O _2$.
In kranz anatomy, the bundle sheath cells have
-
thin walls, many intercellular spaces and no chloroplasts
-
thick walls, no intercellular spaces and large number of chloroplasts
-
thin walls, no intercellular spaces and several chloroplasts
-
thick walls, many intercellular spaces and few chloroplasts.