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All questions of Photosynthesis and Productivity for Year 11 Exam
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.
| | Anshika Shah answered |
Photosynthesis is a process by which green plants and some other organisms convert light energy into chemical energy stored in the bonds of glucose or other organic compounds. Photosynthesis occurs in two stages: the light-dependent reactions and the light-independent reactions. The light-dependent reactions occur in the thylakoid membranes of chloroplasts and produce ATP and NADPH, which are used in the light-independent reactions. The light-independent reactions occur in the stroma of the chloroplasts and use the ATP and NADPH produced in the light-dependent reactions to fix carbon dioxide into glucose.
The light-independent reactions are also known as the Calvin cycle or the dark reactions because they do not require light energy to occur. The dark reactions can occur at any time, day or night, as long as the necessary enzymes and substrates are present.
Why is the dark reaction in photosynthesis called so?
The dark reaction in photosynthesis is called so because it does not depend on light energy. The term "dark" in this context does not mean that the reactions only occur in the dark. Instead, it refers to the fact that the reactions can occur in the absence of light. The dark reactions can occur during the day or night, as long as the necessary enzymes and substrates are present. The dark reactions use the ATP and NADPH produced in the light-dependent reactions to fix carbon dioxide into glucose.
Conclusion
The dark reaction in photosynthesis is an important process that occurs in the stroma of chloroplasts in green plants and some other organisms. The term "dark" in this context refers to the fact that the reactions do not require light energy to occur, and can occur at any time, day or night, as long as the necessary enzymes and substrates are present.
The light-independent reactions are also known as the Calvin cycle or the dark reactions because they do not require light energy to occur. The dark reactions can occur at any time, day or night, as long as the necessary enzymes and substrates are present.
Why is the dark reaction in photosynthesis called so?
The dark reaction in photosynthesis is called so because it does not depend on light energy. The term "dark" in this context does not mean that the reactions only occur in the dark. Instead, it refers to the fact that the reactions can occur in the absence of light. The dark reactions can occur during the day or night, as long as the necessary enzymes and substrates are present. The dark reactions use the ATP and NADPH produced in the light-dependent reactions to fix carbon dioxide into glucose.
Conclusion
The dark reaction in photosynthesis is an important process that occurs in the stroma of chloroplasts in green plants and some other organisms. The term "dark" in this context refers to the fact that the reactions do not require light energy to occur, and can occur at any time, day or night, as long as the necessary enzymes and substrates are present.
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.
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.
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.
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)...
$$Hope it's help... $$
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 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.
What is the role of the light-harvesting complexes (LHC) in the light reactions of photosynthesis?- a)They absorb only one wavelength of light.
- b)They are responsible for splitting water and releasing oxygen.
- c)They help to make photosynthesis more efficient by absorbing different wavelengths of light.
- d)They form the reaction center for photosystem I and II.
Correct answer is option 'C'. Can you explain this answer?
a)
They absorb only one wavelength of light.
b)
They are responsible for splitting water and releasing oxygen.
c)
They help to make photosynthesis more efficient by absorbing different wavelengths of light.
d)
They form the reaction center for photosystem I and II.
| | Moumita Datta answered |
Role of Light-Harvesting Complexes (LHC) in Photosynthesis
Light-harvesting complexes (LHC) play a crucial role in the light reactions of photosynthesis, primarily by enhancing the efficiency of light absorption. Here's a detailed explanation of their function:
Absorption of Light
- LHCs contain pigments, such as chlorophyll a, chlorophyll b, and carotenoids.
- These pigments can absorb light at various wavelengths, allowing the plant to capture a broader spectrum of sunlight.
- This diverse absorption helps maximize energy capture, which is essential for photosynthesis.
Energy Transfer
- Once light is absorbed, the energy is transferred from the LHCs to the reaction centers of photosystem I and II.
- This energy transfer process is highly efficient, ensuring that most of the absorbed light energy is used for the subsequent chemical reactions.
Efficiency of Photosynthesis
- By capturing multiple wavelengths of light, LHCs significantly increase the overall efficiency of the photosynthetic process.
- This adaptability allows plants to thrive in various light conditions, optimizing energy production even in low-light environments.
Conclusion
- In summary, light-harvesting complexes are vital for photosynthesis as they absorb different wavelengths of light and transfer the energy to reaction centers, enhancing the overall efficiency of the light reactions.
- Therefore, the correct answer is option 'C': They help to make photosynthesis more efficient by absorbing different wavelengths of light.
Light-harvesting complexes (LHC) play a crucial role in the light reactions of photosynthesis, primarily by enhancing the efficiency of light absorption. Here's a detailed explanation of their function:
Absorption of Light
- LHCs contain pigments, such as chlorophyll a, chlorophyll b, and carotenoids.
- These pigments can absorb light at various wavelengths, allowing the plant to capture a broader spectrum of sunlight.
- This diverse absorption helps maximize energy capture, which is essential for photosynthesis.
Energy Transfer
- Once light is absorbed, the energy is transferred from the LHCs to the reaction centers of photosystem I and II.
- This energy transfer process is highly efficient, ensuring that most of the absorbed light energy is used for the subsequent chemical reactions.
Efficiency of Photosynthesis
- By capturing multiple wavelengths of light, LHCs significantly increase the overall efficiency of the photosynthetic process.
- This adaptability allows plants to thrive in various light conditions, optimizing energy production even in low-light environments.
Conclusion
- In summary, light-harvesting complexes are vital for photosynthesis as they absorb different wavelengths of light and transfer the energy to reaction centers, enhancing the overall efficiency of the light reactions.
- Therefore, the correct answer is option 'C': They help to make photosynthesis more efficient by absorbing different wavelengths of light.
How many turns does the Calvin cycle take for the generation of one molecule of glucose?- a)6
- b)4
- c)2
- d)8
Correct answer is option 'A'. Can you explain this answer?
How many turns does the Calvin cycle take for the generation of one molecule of glucose?
a)
6
b)
4
c)
2
d)
8
| | Ayaan Madhukar answered |
Six turn
Because the carbohydrate molecule has 6 carbon atom , it takes 6 turns of calvin cycle to make one carbohydrate molecule.
So, correct answer is "6"...
$$Hope it's help... $$
Because the carbohydrate molecule has 6 carbon atom , it takes 6 turns of calvin cycle to make one carbohydrate molecule.
So, correct answer is "6"...
$$Hope it's help... $$
Which of the following statements correctly describes the reaction center in Photosystem I (PS I) and Photosystem II (PS II)?- a)Both PS I and PS II have the same absorption peak for their reaction center chlorophyll a molecules.
- b)The reaction center in PS I has an absorption peak at 680 nm, while PS II has an absorption peak at 700 nm.
- c)The reaction center in PS I is called P700, and in PS II it is called P680.
- d)The reaction centers in PS I and PS II both use chlorophyll b for absorption.
Correct answer is option 'C'. Can you explain this answer?
a)
Both PS I and PS II have the same absorption peak for their reaction center chlorophyll a molecules.
b)
The reaction center in PS I has an absorption peak at 680 nm, while PS II has an absorption peak at 700 nm.
c)
The reaction center in PS I is called P700, and in PS II it is called P680.
d)
The reaction centers in PS I and PS II both use chlorophyll b for absorption.
 | Infinity Academy answered |
In Photosystem I, the reaction center chlorophyll a has an absorption peak at 700 nm, called P700, and in Photosystem II, the reaction center chlorophyll a has an absorption peak at 680 nm, called P680. This distinction is crucial for the functioning of the light reactions in photosynthesis.
Topic in NCERT: Photosynthesis in higher plants
Line in NCERT: "in ps i the reaction centre chlorophyll a has an absorption peak at 700 nm, hence is called p700, while in ps ii it has absorption maxima at 680 nm, and is called p680."
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