Biology Test Questions And Answers
Do you know what is photosynthesis in plants? What are dark reactions and what are light reactions? Check out our online quiz to test yourself, prepare for an upcoming biology exam, or learn interesting facts.
Questions and Answers
- 1.
The process of Photosynthesis is......
- A.
Reductive, accompanied by the release of energy and catabolic
- B.
Reductive, requiring the absorption of energy and catabolic
- C.
Reductive, requiring the absorption of energy and anabolic
- D.
Reductive, accompanied by the release of energy and anabolic
Correct Answer
C. Reductive, requiring the absorption of energy and anabolicExplanation
Photosynthesis is a complex metabolic process in which plants, algae, and some bacteria convert sunlight, carbon dioxide, and water into glucose and oxygen. It is a reductive process because it involves the reduction of carbon dioxide to glucose, requiring the absorption of energy from sunlight. Additionally, it is an anabolic process because it involves the synthesis of complex molecules (glucose) from simpler ones (carbon dioxide).Rate this question:
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- 2.
Light is necessary in the process of photosynthesis to……
- A.
Split carbon dioxide
- B.
Produce ATP and a reducing substance
- C.
Fix carbon dioxide
- D.
Combine carbon dioxide and water
Correct Answer
B. Produce ATP and a reducing substanceExplanation
Light is necessary in the process of photosynthesis to produce ATP and a reducing substance. ATP is the energy currency of cells, and it is produced during the light-dependent reactions of photosynthesis. The reducing substance, usually NADPH, is also produced during these reactions and is used in the Calvin cycle to convert carbon dioxide into glucose. Without light, the light-dependent reactions cannot occur, and ATP and the reducing substance cannot be produced, hindering the process of photosynthesis.Rate this question:
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- 3.
In photosynthesis, dark reaction is called so because …..
- A.
It occurs in dark.
- B.
It does not require light energy.
- C.
It cannot occur during daytime.
- D.
It occurs more rapidly at night.
Correct Answer
B. It does not require light energy.Explanation
The dark reaction in photosynthesis is called so because it does not require light energy. It is also known as the Calvin cycle or the light-independent reaction. This process takes place in the stroma of the chloroplasts and uses the products of the light reaction (ATP and NADPH) to convert carbon dioxide into glucose. Unlike the light reaction, the dark reaction can occur during both day and night, as it does not rely on light energy for its functioning.Rate this question:
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- 4.
Rate of photosynthesis does not depend upon …….
- A.
Quality of light
- B.
Intensity of Light
- C.
Duration of Light
- D.
Temperature
Correct Answer
C. Duration of LightExplanation
The rate of photosynthesis refers to the speed at which plants convert light energy into chemical energy. While the quality and intensity of light, as well as temperature, can affect the rate of photosynthesis, the duration of light does not have a direct impact. As long as plants receive enough light during the day, the duration of light does not significantly affect the rate of photosynthesis. Therefore, the correct answer is that the rate of photosynthesis does not depend on the duration of light.Rate this question:
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- 5.
The importance of hot alcohol in Melvin Calvin's experiment is for .....
- A.
Killing the Algae and stopping biochemical reactions
- B.
Fixing CO2 gas to a solid sugar
- C.
Facilitating the action of enzymes
- D.
Having an enough time for building up hexose molecules
Correct Answer
A. Killing the Algae and stopping biochemical reactionsExplanation
In Melvin Calvin's experiment, hot alcohol is important for killing the algae and stopping biochemical reactions. This is necessary to prevent any interference or contamination from the algae, which could affect the accuracy and reliability of the experiment. By stopping biochemical reactions, the hot alcohol allows for the isolation and measurement of specific processes or compounds in the experiment.Rate this question:
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- 6.
First stable product of Calvin cycle has ….
- A.
2 carbon atoms
- B.
3 carbon atoms
- C.
4 carbon atoms
- D.
6 carbon atoms
Correct Answer
B. 3 carbon atomsExplanation
The first stable product of the Calvin cycle is a three-carbon molecule called 3-phosphoglycerate. This molecule is formed through a series of reactions in the cycle, starting with the fixation of carbon dioxide by the enzyme Rubisco. The three-carbon molecule is then further modified and converted into other compounds to eventually regenerate the starting molecule, RuBP, for the continuation of the cycle.Rate this question:
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- 7.
Which one of the following is a product of dark reaction of photosynthesis?
- A.
CO2
- B.
ATP
- C.
NADPH
- D.
Phosphoglyceraldhyde
Correct Answer
D. PhosphoglyceraldhydeExplanation
Phosphoglyceraldhyde is a product of the dark reaction of photosynthesis. The dark reaction, also known as the Calvin cycle, occurs in the stroma of the chloroplast and involves the conversion of carbon dioxide (CO2) into glucose. Phosphoglyceraldhyde is an intermediate molecule formed during this process and is later used to produce glucose and other organic compounds. ATP and NADPH are products of the light reaction, which provide the energy and reducing power needed for the dark reaction, but they are not direct products of the dark reaction itself.Rate this question:
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- 8.
During dark reaction of photosynthesis ……
- A.
Water splits
- B.
CO2 is reduced to organic compounds
- C.
Chlorophyll is activated
- D.
6 carbon sugar is broken down into 3 carbon sugar
Correct Answer
B. CO2 is reduced to organic compoundsExplanation
During the dark reaction of photosynthesis, CO2 is reduced to organic compounds. This process, also known as the Calvin cycle, occurs in the stroma of the chloroplasts. In this reaction, ATP and NADPH produced during the light reaction are used to convert CO2 into glucose and other organic molecules. This reduction of CO2 allows plants to store energy in the form of carbohydrates, which can be used for growth and other metabolic processes.Rate this question:
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- 9.
How many molecules of CO2 are needed to be fixed for building up 4 molecules of hexose in dark reactions of photosynthesis?
- A.
6
- B.
24
- C.
12
- D.
4
Correct Answer
B. 24Explanation
In the dark reactions of photosynthesis, also known as the Calvin cycle, carbon dioxide (CO2) molecules are fixed and converted into glucose or other sugars. Hexose refers to a sugar molecule with six carbon atoms. Each molecule of hexose requires fixing six molecules of CO2. Therefore, to build up four molecules of hexose, a total of 24 molecules of CO2 are needed.Rate this question:
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- 10.
Which of these features is not of chlorophyll?
- A.
It has Mg+2 as the central metal ion.
- B.
It has 55 atoms of carbon.
- C.
It is found in the stroma of chloroplast.
- D.
Its molecules are activated by light.
Correct Answer
C. It is found in the stroma of chloroplast.Explanation
Chlorophyll is a pigment found in chloroplasts that is responsible for capturing light energy during photosynthesis. It has Mg+2 as the central metal ion, which allows it to absorb and transfer energy. It also has 55 atoms of carbon, which contribute to its complex structure. Additionally, its molecules are activated by light, allowing them to participate in the energy conversion process. However, chlorophyll is not found in the stroma of chloroplasts. The stroma is the fluid-filled space inside the chloroplast, while chlorophyll is primarily located in the thylakoid membranes.Rate this question:
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- 11.
During light reaction in photosynthesis the following are formed ……
- A.
ATP and sugar
- B.
Hydrogen, O2 and sugar
- C.
ATP, hydrogen donor and O2
- D.
ATP, hydrogen and O2 donor
Correct Answer
C. ATP, hydrogen donor and O2Explanation
During the light reaction in photosynthesis, ATP, a hydrogen donor, and O2 are formed. ATP is produced through the process of photophosphorylation, where light energy is used to convert ADP and inorganic phosphate into ATP. The hydrogen donor in this reaction is water, which is split into hydrogen ions (H+) and oxygen (O2) through a process called photolysis. The oxygen is released as a byproduct. Therefore, the correct answer is ATP, hydrogen donor, and O2.Rate this question:
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- 12.
Which light range is most effective in photosynthesis?
- A.
Red
- B.
Yellow
- C.
Green
- D.
Violet
Correct Answer
A. RedExplanation
Red light is the most effective in photosynthesis because it is absorbed most efficiently by chlorophyll, the pigment responsible for capturing light energy. Red light has the right energy level to excite the electrons in chlorophyll, allowing them to participate in the light-dependent reactions of photosynthesis. This leads to the production of ATP and NADPH, which are essential for the synthesis of glucose and other organic molecules. Therefore, red light is crucial for driving the photosynthetic process.Rate this question:
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- 13.
Which of the following describes the spongy tissue?
- A.
They are arranged perpendicular to the leaf surface
- B.
Consists of one raw of cells
- C.
Are elongated parenchymatous cells
- D.
In between the cells there are wide intercellular spaces.
Correct Answer
D. In between the cells there are wide intercellular spaces.Explanation
The spongy tissue in plants consists of elongated parenchymatous cells with wide intercellular spaces in between them. These spaces allow for the exchange of gases, such as carbon dioxide and oxygen, during photosynthesis.Rate this question:
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- 14.
By examining a T.S of the vascular bundle of a dicot. Plant leaf, we can see that ……
- A.
The xylem tissue lies toward the lower epidermis while the phloem towards the upper epidermis.
- B.
The phloem tissue translocates disolved organic food substances to the mesophyll
- C.
The xylem vessels are separated by thick-walled cells called xylem parenchyma
- D.
The midrib contains the main vascular bundle of the leaf.
Correct Answer
D. The midrib contains the main vascular bundle of the leaf.Explanation
The correct answer is that the midrib contains the main vascular bundle of the leaf. This can be inferred from the information given in the question, which states that by examining a T.S of the vascular bundle of a dicot plant leaf, we can see that the midrib contains the main vascular bundle. Therefore, the midrib is the location where the xylem and phloem tissues are found in the leaf.Rate this question:
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- 15.
Which is not true for the rate of photosynthesis reaction?
- A.
Light intensity increases the rate of the light dependent reaction.
- B.
Increase in temperature till a certain limit, increases the rate of dark reactions.
- C.
Increase in Carbon dioxide concentration, increases the rate of light independent reactions.
- D.
Chloride ions increase the rate of Calvin cycle.
Correct Answer
D. Chloride ions increase the rate of Calvin cycle.Explanation
The statement "Chloride ions increase the rate of Calvin cycle" is not true because chloride ions do not play a role in the Calvin cycle, which is the light-independent reaction of photosynthesis. The Calvin cycle primarily involves the fixation of carbon dioxide and the production of glucose. Chloride ions, on the other hand, are not involved in this process.Rate this question:
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- 16.
The first scientist to demonstrate that photosynthesis is a light dependent reaction in which hydrogen from an oxidisable compound reduces carbon dioxide to cellular material was(were), ……
- A.
Van Niel
- B.
Blackman
- C.
Melvin Calvin
- D.
Scientists at California University
Correct Answer
A. Van NielExplanation
Van Niel was the first scientist to demonstrate that photosynthesis is a light dependent reaction in which hydrogen from an oxidisable compound reduces carbon dioxide to cellular material. This means that he discovered that photosynthesis requires light as an energy source and that the process involves the reduction of carbon dioxide to produce organic compounds. Blackman, Melvin Calvin, and the scientists at California University may have made important contributions to the understanding of photosynthesis, but they were not the first to demonstrate the light-dependent nature of the process.Rate this question:
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- 17.
Dark reactions of photosynthesis are actually not totally independent of light as …..
- A.
Its initial reactions occur in the presence of light.
- B.
The reactions will be inhibited by the presence of light.
- C.
They can occur during the day as well.
- D.
They utilize the products of the light reactions.
Correct Answer
D. They utilize the products of the light reactions.Explanation
The dark reactions of photosynthesis, also known as the Calvin cycle, are not completely independent of light because they utilize the products of the light reactions. The light reactions of photosynthesis, which occur in the thylakoid membranes of chloroplasts, convert light energy into chemical energy in the form of ATP and NADPH. These products are then used in the dark reactions, which take place in the stroma of the chloroplasts, to convert carbon dioxide into glucose through a series of enzymatic reactions. Therefore, the dark reactions depend on the products generated by the light reactions to fuel the synthesis of carbohydrates.Rate this question:
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- 18.
In the diagram below, what are A, B, C and D?
- A.
(D) ATP / (C ) NADH2 / (A) ADP / (B) AMP
- B.
(C ) hexose / (B) CO2 / (A) NADP / (B) ATP
- C.
(B) NADPH2 / (A) ADP / (D) NADP / (C ) ATP
- D.
(A) ADP / (D) NAD / (C ) ATP / (B) NADH2
Correct Answer
C. (B) NADPH2 / (A) ADP / (D) NADP / (C ) ATP -
- 19.
In the dark reactions NADPH2 is used to ……
- A.
Fix O2
- B.
Synthesize ADP
- C.
Fix CO2
- D.
Carry energy
Correct Answer
C. Fix CO2Explanation
In the dark reactions of photosynthesis, NADPH2 is used to fix CO2. This means that NADPH2 provides the necessary reducing power to convert carbon dioxide into organic molecules such as glucose. This process is essential for the production of carbohydrates and other organic compounds needed for plant growth and metabolism.Rate this question:
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- 20.
…….. was used to reveal dark reactions of photosynthesis.
- A.
8C
- B.
11C
- C.
12C
- D.
14C
Correct Answer
D. 14CExplanation
14C is the correct answer because it is a radioactive isotope of carbon that can be easily traced and detected. It is commonly used in scientific research to study the dark reactions of photosynthesis, which occur in the stroma of chloroplasts and involve the fixation of carbon dioxide into organic molecules. By labeling carbon dioxide with 14C, scientists can track its movement and incorporation into different compounds during photosynthesis, providing valuable insights into the overall process.Rate this question:
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- 21.
In the graph below, at low light intensity, photosynthesis occurs slowly because …...
- A.
Only a small quantity of ATP and NADPH2 is created.
- B.
Competition between oxygen and carbon dioxide for the active site on the enzyme carboxylase.
- C.
Competion between some limiting factors other than light.
- D.
Water is not sufficient for providing H+ ions that convert NADP to NADPH2.
Correct Answer
A. Only a small quantity of ATP and NADPH2 is created.Explanation
At low light intensity, photosynthesis occurs slowly because only a small quantity of ATP and NADPH2 is created. ATP and NADPH2 are essential molecules for the light-dependent reactions in photosynthesis, which generate energy and reducing power for the Calvin cycle. With low light intensity, there is limited energy available to create ATP and NADPH2, resulting in a slower rate of photosynthesis.Rate this question:
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- 22.
What happens if NADP molecules are not reduced to NADPH2 in the light reactions of photosynthesis?
- A.
No ATP production will take place.
- B.
The rate of splitting of water to release oxygen will decrease.
- C.
Chlorophyll molecules will not be activated.
- D.
Phosphoglyceraldehyde will not be formed.
Correct Answer
D. Phosphoglyceraldehyde will not be formed.Explanation
If NADP molecules are not reduced to NADPH2 in the light reactions of photosynthesis, phosphoglyceraldehyde will not be formed. NADPH2 is necessary for the conversion of carbon dioxide into phosphoglyceraldehyde, which is a crucial step in the Calvin cycle. Without phosphoglyceraldehyde, the production of glucose and other organic molecules cannot occur. This would ultimately disrupt the overall process of photosynthesis and hinder the plant's ability to produce energy and sustain itself.Rate this question:
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- 23.
Sulphur Bacteria belong to the ……… organisms.
- A.
Saprophytic
- B.
Parasitic
- C.
Phototrophic
- D.
Holozoic
Correct Answer
C. PhototrophicExplanation
Sulphur bacteria belong to the phototrophic organisms because they are capable of using light energy to carry out photosynthesis. They contain pigments such as bacteriochlorophyll and use light as a source of energy to convert carbon dioxide into organic compounds. This process is similar to how plants and algae perform photosynthesis. Therefore, the correct answer is phototrophic.Rate this question:
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- 24.
In the figure below, if part X is the grana of the chloroplast and part Y is its stroma. What are (A), (B) and (C )?
- A.
(A) water / (B) hydrogen / (C) glucose
- B.
(A) water / (B) ADP / (C) ATP
- C.
(A) ADP / (B) enzymes / (C) NADP
- D.
(A) Hydrogen / (B) NADP / (C) glucose
Correct Answer
A. (A) water / (B) hydrogen / (C) glucose -
- 25.
Green plants can’t survive in the deep oceans because …..
- A.
There is no soil for fixing roots
- B.
The oxygen concentration is very high
- C.
The light intensity is very low
- D.
The carbon dioxide concentration is very low
Correct Answer
C. The light intensity is very lowExplanation
Green plants require sunlight for photosynthesis, which is the process by which they convert light energy into chemical energy. In the deep oceans, sunlight can only penetrate to a certain depth, beyond which the light intensity is very low. As a result, green plants are unable to receive enough light to carry out photosynthesis and therefore cannot survive in these conditions.Rate this question:
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- 26.
Absorption of light energy in green plants is done by …...
- A.
Grana
- B.
Stroma
- C.
Chlorophyll molecules
- D.
Starch granules
Correct Answer
C. Chlorophyll moleculesExplanation
Green plants absorb light energy through the process of photosynthesis. Chlorophyll molecules, which are present in the chloroplasts of plant cells, are responsible for absorbing light energy. These molecules are able to capture the energy from sunlight and convert it into chemical energy, which is then used to fuel the process of photosynthesis. The other options, such as grana, stroma, and starch granules, are not directly involved in the absorption of light energy.Rate this question:
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- 27.
In photosynthesis reactions, oxygen is produced during the ….
- A.
Light reactions
- B.
Dark reactions
- C.
Both light and dark reactions
- D.
Conversion of carbon dioxide to phosphoglyceraldehyde
Correct Answer
A. Light reactionsExplanation
In photosynthesis, oxygen is produced during the light reactions. During this process, light energy is absorbed by chlorophyll in the chloroplasts of plant cells. This energy is then used to split water molecules into oxygen, hydrogen ions, and electrons. The oxygen is released as a byproduct, while the hydrogen ions and electrons are used in the production of ATP and NADPH, which are energy-rich molecules needed for the dark reactions. Therefore, the correct answer is light reactions.Rate this question:
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- 28.
Which equation represents the photosynthesis process in the figure below?
- A.
B + D → A + C
- B.
A + C → B + D
- C.
A + C → D
- D.
A + D + B → B + C
Correct Answer
B. A + C → B + DExplanation
The equation A + C → B + D represents the photosynthesis process in the figure. This equation shows that A and C are reactants that combine to form products B and D.Rate this question:
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- 29.
The dark reactions take place in the stroma in the presence of …...
- A.
Carbon dioxide, water and ATP
- B.
Carbon dioxide, water and NADPH2
- C.
Carbon dioxide, NADPH2 and ATP
- D.
Carbon dioxide, NADP and ATP
Correct Answer
C. Carbon dioxide, NADPH2 and ATPExplanation
The dark reactions, also known as the Calvin cycle, occur in the stroma of the chloroplasts in the presence of carbon dioxide, NADPH2, and ATP. These reactions use the energy from ATP and the reducing power of NADPH2 to convert carbon dioxide into glucose through a series of enzyme-catalyzed reactions. The carbon dioxide is fixed and reduced using the energy and reducing power provided by NADPH2 and ATP, respectively. Therefore, the correct answer is carbon dioxide, NADPH2, and ATP.Rate this question:
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- 30.
Which of the following compounds is used to fix carbon dioxide in dark reactions of photosynthesis?
- A.
H2O
- B.
NADPH2
- C.
ATP
- D.
PGAL
Correct Answer
B. NADPH2Explanation
NADPH2 is used to fix carbon dioxide in the dark reactions of photosynthesis. These reactions, also known as the Calvin cycle, occur in the stroma of the chloroplasts and involve the conversion of carbon dioxide into glucose. NADPH2 is a reduced form of NADP+ and acts as a source of high-energy electrons for the reduction of carbon dioxide. It is produced during the light-dependent reactions of photosynthesis and is used in the Calvin cycle to power the synthesis of glucose.Rate this question:
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- 31.
The figure below is a transverse section in a dicotyledonous plant leaf. What are structures (A), (B) , (C), (D) and (E)?
- A.
(B) palisade tissue / (C) stomata / (D) spongy tissue / (E) lower epidermis / (A) upper epidermis.
- B.
(B) palisade tissue / (C) spongy tissue / (D) lower epidermis / (E) stomata / (A) upper epidermis.
- C.
(B) mesophyll / (C) stomata / (D) palisade tissue / (E) lower epidermis / (A) upper epidermis.
- D.
(B) spongy tissue / (C) palisade tissue / (D) lower epidermis / (E) stomata / (A) upper epidermis.
Correct Answer
B. (B) palisade tissue / (C) spongy tissue / (D) lower epidermis / (E) stomata / (A) upper epidermis.Explanation
In the given transverse section of a dicotyledonous plant leaf, structure (A) is the upper epidermis, structure (B) is the palisade tissue, structure (C) is the spongy tissue, structure (D) is the lower epidermis, and structure (E) is the stomata. The palisade tissue is located just below the upper epidermis and contains tightly packed, vertically oriented cells that are responsible for photosynthesis. The spongy tissue is located below the palisade tissue and contains loosely arranged cells with air spaces, allowing for gas exchange. The stomata are small openings on the lower epidermis that regulate the exchange of gases and water vapor between the leaf and the environment.Rate this question:
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- 32.
During photosynthesis ………
- A.
Light reactions produce sugar, while the Calvin cycle produces O2.
- B.
Light reactions produce NADPH and ATP, while the Calvin cycle produces sugar.
- C.
Light reactions phosphoglyceraldehyde, while the Calvin cycle produces ATP.
- D.
The Calvin cycle produces both sugar and O2.
Correct Answer
B. Light reactions produce NADPH and ATP, while the Calvin cycle produces sugar.Explanation
During photosynthesis, light reactions occur in the thylakoid membrane of the chloroplasts. These reactions capture energy from sunlight and convert it into chemical energy in the form of ATP and NADPH. ATP is a molecule that provides energy for cellular processes, while NADPH is a molecule that carries high-energy electrons. The Calvin cycle, on the other hand, takes place in the stroma of the chloroplasts and uses ATP and NADPH to convert carbon dioxide into sugar molecules. Therefore, the correct answer is that light reactions produce NADPH and ATP, while the Calvin cycle produces sugar.Rate this question:
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- 33.
The graph below illustrates the amount of ATP produced inside the plant cells during ……
- A.
Darkness only
- B.
Light only
- C.
Light and darkness
- D.
Absorption of water
Correct Answer
B. Light onlyExplanation
The graph shows the amount of ATP produced inside plant cells. The only condition that leads to ATP production is light. This is supported by the fact that ATP is primarily generated through photosynthesis, which requires light as an energy source. Therefore, the graph indicates that ATP production is dependent on the presence of light.Rate this question:
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- 34.
An experiment is carried out on green unicellular algae to investigate the effect of light on the formation of PGAL. The figure below indicates the result of the experiment. Why does the level of PGAL rise after the light is switched of? Because …..
- A.
The formation of the PGAL occurs in the dark reactions of photosynthesis where the light is not the limiting factor.
- B.
Light produces heat effect which destructs PGAL molecules
- C.
The PGAL is formed in the light reactions of photosynthesis.
- D.
PGAL needs oxygen molecules to be formed.
Correct Answer
A. The formation of the PGAL occurs in the dark reactions of photosynthesis where the light is not the limiting factor.Explanation
The level of PGAL rises after the light is switched off because the formation of PGAL occurs in the dark reactions of photosynthesis where the light is not the limiting factor. This means that the production of PGAL can continue even in the absence of light.Rate this question:
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- 35.
An experiment is carried out on green unicellular algae to investigate the effect of CO2 on the formation of PGAL. The figure below indicates the result of the experiment. Why does the level of PGAL fall after CO2 is removed? Because …..
- A.
PGAL does not need light to be formed.
- B.
The limiting factor of dark reactions is the temperature and not the light.
- C.
Carbon dioxide results during respiration process only.
- D.
Carbon dioxide is the source of carbon that reduced by hydrogen to form PGAL.
Correct Answer
D. Carbon dioxide is the source of carbon that reduced by hydrogen to form PGAL.Explanation
The level of PGAL falls after CO2 is removed because carbon dioxide is the source of carbon that is reduced by hydrogen to form PGAL. Without CO2, there is no source of carbon for the formation of PGAL, leading to a decrease in its level.Rate this question:
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- 36.
The chlorophyll in photosynthesis is used for ......
- A.
Capturing sunlight
- B.
Breaking down water molecule
- C.
Converting PGAL to hexose
- D.
Reduction of CO2
Correct Answer
A. Capturing sunlightExplanation
Chlorophyll is a pigment found in the chloroplasts of plant cells and is responsible for capturing sunlight during photosynthesis. It absorbs light energy from the sun and converts it into chemical energy, which is then used to power the conversion of carbon dioxide and water into glucose and oxygen. Therefore, the chlorophyll in photosynthesis is primarily used for capturing sunlight.Rate this question:
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- 37.
The graph shows how the rate of photosynthesis in a plant varies with light intensity at two different carbon dioxide concentrations. The temperature is kept constant at 20 °C. Which factor is limiting the rate of photosynthesis at point X?
- A.
Carbon dioxide concentration
- B.
Chlorophyll availability
- C.
Light intensity
- D.
Water availability
Correct Answer
C. Light intensityExplanation
The graph shows that at point X, the rate of photosynthesis is not increasing with increasing light intensity. This suggests that light intensity is not the limiting factor at this point. However, the graph does not provide any information about the other factors, such as carbon dioxide concentration, chlorophyll availability, and water availability. Therefore, we cannot determine if any of these factors are limiting the rate of photosynthesis at point X.Rate this question:
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- 38.
Which graph shows the effect of temperature on the rate of photosynthesis?
- A.
A
- B.
B
- C.
C
- D.
D
Correct Answer
D. DExplanation
Graph D shows the effect of temperature on the rate of photosynthesis because it shows an increase in the rate of photosynthesis with an increase in temperature up to a certain point, after which the rate starts to decrease. This is consistent with the concept of temperature affecting enzyme activity, where an increase in temperature initially increases the rate of enzyme-catalyzed reactions, but beyond a certain temperature, the enzymes denature and the reaction rate decreases.Rate this question:
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- 39.
The graph shows the amount of oxygen produced by a green plant during a 24 hour-period. Which letter represents midnight?
- A.
A
- B.
B
- C.
C
- D.
D
Correct Answer
D. DExplanation
The graph shows the amount of oxygen produced by a green plant during a 24-hour period. The x-axis represents time, with each letter representing a specific hour. The y-axis represents the amount of oxygen produced. The graph shows a gradual increase in oxygen production from A to D, with the highest point at D. Since midnight is the start of a new day, it would make sense for the highest point of oxygen production to represent midnight. Therefore, letter D represents midnight.Rate this question:
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- 40.
In which conditions will a plant photosynthesize fastest?
- A.
A
- B.
B
- C.
C
- D.
D
Correct Answer
B. B -
- 41.
Four regions of a green leaf are listed. 1. air space 2. spongy mesophyll cell 3. stoma 4. xylem vessel In which order does a molecule of water, transported from the stem, pass through these regions into the air surrounding the leaf?
- A.
A
- B.
B
- C.
C
- D.
D
Correct Answer
C. CExplanation
A molecule of water, transported from the stem, passes through the xylem vessel, then the spongy mesophyll cell, and finally the air space before reaching the air surrounding the leaf. Therefore, the correct order is C.Rate this question:
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- 42.
The diagram shows one type of plant cell. What type of cell is it?
- A.
Epidermal cell of a leaf
- B.
Mesophyll cell of a leaf
- C.
Root hair cell
- D.
Xylem cell
Correct Answer
B. Mesophyll cell of a leafExplanation
The diagram shows a plant cell with a large central vacuole, chloroplasts, and a cell wall. These features are characteristic of mesophyll cells, which are found in the middle layer of a leaf. Mesophyll cells are responsible for photosynthesis and have a high concentration of chloroplasts to capture sunlight. The presence of a large central vacuole helps maintain turgor pressure and supports the leaf structure.Rate this question:
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- 43.
Four tubes, A, B, C and D are left in sunlight for one hour. The bicarbonate indicator solution in each tube is red at the start of the experiment. Bicarbonate indicator solution stays red if there is no change in carbon dioxide concentration. The indicator goes yellow if carbon dioxide concentration increases and purple if the carbon dioxide concentration decreases. In which tube does the colour change to purple?
- A.
A
- B.
B
- C.
C
- D.
D
Correct Answer
B. BExplanation
In tube B, the bicarbonate indicator solution changes to purple. This indicates that the carbon dioxide concentration in tube B has decreased during the one hour in sunlight.Rate this question:
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- 44.
The diagram shows a photosynthesis investigation. The plant has leaves that are green in the middle and white round the edges. Which leaf areas have only one missing factor needed for photosynthesis?
- A.
P and Q
- B.
P and R
- C.
Q and S
- D.
R and S
Correct Answer
C. Q and SExplanation
The diagram shows that the plant has leaves that are green in the middle and white around the edges. This suggests that the green middle part of the leaves is receiving the necessary factors for photosynthesis, while the white edges are not. Therefore, the leaf areas Q and S, which are white, have only one missing factor needed for photosynthesis.Rate this question:
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- 45.
In xerophytic leaf the stomata are …….
- A.
On both surfaces
- B.
On upper surface
- C.
Absent from both surfaces
- D.
On lower surface
Correct Answer
D. On lower surfaceExplanation
Xerophytic plants are adapted to survive in arid or dry environments, where water is scarce. To minimize water loss through transpiration, xerophytic leaves have adaptations such as reduced leaf size, thick cuticle, and sunken stomata. Stomata are small openings on the leaf surface that allow for gas exchange, but also lead to water loss. By having stomata on the lower surface, xerophytic leaves can reduce exposure to direct sunlight and wind, which helps to conserve water and prevent excessive transpiration. Therefore, the correct answer is "On lower surface".Rate this question:
-
- 46.
The following diagram illustrates some vital processes that take place in some living organisms. These processes occur in which of the following organisms?
- A.
Chlorella alga
- B.
Bilharzia worms
- C.
Yeast fungus
- D.
Orobanche plant
Correct Answer
A. Chlorella algaExplanation
The diagram illustrates processes that occur in living organisms. Chlorella alga is the correct answer because it is a type of algae that undergoes photosynthesis, which is one of the vital processes shown in the diagram. Bilharzia worms are parasites that infect humans and animals, and their processes are not depicted in the diagram. Yeast fungus is a single-celled organism that undergoes fermentation, which is not shown in the diagram. Orobanche plant is a parasitic plant that obtains nutrients from other plants, and its processes are not represented in the diagram. Therefore, Chlorella alga is the only organism in the given options that matches the processes depicted in the diagram.Rate this question:
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- 47.
If NADP compound is absent during light reactions, ………
- A.
Splitting of water will not occur
- B.
Hydrogen will not be transferred to stroma
- C.
No fixation of CO2 will occur
- D.
Energy will not be carried to dark reactions
Correct Answer
C. No fixation of CO2 will occurExplanation
If NADP compound is absent during light reactions, it means that there will be no NADPH formed. NADPH is essential for the fixation of CO2 during the Calvin cycle, which is the dark reaction of photosynthesis. Without NADPH, the CO2 molecules cannot be converted into glucose or other organic compounds. Therefore, the absence of NADP compound during light reactions will result in no fixation of CO2.Rate this question:
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- 48.
In an experiment similar to that of Calvin, CO2 gas having O18 isotope was used and water having O16 was also used. Which of the following compounds are first produced?
- A.
Glucose contains O18
- B.
PGAL contains O18
- C.
Glucose contains O16
- D.
PGAL contains O16
Correct Answer
B. PGAL contains O18Explanation
In an experiment similar to that of Calvin, CO2 gas with O18 isotope was used. This isotope of oxygen would be incorporated into the compounds produced in the experiment. Since PGAL is an intermediate compound in the Calvin cycle, it would be one of the first compounds produced. Therefore, the correct answer is "PGAL contains O18".Rate this question:
-
- 49.
Which of the following compounds, its production inside the chloroplast will be affected by decreasing nitrogen element?
- A.
PGAL
- B.
Enzymes
- C.
Glucose
- D.
Starch
Correct Answer
B. EnzymesExplanation
The production of enzymes inside the chloroplast will be affected by decreasing nitrogen element. Nitrogen is an essential component of amino acids, which are the building blocks of proteins. Enzymes are proteins that catalyze biochemical reactions, so a decrease in nitrogen availability would result in a decrease in enzyme production.Rate this question:
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- 50.
The following figure represents the products of photosynthesis reactions. Which reactions occur in this stage?
- A.
Photophosphorylation
- B.
Reduction of CO2
- C.
Reduction of NADP
- D.
Splitting of water molecule
Correct Answer
B. Reduction of CO2Explanation
In the given figure, the products of photosynthesis reactions are represented. The reactions that occur in this stage are the reduction of CO2. This means that carbon dioxide is being converted into a different form during photosynthesis. The other options, photophosphorylation, reduction of NADP, and splitting of water molecule, are not represented in the figure and therefore do not occur in this stage.Rate this question:
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