All questions of Plant Reproduction for Grade 9 Exam
The splitting of water molecule is take place inside
a)Outer membraneb)Lumenc)Stromad)Inner membrane Correct answer is option 'B'. Can you explain this answer?
|
|
Vibhor Goyal answered |
Splitting of water takes place near PS II, located in the inner side of the thylakoid membrane.
Splitting of water releases oxygen in the atmosphere and generates a proton gradient across the thylakoid membrane.
The splitting of water molecules is associated with- a)PS II
- b)PS I
- c)Cyclic phosphorylation
- d)Non-cyclic phosphorylation
Correct answer is option 'A'. Can you explain this answer?
The splitting of water molecules is associated with
a)
PS II
b)
PS I
c)
Cyclic phosphorylation
d)
Non-cyclic phosphorylation
|
Swara Sarkar answered |
This is achieved by electrons available due to splitting of water. The splitting of water is associated with the PS II; water is split into H+, [O] and electrons.
In the half-leaf experiment of photosynthesis, KOH solution is used because- a)It provides O2 to the leaf.
- b)It provides moisture to the leaf.
- c)It helps in CO2 fixation.
- d)It absorbs CO2.
Correct answer is option 'D'. Can you explain this answer?
In the half-leaf experiment of photosynthesis, KOH solution is used because
a)
It provides O2 to the leaf.
b)
It provides moisture to the leaf.
c)
It helps in CO2 fixation.
d)
It absorbs CO2.
|
Krishna Iyer answered |
KOH (Potassium Hydroxide) absorbs carbon dioxide. The leaf inside the bottle containing KOH solution does not become blue-black when compared with the leaf which is exposed to atmospheric air. This shows that carbon dioxide is necessary for photosynthesis.
The dark reaction in photosynthesis is called so because- a)It does not depend on light energy.
- b)It can occur in dark also.
- c)It cannot occur during day light.
- d)It occurs more rapidly at night.
Correct answer is option 'A'. Can you explain this answer?
The dark reaction in photosynthesis is called so because
a)
It does not depend on light energy.
b)
It can occur in dark also.
c)
It cannot occur during day light.
d)
It occurs more rapidly at night.
|
Mansi Ahuja answered |
Explanation:
Photosynthesis is a process by which green plants and some other organisms use sunlight, carbon dioxide, and water to synthesize foods with the help of chlorophyll pigment. The process of photosynthesis is divided into two parts - light-dependent reactions and light-independent reactions.
The light reactions occur in the thylakoid membranes of the chloroplasts and involve the absorption of light energy by the pigments like chlorophyll and the conversion of that energy into chemical energy in the form of ATP and NADPH. The dark reactions, on the other hand, occur in the stroma of the chloroplasts and are also known as the Calvin cycle.
Dark reactions in photosynthesis:
The dark reactions or the light-independent reactions in photosynthesis are so called because they do not require the presence of light energy to occur. These reactions can occur in the absence of light, but they do require the products of the light-dependent reactions, i.e., ATP and NADPH, to proceed. The dark reactions involve the fixation of carbon dioxide into organic molecules like glucose, which can be used as a source of energy by the plant.
The dark reactions also involve the enzyme RuBisCO, which is responsible for catalyzing the reaction between carbon dioxide and ribulose 1,5-bisphosphate (RuBP). The reaction produces two molecules of 3-phosphoglycerate, which is then converted into other organic molecules like glucose and other carbohydrates.
Conclusion:
In conclusion, the dark reactions in photosynthesis are called so because they do not depend on light energy to occur. They can occur in the absence of light, but they do require the products of the light-dependent reactions to proceed. The dark reactions involve the fixation of carbon dioxide into organic molecules and are essential for the synthesis of glucose and other carbohydrates, which serve as a source of energy for the plant.
Photosynthesis is a process by which green plants and some other organisms use sunlight, carbon dioxide, and water to synthesize foods with the help of chlorophyll pigment. The process of photosynthesis is divided into two parts - light-dependent reactions and light-independent reactions.
The light reactions occur in the thylakoid membranes of the chloroplasts and involve the absorption of light energy by the pigments like chlorophyll and the conversion of that energy into chemical energy in the form of ATP and NADPH. The dark reactions, on the other hand, occur in the stroma of the chloroplasts and are also known as the Calvin cycle.
Dark reactions in photosynthesis:
The dark reactions or the light-independent reactions in photosynthesis are so called because they do not require the presence of light energy to occur. These reactions can occur in the absence of light, but they do require the products of the light-dependent reactions, i.e., ATP and NADPH, to proceed. The dark reactions involve the fixation of carbon dioxide into organic molecules like glucose, which can be used as a source of energy by the plant.
The dark reactions also involve the enzyme RuBisCO, which is responsible for catalyzing the reaction between carbon dioxide and ribulose 1,5-bisphosphate (RuBP). The reaction produces two molecules of 3-phosphoglycerate, which is then converted into other organic molecules like glucose and other carbohydrates.
Conclusion:
In conclusion, the dark reactions in photosynthesis are called so because they do not depend on light energy to occur. They can occur in the absence of light, but they do require the products of the light-dependent reactions to proceed. The dark reactions involve the fixation of carbon dioxide into organic molecules and are essential for the synthesis of glucose and other carbohydrates, which serve as a source of energy for the plant.
The C4 plants show higher rate of photosynthesis in- a)Optimum temperature
- b)High temperature
- c)Absence of temperature
- d)Low temperature
Correct answer is option 'B'. Can you explain this answer?
The C4 plants show higher rate of photosynthesis in
a)
Optimum temperature
b)
High temperature
c)
Absence of temperature
d)
Low temperature
|
Shreya Saini answered |
C4 planets show higher rate of photosynthesis in higher temperatures because there is no energy loss in photorespiration in these plants, i.e.at high temperature they show full efficiency of production.
Which of the following do not undergo anysecondary growth?
- a)Dicotyledonous stem
- b)Monocotyledonous root
- c)Monocotyledonous stem
- d)Both (B) and (C)
Correct answer is option 'D'. Can you explain this answer?
Which of the following do not undergo anysecondary growth?
a)
Dicotyledonous stem
b)
Monocotyledonous root
c)
Monocotyledonous stem
d)
Both (B) and (C)
|
Prasenjit Pillai answered |
Monocotyledonous roots and stems generally do not undergo secondary growth:
-
Monocotyledonous rootsMonocot roots do not undergo secondary growth because they lack vascular cambium, which is found in the vascular bundle between the xylem and phloem.
-
Monocotyledonous stemsMonocot stems do not undergo secondary growth, but they can increase in girth. This is called anomalous thickening and does not result in the development of secondary xylem and phloem
The Calvin cycle leads to reduction of- a)RUBP
- b)RUMP
- c)O2
- d)CO2
Correct answer is option 'D'. Can you explain this answer?
The Calvin cycle leads to reduction of
a)
RUBP
b)
RUMP
c)
O2
d)
CO2
|
Rajat Kapoor answered |
In fixation, the first stage of the Calvin cycle, light-independent reactions are initiated; CO2 is fixed from an inorganic to an organic molecule. In the second stage, ATP and NADPH are used to reduce 3-PGA into G3P; then ATP and NADPH are converted to ADP and NADP+, respectively.
Who described the first action spectrum for photosynthesis?- a)T. W. Engelmann
- b)Cornelius van Niel
- c)Joseph Priestley
- d)Julius von Sachs
Correct answer is option 'A'. Can you explain this answer?
Who described the first action spectrum for photosynthesis?
a)
T. W. Engelmann
b)
Cornelius van Niel
c)
Joseph Priestley
d)
Julius von Sachs
|
Arun Khanna answered |
Engelmann used a prism to split light into its spectral components, and then illuminated a green alga, Cladophora, placed in a suspension of aerobic bacteria. The bacteria were used to detect the sites of oxygen evolution.
He observed that bacteria mainly accumulated in the region of blue and red light of the split spectrum, thus giving the first action spectrum of photosynthesis.
In PSI, the reaction centre the chlorophyll a has an absorption peak at- a)780nm
- b)700nm
- c)680nm
- d)800nm
Correct answer is option 'B'. Can you explain this answer?
In PSI, the reaction centre the chlorophyll a has an absorption peak at
a)
780nm
b)
700nm
c)
680nm
d)
800nm
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|
Vartika Shukla (NEET Aspirant) answered |
In PS-I, the reaction centre chlorophyll a has an absorption peak at 700 nm, hence, is called P 700 while in PS-H, it has absorption maxima at 680 nm, so is called P 680.
so the correct answer is b) 700nm
so the correct answer is b) 700nm
For fixing one molecule of CO2 in Calvin cycle, required- a)3ATP+2NADPH2
- b)3ATP+1NADPH2
- c)2ATP+3NADPH2
- d)3ATP+3NADPH2
Correct answer is option 'A'. Can you explain this answer?
For fixing one molecule of CO2 in Calvin cycle, required
a)
3ATP+2NADPH2
b)
3ATP+1NADPH2
c)
2ATP+3NADPH2
d)
3ATP+3NADPH2
|
Aashna Mukherjee answered |
Fixing of one molecule of carbon dioxide in Calvin cycle require 3 ATP and 2 NADPH2 as the source of energy. One NADPH2 molecule produce 3 molecules of ATP.
The casparian thickening occurs in the cells of
- a)Pericycle of root
- b)Endodermis of stem
- c)Endodermis of root
- d)Pericycle of stem
Correct answer is option 'C'. Can you explain this answer?
The casparian thickening occurs in the cells of
a)
Pericycle of root
b)
Endodermis of stem
c)
Endodermis of root
d)
Pericycle of stem
|
Aniket Chawla answered |
Casparian strips occur in the Endodermis. It is a cell wall material that is deposited in the radial and transverse walls of the endodermis of roots.
Solarisation is- a)Effect of solar light
- b)Destruction of chlorophyll
- c)Formation of chlorophyll
- d)Utilisation of sunlight
Correct answer is option 'B'. Can you explain this answer?
Solarisation is
a)
Effect of solar light
b)
Destruction of chlorophyll
c)
Formation of chlorophyll
d)
Utilisation of sunlight
|
Muskaan Dasgupta answered |
Solarisation is the process of destruction of chlorophyll due to prolonged exposure to sunlight. This phenomenon is commonly observed in plants that grow in areas with high solar radiation. Here is a detailed explanation of the process:
Explanation:
Chlorophyll is the green pigment present in the leaves of plants. It plays a crucial role in photosynthesis, which is the process by which plants convert sunlight into energy. However, prolonged exposure to sunlight can damage the chlorophyll molecules, leading to their destruction. This process is known as solarisation.
Solarisation occurs due to the following reasons:
1. High intensity of sunlight: Plants that grow in areas with high solar radiation are more prone to solarisation. This is because the intensity of sunlight in these areas is much higher than in other regions.
2. Extended exposure to sunlight: The longer a plant is exposed to sunlight, the greater the damage to its chlorophyll molecules. This is why solarisation is more common during the summer months, when the days are longer and the sun is more intense.
Effects of solarisation:
1. Reduced photosynthesis: Solarisation damages the chlorophyll molecules, which reduces the plant's ability to carry out photosynthesis. This can lead to stunted growth and reduced yield.
2. Loss of colour: As the chlorophyll molecules are destroyed, the leaves of the plant lose their green colour and turn yellow or brown.
3. Increased susceptibility to pests and diseases: Plants that have been solarised are more susceptible to pests and diseases, as their weakened state makes them more vulnerable to attack.
Prevention of solarisation:
1. Shade: Providing shade to the plants can reduce their exposure to sunlight and prevent solarisation. This can be done by using shade cloth or by planting the crops under trees.
2. Watering: Regular watering can help cool down the plants and reduce the damage caused by solarisation.
3. Timely harvesting: Harvesting the crops before they are fully mature can reduce their exposure to sunlight and prevent solarisation.
In conclusion, solarisation is the process of destruction of chlorophyll due to prolonged exposure to sunlight. It can have a negative impact on plant growth and yield, and can be prevented by providing shade, regular watering, and timely harvesting.
Explanation:
Chlorophyll is the green pigment present in the leaves of plants. It plays a crucial role in photosynthesis, which is the process by which plants convert sunlight into energy. However, prolonged exposure to sunlight can damage the chlorophyll molecules, leading to their destruction. This process is known as solarisation.
Solarisation occurs due to the following reasons:
1. High intensity of sunlight: Plants that grow in areas with high solar radiation are more prone to solarisation. This is because the intensity of sunlight in these areas is much higher than in other regions.
2. Extended exposure to sunlight: The longer a plant is exposed to sunlight, the greater the damage to its chlorophyll molecules. This is why solarisation is more common during the summer months, when the days are longer and the sun is more intense.
Effects of solarisation:
1. Reduced photosynthesis: Solarisation damages the chlorophyll molecules, which reduces the plant's ability to carry out photosynthesis. This can lead to stunted growth and reduced yield.
2. Loss of colour: As the chlorophyll molecules are destroyed, the leaves of the plant lose their green colour and turn yellow or brown.
3. Increased susceptibility to pests and diseases: Plants that have been solarised are more susceptible to pests and diseases, as their weakened state makes them more vulnerable to attack.
Prevention of solarisation:
1. Shade: Providing shade to the plants can reduce their exposure to sunlight and prevent solarisation. This can be done by using shade cloth or by planting the crops under trees.
2. Watering: Regular watering can help cool down the plants and reduce the damage caused by solarisation.
3. Timely harvesting: Harvesting the crops before they are fully mature can reduce their exposure to sunlight and prevent solarisation.
In conclusion, solarisation is the process of destruction of chlorophyll due to prolonged exposure to sunlight. It can have a negative impact on plant growth and yield, and can be prevented by providing shade, regular watering, and timely harvesting.
Photosynthesis take place in- a)Roots
- b)Leaves
- c)Stem
- d)Flowers
Correct answer is option 'B'. Can you explain this answer?
Photosynthesis take place in
a)
Roots
b)
Leaves
c)
Stem
d)
Flowers
|
Arnav Iyer answered |
Photosynthesis takes place only in the green parts of the plants, mainly the leaves.
The photosystem II has reaction centre 680nm absorbs- a)Violet light
- b)Blue light
- c)Red light
- d)Green light
Correct answer is option 'C'. Can you explain this answer?
The photosystem II has reaction centre 680nm absorbs
a)
Violet light
b)
Blue light
c)
Red light
d)
Green light
|
Dipanjan Chawla answered |
While PS II has a P680 reaction centre that absorbs red light at 680 nm
Who demonstrated the importance of sunlight for the process of photosynthesis?- a)Robert Hill
- b)Engelmann
- c)Jan Ingenhousz
- d)Joseph Priestley
Correct answer is option 'C'. Can you explain this answer?
Who demonstrated the importance of sunlight for the process of photosynthesis?
a)
Robert Hill
b)
Engelmann
c)
Jan Ingenhousz
d)
Joseph Priestley
|
Pooja Mehta answered |
Jan Ingenhousz is best known for his discovery of photosynthesis, the process by which green plants absorb carbon dioxide in the presence of sunlight and release oxygen. Through an ingenious series of experiments, Ingenhousz proved that plant leaves need sunlight rather than heat in order to produce oxygen.
Photorespiration does not occur in- a)C4 plants
- b)C3 plants
- c)Algae
- d)Bacteria
Correct answer is option 'A'. Can you explain this answer?
Photorespiration does not occur in
a)
C4 plants
b)
C3 plants
c)
Algae
d)
Bacteria
|
|
Awantika Gupta answered |
Photorespiration is a wastefull process because it doesn't synthesis ATP.
but in new ncert it is mentioned that the requirements of photorespiration is not known yet.
but in new ncert it is mentioned that the requirements of photorespiration is not known yet.
Which pigment absorbs the red and far red light?- a)Cytochrome
- b)Phytochrome
- c)Carotenoids
- d)Chlorophyll
Correct answer is option 'B'. Can you explain this answer?
Which pigment absorbs the red and far red light?
a)
Cytochrome
b)
Phytochrome
c)
Carotenoids
d)
Chlorophyll
|
Srishti Shah answered |
**Phytochrome**
Phytochrome is a pigment that plays a crucial role in plant growth and development. It is a photoreceptor protein that absorbs red and far-red light wavelengths. This pigment helps plants sense and respond to changes in light conditions, such as the length of the day and the quality of light.
**Structure and Absorption Spectrum**
Phytochrome exists in two interconvertible forms: the red-light absorbing form (Pr) and the far-red-light absorbing form (Pfr). When Pr absorbs red light, it is converted into Pfr, and when Pfr absorbs far-red light, it is converted back to Pr.
The absorption spectrum of phytochrome shows two peaks: one in the red region (around 660 nm) and another in the far-red region (around 730 nm). These absorption peaks allow phytochrome to efficiently absorb red and far-red light, making it the primary pigment responsible for these light wavelengths in plants.
**Functions of Phytochrome**
1. Seed Germination: Phytochrome controls the germination of seeds by sensing and responding to the presence of light. When seeds are exposed to red light, the conversion of Pr to Pfr triggers the germination process.
2. Photomorphogenesis: Phytochrome regulates various aspects of plant development, including stem elongation, leaf expansion, and branching. In the presence of red light, Pfr promotes growth and development, while in the presence of far-red light, the conversion of Pfr to Pr inhibits growth.
3. Photoperiodism: Phytochrome also plays a crucial role in regulating flowering and flowering time in plants. The ratio of red to far-red light is used by plants to determine the length of the day, which in turn affects the flowering process.
4. Shade Avoidance: Plants can detect changes in light quality and quantity and adjust their growth patterns accordingly. Phytochrome helps plants respond to shade by promoting elongation of stems and leaves, allowing them to reach for more available light.
In conclusion, phytochrome is the pigment that absorbs red and far-red light in plants. This pigment plays a vital role in various physiological processes, including seed germination, photomorphogenesis, photoperiodism, and shade avoidance. By sensing and responding to changes in light conditions, phytochrome helps plants optimize their growth and development.
Phytochrome is a pigment that plays a crucial role in plant growth and development. It is a photoreceptor protein that absorbs red and far-red light wavelengths. This pigment helps plants sense and respond to changes in light conditions, such as the length of the day and the quality of light.
**Structure and Absorption Spectrum**
Phytochrome exists in two interconvertible forms: the red-light absorbing form (Pr) and the far-red-light absorbing form (Pfr). When Pr absorbs red light, it is converted into Pfr, and when Pfr absorbs far-red light, it is converted back to Pr.
The absorption spectrum of phytochrome shows two peaks: one in the red region (around 660 nm) and another in the far-red region (around 730 nm). These absorption peaks allow phytochrome to efficiently absorb red and far-red light, making it the primary pigment responsible for these light wavelengths in plants.
**Functions of Phytochrome**
1. Seed Germination: Phytochrome controls the germination of seeds by sensing and responding to the presence of light. When seeds are exposed to red light, the conversion of Pr to Pfr triggers the germination process.
2. Photomorphogenesis: Phytochrome regulates various aspects of plant development, including stem elongation, leaf expansion, and branching. In the presence of red light, Pfr promotes growth and development, while in the presence of far-red light, the conversion of Pfr to Pr inhibits growth.
3. Photoperiodism: Phytochrome also plays a crucial role in regulating flowering and flowering time in plants. The ratio of red to far-red light is used by plants to determine the length of the day, which in turn affects the flowering process.
4. Shade Avoidance: Plants can detect changes in light quality and quantity and adjust their growth patterns accordingly. Phytochrome helps plants respond to shade by promoting elongation of stems and leaves, allowing them to reach for more available light.
In conclusion, phytochrome is the pigment that absorbs red and far-red light in plants. This pigment plays a vital role in various physiological processes, including seed germination, photomorphogenesis, photoperiodism, and shade avoidance. By sensing and responding to changes in light conditions, phytochrome helps plants optimize their growth and development.
The site in chloroplast which is responsible for trapping for light energy is- a)Grana
- b)Stroma
- c)Ribosomes
- d)Stromal lamellae
Correct answer is option 'A'. Can you explain this answer?
The site in chloroplast which is responsible for trapping for light energy is
a)
Grana
b)
Stroma
c)
Ribosomes
d)
Stromal lamellae
|
Shruti Chauhan answered |
In chloroplast there is the membranous system consisting of grana, the stroma lamellae, and the fluid stroma. There is a clear division of labour within the chloroplast. The granum is responsible for trapping the light energy.
Photosynthesis is maximum in- a)Very high light
- b)Red light
- c)Green light
- d)Continuous light
Correct answer is option 'B'. Can you explain this answer?
Photosynthesis is maximum in
a)
Very high light
b)
Red light
c)
Green light
d)
Continuous light
|
Jyoti Kapoor answered |
For the process of photosynthesis, light is abosorbed by Photosystem II which are membrane bound. Photosystem II aborbs infrared and red light (540nm-630nm) and it is for this reason that photosynthesis is highest under red light. Though blue light maybe absorbed the highest it does not activate photosynthesis, red light is.
Which of the following stages of calvin cycle are in correct order?- a)Carboxylation, reduction, regeneration
- b)Regeneration,carboxylation, reduction
- c)Regeneration,reduction,carboxylation
- d)Carboxylation,regeneration,reduction
Correct answer is option 'A'. Can you explain this answer?
Which of the following stages of calvin cycle are in correct order?
a)
Carboxylation, reduction, regeneration
b)
Regeneration,carboxylation, reduction
c)
Regeneration,reduction,carboxylation
d)
Carboxylation,regeneration,reduction
|
|
Smruti Sucharita answered |
##ncert refer kro yrr... directly Diya hua h..
Dark fixation of CO2 in CAM plants is called ocification because it produces- a)Tartaric acid
- b)Oxaloacetic acid
- c)Malic acid
- d)Formic acid
Correct answer is option 'C'. Can you explain this answer?
Dark fixation of CO2 in CAM plants is called ocification because it produces
a)
Tartaric acid
b)
Oxaloacetic acid
c)
Malic acid
d)
Formic acid
|
|
Gopikas S answered |
The principal metabolic feature of CAM plants is assimilation of CO2 at night into malic acid which is stored in the vacuole. Malate is generated in the reaction catalyzed by PEP carboxylase and PEP is, in turn, generated by degradation of starch or soluble sugars. During the day, malate is released from the vacuole and is decarboxylated to provide CO2 for fixation in the Benson–Calvin cycle behind closed stomata. Starch and sugars are then resynthesized .
The number of Oxygen molecules released per photon or quantum of light is called- a)Quantosome
- b)Net Yield
- c)Quantum Yield
- d)Quantum number
Correct answer is option 'C'. Can you explain this answer?
The number of Oxygen molecules released per photon or quantum of light is called
a)
Quantosome
b)
Net Yield
c)
Quantum Yield
d)
Quantum number
|
Anand Jain answered |
Quantum yield is the number of Oxygen molecules released per photon or quantum of light. During light reaction of photosynthesis oxygen molecules are release during photolysis.
PGA as the first CO2 fixation product was discovered in photosynthesis of- a)Angiosperm
- b)Bryophytes
- c)Algae
- d)Gymnosperm
Correct answer is option 'C'. Can you explain this answer?
PGA as the first CO2 fixation product was discovered in photosynthesis of
a)
Angiosperm
b)
Bryophytes
c)
Algae
d)
Gymnosperm
|
|
Abhiram Basu answered |
Photosynthesis and CO2 fixation
Photosynthesis is a process by which plants, algae, and some bacteria convert sunlight, carbon dioxide, and water into organic compounds and oxygen. This process is essential for life on earth as it produces the oxygen that we breathe and provides food for organisms that cannot produce their own.
CO2 fixation is the process by which carbon dioxide is transformed into an organic molecule that can be used by living organisms. This process is important because carbon dioxide is an essential component of the atmosphere, but it is not readily available to most organisms in its gaseous form.
PGA as the first CO2 fixation product
PGA (phosphoglyceric acid) is the first stable product of CO2 fixation in photosynthesis. It is formed when carbon dioxide combines with a five-carbon sugar called ribulose bisphosphate (RuBP) in a reaction catalyzed by the enzyme Rubisco (ribulose bisphosphate carboxylase/oxygenase).
Discovery of PGA
The discovery of PGA as the first CO2 fixation product was made by Melvin Calvin and his colleagues in the 1940s. They used radioactive carbon-14 to trace the movement of carbon through the photosynthetic process and discovered that PGA was the first stable product of CO2 fixation.
Source of PGA
PGA is produced in the stroma of the chloroplasts in plant cells. It is then used to make glucose and other organic compounds through a series of enzyme-catalyzed reactions known as the Calvin cycle.
Role of algae in PGA discovery
Algae played a crucial role in the discovery of PGA as the first CO2 fixation product. Algae are photosynthetic organisms that are capable of fixing carbon dioxide in a similar way to plants. They were used by Calvin and his colleagues as a model system to study photosynthesis and CO2 fixation.
Conclusion
In conclusion, PGA was discovered as the first CO2 fixation product in photosynthesis by Melvin Calvin and his colleagues in the 1940s. This discovery was made using algae as a model system and has since been confirmed in plants and other photosynthetic organisms.
Photosynthesis is a process by which plants, algae, and some bacteria convert sunlight, carbon dioxide, and water into organic compounds and oxygen. This process is essential for life on earth as it produces the oxygen that we breathe and provides food for organisms that cannot produce their own.
CO2 fixation is the process by which carbon dioxide is transformed into an organic molecule that can be used by living organisms. This process is important because carbon dioxide is an essential component of the atmosphere, but it is not readily available to most organisms in its gaseous form.
PGA as the first CO2 fixation product
PGA (phosphoglyceric acid) is the first stable product of CO2 fixation in photosynthesis. It is formed when carbon dioxide combines with a five-carbon sugar called ribulose bisphosphate (RuBP) in a reaction catalyzed by the enzyme Rubisco (ribulose bisphosphate carboxylase/oxygenase).
Discovery of PGA
The discovery of PGA as the first CO2 fixation product was made by Melvin Calvin and his colleagues in the 1940s. They used radioactive carbon-14 to trace the movement of carbon through the photosynthetic process and discovered that PGA was the first stable product of CO2 fixation.
Source of PGA
PGA is produced in the stroma of the chloroplasts in plant cells. It is then used to make glucose and other organic compounds through a series of enzyme-catalyzed reactions known as the Calvin cycle.
Role of algae in PGA discovery
Algae played a crucial role in the discovery of PGA as the first CO2 fixation product. Algae are photosynthetic organisms that are capable of fixing carbon dioxide in a similar way to plants. They were used by Calvin and his colleagues as a model system to study photosynthesis and CO2 fixation.
Conclusion
In conclusion, PGA was discovered as the first CO2 fixation product in photosynthesis by Melvin Calvin and his colleagues in the 1940s. This discovery was made using algae as a model system and has since been confirmed in plants and other photosynthetic organisms.
In sugarcane, CO2 is fixed in malic acid with the help of enzyme- a)Ribulose phosphate kinase
- b)RuBP carboxylase
- c)Fructose phosphotase
- d)PEP carboxylase
Correct answer is option 'D'. Can you explain this answer?
In sugarcane, CO2 is fixed in malic acid with the help of enzyme
a)
Ribulose phosphate kinase
b)
RuBP carboxylase
c)
Fructose phosphotase
d)
PEP carboxylase
|
|
Jay Kumar answered |
In C4 plants, Carbon dioxide is fixed in malic acid with the help of enzyme phosphoenel pyruvate (PEP). Malic acid is a four carbon compound that later change into oxyloacetic acid.
The chief pigment associated in process of photosynthesis is- a)Chlorophyll m
- b)Chlorophyll c
- c)Chlorophyll b
- d)Chlorophyll a
Correct answer is option 'D'. Can you explain this answer?
The chief pigment associated in process of photosynthesis is
a)
Chlorophyll m
b)
Chlorophyll c
c)
Chlorophyll b
d)
Chlorophyll a
|
Lavanya Menon answered |
Chlorophyll a, shows higher rate of photosynthesis. Hence, it is conclude that chlorophyll a is the chief pigment associated with photosynthesis.
The carbon in CO2 is radioactively labelled. The product in which this radioactive carbon can be found in C3 plants is
a) PGAL
b) RuBP
c) PGA
d) PEP
Correct answer is option 'C'. Can you explain this answer?
|
|
Pankaj Singh answered |
**Explanation:**
**C3 Plants:**
C3 plants are a type of plants that undergo the Calvin cycle during photosynthesis. In this cycle, the first stable compound formed is a three-carbon molecule called phosphoglycerate (PGA). C3 plants include many common crops such as wheat, rice, and soybeans.
**Radioactive Carbon in CO2:**
When carbon dioxide (CO2) is radioactively labeled, it means that one or more of the carbon atoms in the molecule have been replaced with a radioactive isotope of carbon, such as carbon-14 (^14C). This labeling allows scientists to track the movement and transformation of carbon within a biological system.
**Product of Radioactive Carbon in C3 Plants:**
In C3 plants, the product in which the radioactive carbon can be found is phosphoglycerate (PGA). This is because during the Calvin cycle, CO2 is fixed by the enzyme RuBisCo (ribulose-1,5-bisphosphate carboxylase/oxygenase) to form an unstable six-carbon compound called RuBP (ribulose-1,5-bisphosphate). This compound then breaks down into two molecules of PGA, each containing three carbon atoms.
**Explanation of Options:**
a) PGAL (phosphoglyceraldehyde): PGAL is an intermediate molecule formed during the Calvin cycle and is a product of PGA. However, it does not directly contain the radioactive carbon from CO2.
b) RuBP (ribulose-1,5-bisphosphate): RuBP is the initial compound that reacts with CO2 during the Calvin cycle, but it is not a direct product of radioactive carbon in CO2.
c) PGA (phosphoglycerate): PGA is the first stable product formed during the Calvin cycle and contains the radioactive carbon from CO2. Therefore, this is the correct answer.
d) PEP (phosphoenolpyruvate): PEP is a molecule involved in the formation of glucose during gluconeogenesis, which is not directly related to the Calvin cycle or the fixation of CO2.
**Conclusion:**
The radioactive carbon from CO2 can be found in the product phosphoglycerate (PGA) in C3 plants. This is the first stable compound formed during the Calvin cycle and contains the radioactive carbon.
**C3 Plants:**
C3 plants are a type of plants that undergo the Calvin cycle during photosynthesis. In this cycle, the first stable compound formed is a three-carbon molecule called phosphoglycerate (PGA). C3 plants include many common crops such as wheat, rice, and soybeans.
**Radioactive Carbon in CO2:**
When carbon dioxide (CO2) is radioactively labeled, it means that one or more of the carbon atoms in the molecule have been replaced with a radioactive isotope of carbon, such as carbon-14 (^14C). This labeling allows scientists to track the movement and transformation of carbon within a biological system.
**Product of Radioactive Carbon in C3 Plants:**
In C3 plants, the product in which the radioactive carbon can be found is phosphoglycerate (PGA). This is because during the Calvin cycle, CO2 is fixed by the enzyme RuBisCo (ribulose-1,5-bisphosphate carboxylase/oxygenase) to form an unstable six-carbon compound called RuBP (ribulose-1,5-bisphosphate). This compound then breaks down into two molecules of PGA, each containing three carbon atoms.
**Explanation of Options:**
a) PGAL (phosphoglyceraldehyde): PGAL is an intermediate molecule formed during the Calvin cycle and is a product of PGA. However, it does not directly contain the radioactive carbon from CO2.
b) RuBP (ribulose-1,5-bisphosphate): RuBP is the initial compound that reacts with CO2 during the Calvin cycle, but it is not a direct product of radioactive carbon in CO2.
c) PGA (phosphoglycerate): PGA is the first stable product formed during the Calvin cycle and contains the radioactive carbon from CO2. Therefore, this is the correct answer.
d) PEP (phosphoenolpyruvate): PEP is a molecule involved in the formation of glucose during gluconeogenesis, which is not directly related to the Calvin cycle or the fixation of CO2.
**Conclusion:**
The radioactive carbon from CO2 can be found in the product phosphoglycerate (PGA) in C3 plants. This is the first stable compound formed during the Calvin cycle and contains the radioactive carbon.
Aerating pores in the bark of plants is known as- a)Lenticels
- b)Stomata
- c)Air pore
- d)None of these
Correct answer is option 'A'. Can you explain this answer?
Aerating pores in the bark of plants is known as
a)
Lenticels
b)
Stomata
c)
Air pore
d)
None of these
|
Kunal Rane answered |
In plants respiratory organs in stem is called lenticels. They are located as pores in the bark of plants.
In photosynthesis, photolysis of water is used in
- a)None of the below options
- b)Oxidation of FAD
- c)Oxidation of NADP
- d)Reduction of NADP
Correct answer is option 'D'. Can you explain this answer?
In photosynthesis, photolysis of water is used in
a)
None of the below options
b)
Oxidation of FAD
c)
Oxidation of NADP
d)
Reduction of NADP
|
Arya Khanna answered |
Breaking down of water molecules in presence of sunlight during photosynthesis is called photolysis of water. During photolysis of water reduction of NADP+ into NADPH takes place.
Carbon dioxide is fixed in- a)Dark reaction
- b)Anaerobic respiration
- c)Aerobic respiration
- d)Light reaction
Correct answer is option 'A'. Can you explain this answer?
Carbon dioxide is fixed in
a)
Dark reaction
b)
Anaerobic respiration
c)
Aerobic respiration
d)
Light reaction
|
|
Afifa Aaliya answered |
Carbon dioxide fixation takes place in absence of sunlight. Dark reaction make use of these organic energy molecules ATP and NADPH. This reaction cycle is also called as Calvin benison cycle. It occurs in the stroma. It requires to fix carbon dioxide into carbohydrates.
So option " A " is correct answer.
So option " A " is correct answer.
The stroma of chloroplast contains
- a)Ribosomes
- b)Light independent reaction enzyme
- c)Light dependent reaction enzyme
- d)Chlorophyll
Correct answer is option 'B'. Can you explain this answer?
The stroma of chloroplast contains
a)
Ribosomes
b)
Light independent reaction enzyme
c)
Light dependent reaction enzyme
d)
Chlorophyll
|
|
Jyoti Kapoor answered |
Stroma, in botany, refers to the colorless fluid surrounding the grana within the chloroplast. Within the stroma are grana, stacks of thylakoids, the sub-organelles, the daughter cells, where photosynthesis is commenced before the chemical changes are completed in the stroma. Photosynthesis occurs in two stages.
Each photosystem has all the pigments forming light harvesting systemalso called as- a)Z-scheme
- b)Antennae
- c)Cytochromes
- d)Reaction centre
Correct answer is option 'B'. Can you explain this answer?
Each photosystem has all the pigments forming light harvesting systemalso called as
a)
Z-scheme
b)
Antennae
c)
Cytochromes
d)
Reaction centre
|
Abhijeet Goyal answered |
Each photosystem has all the pigments (except one molecule of chlorophyll a) forming a light harvesting system also called antennae. These pigments help to make photosynthesis more efficient by absorbing different wavelengths of light.
The essential role of air in the growth of green plants is given by- a)Julis von sach
- b)Joseph priestly
- c)Engelmann
- d)Cornelius van niel
Correct answer is option 'B'. Can you explain this answer?
The essential role of air in the growth of green plants is given by
a)
Julis von sach
b)
Joseph priestly
c)
Engelmann
d)
Cornelius van niel
|
Arpita Tiwari answered |
Joseph Priestley (1733-1804) in 1770 performed a series of experiments that revealed the essential role of air in the growth of green plants. Priestley, you may recall, discovered oxygen in1774.
In comparison to C3 cycle, the number of extra ATP molecules required in C4 cycle is- a)12
- b)18
- c)36
- d)6
Correct answer is option 'A'. Can you explain this answer?
In comparison to C3 cycle, the number of extra ATP molecules required in C4 cycle is
a)
12
b)
18
c)
36
d)
6
|
Stepway Academy answered |
It takes 12 more ATPs than C3 cycle to replenish this PEP because additional 2 ATPs are needed for every CO2 molecule fixed.
Which of the following statements are true about photosynthesis?A. In this process, solar energy is converted into chemical energy.
B. In photosynthesis, CO2 and H2O are used.
C. In photosynthesis, CO2 is released and O2 is consumed.
D. In photosynthesis, O2 is released and carbon monoxide is consumed.- a)A and B
- b)B and C
- c)C and D
- d)A and D
Correct answer is option 'A'. Can you explain this answer?
Which of the following statements are true about photosynthesis?
A. In this process, solar energy is converted into chemical energy.
B. In photosynthesis, CO2 and H2O are used.
C. In photosynthesis, CO2 is released and O2 is consumed.
D. In photosynthesis, O2 is released and carbon monoxide is consumed.
B. In photosynthesis, CO2 and H2O are used.
C. In photosynthesis, CO2 is released and O2 is consumed.
D. In photosynthesis, O2 is released and carbon monoxide is consumed.
a)
A and B
b)
B and C
c)
C and D
d)
A and D
|
|
Stepway Academy answered |
Both statements (A) and (B) are correct about photosynthesis reaction.
A. In this process, solar energy is converted into chemical energy.
B. In photosynthesis, CO2 and H2O are used to give glucose and oxygen in the presence of sunlight with the help of green pigment chlorophyll.
A. In this process, solar energy is converted into chemical energy.
B. In photosynthesis, CO2 and H2O are used to give glucose and oxygen in the presence of sunlight with the help of green pigment chlorophyll.
How many of the following constitute the stele?Vascular bundles, pericycle, endodermis, pith, cortex, epidermis- a)4
- b)3
- c)2
- d)5
Correct answer is option 'B'. Can you explain this answer?
How many of the following constitute the stele?
Vascular bundles, pericycle, endodermis, pith, cortex, epidermis
a)
4
b)
3
c)
2
d)
5
|
|
Baishali Desai answered |
Understanding the Stele
The stele is a crucial part of the plant root and stem anatomy, involved primarily in the transport of water, nutrients, and food. It is essential to differentiate which structures constitute the stele.
Components of the Stele
The stele primarily includes:
- Vascular Bundles: These are responsible for the conduction of water (xylem) and nutrients (phloem).
- Pericycle: This is the layer of cells just inside the endodermis, from which lateral roots arise.
- Endodermis: This is the innermost layer of the cortex, forming a selective barrier to regulate the flow of water and nutrients into the vascular system.
Other Structures
The following do NOT constitute the stele:
- Pith: This is central tissue found in some stems, but is not part of the stele.
- Cortex: This is the layer of ground tissue between the epidermis and the vascular tissues, also not included in the stele.
- Epidermis: This is the outer protective layer of the plant, which does not form part of the stele.
Conclusion
Thus, the correct answer is option 'B', as only three structures (vascular bundles, pericycle, and endodermis) comprise the stele. Recognizing these components is essential for understanding plant physiology, particularly in the context of nutrient and water transport.
The stele is a crucial part of the plant root and stem anatomy, involved primarily in the transport of water, nutrients, and food. It is essential to differentiate which structures constitute the stele.
Components of the Stele
The stele primarily includes:
- Vascular Bundles: These are responsible for the conduction of water (xylem) and nutrients (phloem).
- Pericycle: This is the layer of cells just inside the endodermis, from which lateral roots arise.
- Endodermis: This is the innermost layer of the cortex, forming a selective barrier to regulate the flow of water and nutrients into the vascular system.
Other Structures
The following do NOT constitute the stele:
- Pith: This is central tissue found in some stems, but is not part of the stele.
- Cortex: This is the layer of ground tissue between the epidermis and the vascular tissues, also not included in the stele.
- Epidermis: This is the outer protective layer of the plant, which does not form part of the stele.
Conclusion
Thus, the correct answer is option 'B', as only three structures (vascular bundles, pericycle, and endodermis) comprise the stele. Recognizing these components is essential for understanding plant physiology, particularly in the context of nutrient and water transport.
Conjoint type of vascular bundles are common in- a)Stems, roots and leaves
- b)Leaves and roots
- c)Stems and leaves
- d)Stems and roots
Correct answer is option 'C'. Can you explain this answer?
Conjoint type of vascular bundles are common in
a)
Stems, roots and leaves
b)
Leaves and roots
c)
Stems and leaves
d)
Stems and roots
|
Rohan Unni answered |
In conjoint type of vascular bundles,the xylem and phloem are situated at the sameradius of vascular bundles. Such vascularbundles are common in stems and leaves. Theconjoint vascular bundles usually have thephloem located only on the outer side of xylem.
Guard cells of stomata are thicker- a)In middle
- b)Outer side
- c)Inner side
- d)Both side
Correct answer is option 'C'. Can you explain this answer?
Guard cells of stomata are thicker
a)
In middle
b)
Outer side
c)
Inner side
d)
Both side
|
Ishaan Menon answered |
The cells surrounding the stomata are called guard cells. The guard cells of inner side are thicker and that of outer side is comparatively thinner.
Assertion (A): Plant tissues are classified into meristematic and permanent types, which contribute to their various functions.Reason (R):
The main functions of plant tissues include food assimilation, storage, and mechanical support.- a)If both Assertion and Reason are true and Reason is the correct explanation of Assertion
- b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
- c)If Assertion is true but Reason is false
- d)If both Assertion and Reason are false
Correct answer is option 'A'. Can you explain this answer?
Assertion (A): Plant tissues are classified into meristematic and permanent types, which contribute to their various functions.
Reason (R):
The main functions of plant tissues include food assimilation, storage, and mechanical support.
The main functions of plant tissues include food assimilation, storage, and mechanical support.
a)
If both Assertion and Reason are true and Reason is the correct explanation of Assertion
b)
If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
c)
If Assertion is true but Reason is false
d)
If both Assertion and Reason are false
|
|
Prasenjit Khanna answered |
Understanding Plant Tissues
Plant tissues are essential components of plants, classified into two main types: meristematic and permanent. Each type plays a vital role in the overall functioning of the plant.
Assertion (A) Explained
- Meristematic Tissues: These are undifferentiated cells that can divide and contribute to growth. They are found in regions of the plant that are actively growing, like tips of roots and stems.
- Permanent Tissues: These tissues are differentiated and have specific functions. They include parenchyma, collenchyma, and sclerenchyma, each serving unique roles.
Reason (R) Explained
- Functions of Plant Tissues: The main functions of plant tissues encompass:
- Food Assimilation: Tissues like parenchyma are involved in photosynthesis and nutrient storage.
- Storage: Specialized tissues store starch, oils, and water.
- Mechanical Support: Sclerenchyma and collenchyma provide structural integrity and support to the plant.
Linking Assertion and Reason
- The reason elaborates on the functions of plant tissues, which directly relate to the types of tissues mentioned in the assertion.
- Meristematic tissues contribute to growth, while permanent tissues fulfill specific roles such as support and storage, thereby justifying the assertion.
Conclusion
Thus, both the assertion and reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is option 'A'. Understanding this relationship helps in grasping the fundamental concepts of plant biology, crucial for NEET preparation.
Plant tissues are essential components of plants, classified into two main types: meristematic and permanent. Each type plays a vital role in the overall functioning of the plant.
Assertion (A) Explained
- Meristematic Tissues: These are undifferentiated cells that can divide and contribute to growth. They are found in regions of the plant that are actively growing, like tips of roots and stems.
- Permanent Tissues: These tissues are differentiated and have specific functions. They include parenchyma, collenchyma, and sclerenchyma, each serving unique roles.
Reason (R) Explained
- Functions of Plant Tissues: The main functions of plant tissues encompass:
- Food Assimilation: Tissues like parenchyma are involved in photosynthesis and nutrient storage.
- Storage: Specialized tissues store starch, oils, and water.
- Mechanical Support: Sclerenchyma and collenchyma provide structural integrity and support to the plant.
Linking Assertion and Reason
- The reason elaborates on the functions of plant tissues, which directly relate to the types of tissues mentioned in the assertion.
- Meristematic tissues contribute to growth, while permanent tissues fulfill specific roles such as support and storage, thereby justifying the assertion.
Conclusion
Thus, both the assertion and reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is option 'A'. Understanding this relationship helps in grasping the fundamental concepts of plant biology, crucial for NEET preparation.
Light reaction otherwise called as- a)Photochemical phase
- b)Carboxylation
- c)Regeneration
- d)Biosynthetic phase
Correct answer is option 'A'. Can you explain this answer?
Light reaction otherwise called as
a)
Photochemical phase
b)
Carboxylation
c)
Regeneration
d)
Biosynthetic phase
|
|
Shraddha Pillai answered |
Photochemical phase or Light reaction
The light reaction is the first stage of photosynthesis that occurs in the thylakoid membrane of the chloroplast. It requires light energy to break down water molecules into oxygen and hydrogen ions. The hydrogen ions are used to generate ATP and NADPH, which are used in the second stage of photosynthesis, the dark reaction.
Process of Light Reaction:
1. Absorption of Light Energy: Chlorophyll pigments present in the thylakoid membrane absorb light energy and transfer it to the reaction center.
2. Generation of ATP: The absorbed light energy is used to generate ATP by the process of photophosphorylation.
3. Generation of NADPH: The absorbed light energy is also used to generate NADPH by the process of photoreduction.
4. Splitting of Water Molecules: Water molecules are split into oxygen and hydrogen ions by the process of photolysis.
5. Release of Oxygen: The oxygen produced by the photolysis of water is released into the atmosphere.
Importance of Light Reaction:
1. Production of ATP and NADPH: The light reaction produces ATP and NADPH, which are used in the dark reaction to synthesize glucose.
2. Release of Oxygen: The oxygen produced by the light reaction is released into the atmosphere, which is essential for the survival of living organisms.
3. Maintenance of Chloroplast: The light reaction helps in the maintenance of chloroplast by generating ATP, which is used to power various metabolic processes in the chloroplast.
Conclusion:
The light reaction is a critical process in photosynthesis that generates ATP and NADPH, which are used in the dark reaction to synthesize glucose. It also releases oxygen into the atmosphere, which is essential for life on earth.
The light reaction is the first stage of photosynthesis that occurs in the thylakoid membrane of the chloroplast. It requires light energy to break down water molecules into oxygen and hydrogen ions. The hydrogen ions are used to generate ATP and NADPH, which are used in the second stage of photosynthesis, the dark reaction.
Process of Light Reaction:
1. Absorption of Light Energy: Chlorophyll pigments present in the thylakoid membrane absorb light energy and transfer it to the reaction center.
2. Generation of ATP: The absorbed light energy is used to generate ATP by the process of photophosphorylation.
3. Generation of NADPH: The absorbed light energy is also used to generate NADPH by the process of photoreduction.
4. Splitting of Water Molecules: Water molecules are split into oxygen and hydrogen ions by the process of photolysis.
5. Release of Oxygen: The oxygen produced by the photolysis of water is released into the atmosphere.
Importance of Light Reaction:
1. Production of ATP and NADPH: The light reaction produces ATP and NADPH, which are used in the dark reaction to synthesize glucose.
2. Release of Oxygen: The oxygen produced by the light reaction is released into the atmosphere, which is essential for the survival of living organisms.
3. Maintenance of Chloroplast: The light reaction helps in the maintenance of chloroplast by generating ATP, which is used to power various metabolic processes in the chloroplast.
Conclusion:
The light reaction is a critical process in photosynthesis that generates ATP and NADPH, which are used in the dark reaction to synthesize glucose. It also releases oxygen into the atmosphere, which is essential for life on earth.
Calvin cycle is discovered by- a)Melvin Calvin
- b)Blackmann
- c)Cornelius van neil
- d)Hatch and Slack
Correct answer is option 'A'. Can you explain this answer?
Calvin cycle is discovered by
a)
Melvin Calvin
b)
Blackmann
c)
Cornelius van neil
d)
Hatch and Slack
|
|
Anjali Sharma answered |
The cycle was discovered in 1950 by Melvin Calvin, James Bassham, and Andrew Benson at the University of California, Berkeley by using the radioactive isotope carbon-14. Photosynthesis occurs in two stages in a cell.
The reaction which is responsible for the primary fixation of CO2 is catalysed by- a)PGA synthase
- b)RuBP carboxylase and PEP carboxylase
- c)RuBP carboxylase
- d)PEP carboxylase
Correct answer is option 'B'. Can you explain this answer?
The reaction which is responsible for the primary fixation of CO2 is catalysed by
a)
PGA synthase
b)
RuBP carboxylase and PEP carboxylase
c)
RuBP carboxylase
d)
PEP carboxylase
|
|
Megha Kulkarni answered |
Primary Fixation of CO2
The primary fixation of carbon dioxide (CO2) is the first step in the Calvin cycle, also known as the C3 cycle, which is the most common pathway of photosynthesis in plants. It involves the conversion of CO2 into an organic molecule that can be further processed to produce sugars.
RuBP Carboxylase and PEP Carboxylase
The primary fixation of CO2 is catalyzed by two enzymes: RuBP carboxylase (Ribulose-1,5-bisphosphate carboxylase/oxygenase, or Rubisco) and PEP carboxylase (Phosphoenolpyruvate carboxylase).
RuBP Carboxylase
- RuBP carboxylase is the enzyme responsible for the majority of CO2 fixation in plants.
- It catalyzes the carboxylation of Ribulose-1,5-bisphosphate (RuBP) with CO2 to form an unstable intermediate compound.
- RuBP carboxylase is highly specific to CO2 and plays a crucial role in the Calvin cycle, as it provides the starting point for the synthesis of organic molecules.
- This enzyme is present in the chloroplasts of plant cells and is considered one of the most abundant proteins on Earth.
PEP Carboxylase
- PEP carboxylase is an enzyme found in plants and some bacteria.
- It catalyzes the carboxylation of Phosphoenolpyruvate (PEP) with CO2 to form Oxaloacetate.
- PEP carboxylase has a higher affinity for CO2 compared to RuBP carboxylase and operates under conditions of low CO2 concentration or high oxygen concentration.
- It is an important enzyme in C4 plants, where it helps to minimize photorespiration and increase the efficiency of CO2 fixation.
Comparison
- While both RuBP carboxylase and PEP carboxylase are involved in the primary fixation of CO2, their roles differ.
- RuBP carboxylase is the main enzyme responsible for CO2 fixation in the Calvin cycle and is found in all photosynthetic organisms.
- PEP carboxylase, on the other hand, plays a significant role in C4 plants by enabling efficient CO2 fixation even under high oxygen or low CO2 conditions.
- Both enzymes contribute to the overall process of carbon fixation and are essential for the production of organic molecules in plants.
Therefore, option 'B' (RuBP carboxylase and PEP carboxylase) is the correct answer as both enzymes are involved in the primary fixation of CO2, with RuBP carboxylase being the main enzyme in most plants and PEP carboxylase playing a specific role in C4 plants.
The primary fixation of carbon dioxide (CO2) is the first step in the Calvin cycle, also known as the C3 cycle, which is the most common pathway of photosynthesis in plants. It involves the conversion of CO2 into an organic molecule that can be further processed to produce sugars.
RuBP Carboxylase and PEP Carboxylase
The primary fixation of CO2 is catalyzed by two enzymes: RuBP carboxylase (Ribulose-1,5-bisphosphate carboxylase/oxygenase, or Rubisco) and PEP carboxylase (Phosphoenolpyruvate carboxylase).
RuBP Carboxylase
- RuBP carboxylase is the enzyme responsible for the majority of CO2 fixation in plants.
- It catalyzes the carboxylation of Ribulose-1,5-bisphosphate (RuBP) with CO2 to form an unstable intermediate compound.
- RuBP carboxylase is highly specific to CO2 and plays a crucial role in the Calvin cycle, as it provides the starting point for the synthesis of organic molecules.
- This enzyme is present in the chloroplasts of plant cells and is considered one of the most abundant proteins on Earth.
PEP Carboxylase
- PEP carboxylase is an enzyme found in plants and some bacteria.
- It catalyzes the carboxylation of Phosphoenolpyruvate (PEP) with CO2 to form Oxaloacetate.
- PEP carboxylase has a higher affinity for CO2 compared to RuBP carboxylase and operates under conditions of low CO2 concentration or high oxygen concentration.
- It is an important enzyme in C4 plants, where it helps to minimize photorespiration and increase the efficiency of CO2 fixation.
Comparison
- While both RuBP carboxylase and PEP carboxylase are involved in the primary fixation of CO2, their roles differ.
- RuBP carboxylase is the main enzyme responsible for CO2 fixation in the Calvin cycle and is found in all photosynthetic organisms.
- PEP carboxylase, on the other hand, plays a significant role in C4 plants by enabling efficient CO2 fixation even under high oxygen or low CO2 conditions.
- Both enzymes contribute to the overall process of carbon fixation and are essential for the production of organic molecules in plants.
Therefore, option 'B' (RuBP carboxylase and PEP carboxylase) is the correct answer as both enzymes are involved in the primary fixation of CO2, with RuBP carboxylase being the main enzyme in most plants and PEP carboxylase playing a specific role in C4 plants.
In plant cells, synthesis of ATP by the chemiosmoticmechanism occurs during- a)Photosynthesis only.
- b)Respiration only.
- c)Both photosynthesis and respiration.
- d)Photorespiration only.
Correct answer is option 'C'. Can you explain this answer?
In plant cells, synthesis of ATP by the chemiosmoticmechanism occurs during
a)
Photosynthesis only.
b)
Respiration only.
c)
Both photosynthesis and respiration.
d)
Photorespiration only.
|
Ciel Knowledge answered |
The chemiosmotic hypothesis explains how cells produce energy. It describes how, similar to respiration, photosynthesis also uses this method.
The Calvin cycle proceeds in three stages:
1. Reduction, during which carbohydrate is formed at the expense of the photochemically made ATP and NADPH.
2. Regeneration, during which the carbon dioxide acceptor ribulose-1, 5-bisphosphate is formed.
3. Carboxylation, during which carbon dioxide combines with rubulose-1, 5-biphosphate.
Identify the correct sequence.- a)2-1-3
- b)1-2-3
- c)3-2-1
- d)3-1-2
- e)1-3-2
Correct answer is option 'D'. Can you explain this answer?
The Calvin cycle proceeds in three stages:
1. Reduction, during which carbohydrate is formed at the expense of the photochemically made ATP and NADPH.
2. Regeneration, during which the carbon dioxide acceptor ribulose-1, 5-bisphosphate is formed.
3. Carboxylation, during which carbon dioxide combines with rubulose-1, 5-biphosphate.
Identify the correct sequence.
1. Reduction, during which carbohydrate is formed at the expense of the photochemically made ATP and NADPH.
2. Regeneration, during which the carbon dioxide acceptor ribulose-1, 5-bisphosphate is formed.
3. Carboxylation, during which carbon dioxide combines with rubulose-1, 5-biphosphate.
Identify the correct sequence.
a)
2-1-3
b)
1-2-3
c)
3-2-1
d)
3-1-2
e)
1-3-2
|
|
Ayaan Madhukar answered |
Calvin cycle begins with fixation of CO2 into 3 C sugar by the process of carboxylation.
RUBISCO, present in the chloroplast stroma catalyzes carboxylation of ribulose -1, 5- biphosphate (RuBP) followed by immediate splitting of unstable product into 3-phosphoglyceric acid. Carboxylation is followed by a series of reduction reactions wherein 3 C compound 3-phosphoglyceric acid is reduced into 3 C compounds glyceraldehydes 3-phosphate (G3P); the reduction reactions are energized by ATP and NADPH serve as an electron donor. Three turns of Calvin cycle obtains 6 molecules of G3P, out of which one is used for glucose formation and rest are used in regeneration phase. The last phase of Calvin cycle, the regeneration phase ensures the continuous supply of RuBP for carboxylation and regenerates it using G3P.
Thus , the correct answer is 3-1-2...that is option (D)...
$$Hope it's help... $$
RUBISCO, present in the chloroplast stroma catalyzes carboxylation of ribulose -1, 5- biphosphate (RuBP) followed by immediate splitting of unstable product into 3-phosphoglyceric acid. Carboxylation is followed by a series of reduction reactions wherein 3 C compound 3-phosphoglyceric acid is reduced into 3 C compounds glyceraldehydes 3-phosphate (G3P); the reduction reactions are energized by ATP and NADPH serve as an electron donor. Three turns of Calvin cycle obtains 6 molecules of G3P, out of which one is used for glucose formation and rest are used in regeneration phase. The last phase of Calvin cycle, the regeneration phase ensures the continuous supply of RuBP for carboxylation and regenerates it using G3P.
Thus , the correct answer is 3-1-2...that is option (D)...
$$Hope it's help... $$
The excitation of electrons,finally down-hill to NADP+ causing it tobe reduced to NADPH+2 is- a)Redox potential
- b)ATP
- c)Z scheme
- d)Cytochromes
Correct answer is option 'C'. Can you explain this answer?
The excitation of electrons,finally down-hill to NADP+ causing it tobe reduced to NADPH+2 is
a)
Redox potential
b)
ATP
c)
Z scheme
d)
Cytochromes
|
Rhea Sarkar answered |
Excitation of electrons, transfer to another accepter, and finally down-hill to NADP+ causing it to be reduced to NADPH+ H+ is called the Z scheme.
Blackman's law is related to - a)respiration
- b)transpiration
- c)root pressure
- d)photosynthesis.
Correct answer is option 'D'. Can you explain this answer?
Blackman's law is related to
a)
respiration
b)
transpiration
c)
root pressure
d)
photosynthesis.
|
|
Stepway Academy answered |
Blackman formulated the principle of limiting factors. He studied the effect of CO2 concentration, light intensity and temperature on the rate of photosynthesis.
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