Biology 1401 Chapter 8 Photosynthesis
Questions and Answers
- 1.
Carbon atoms of CO(2) are incorporated into organic molecules in a series of dark reactions called
- A.
Carbon reduction.
- B.
Carbon synthesis.
- C.
Carbon fixation.
- D.
Carbon activation.
- E.
Carbon oxidation.
Correct Answer
C. Carbon fixation.Explanation
Carbon fixation refers to the process in which carbon atoms from carbon dioxide (CO2) are incorporated into organic molecules during photosynthesis. This process occurs during the dark reactions (also known as the Calvin cycle) of photosynthesis, where energy from ATP and NADPH is used to convert CO2 into glucose and other organic compounds. Carbon reduction, carbon synthesis, carbon activation, and carbon oxidation are not accurate terms to describe this process.Rate this question:
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- 2.
Most plants incorporate carbon dioxide into sugars by means of a cycle of reactions called the
- A.
CAM cycle.
- B.
Carbon cycle.
- C.
Calvin cycle.
- D.
Krebs cycle.
- E.
Electron transport cycle.
Correct Answer
C. Calvin cycle.Explanation
The correct answer is Calvin cycle. The Calvin cycle is a series of reactions that takes place in the chloroplasts of plants, where carbon dioxide is converted into sugars. This cycle is also known as the light-independent reactions or the dark reactions, as it does not directly require light energy. The Calvin cycle is essential for the production of glucose and other sugars, which are used by plants for energy and growth.Rate this question:
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- 3.
Flattened sacs of internal membranes associated with photosynthesis are called
- A.
Chloroplasts.
- B.
Photosystems.
- C.
The stroma.
- D.
Thylakoids.
- E.
Cristae.
Correct Answer
D. Thylakoids.Explanation
Thylakoids are flattened sacs of internal membranes associated with photosynthesis. They are found within chloroplasts, which are the organelles responsible for photosynthesis in plants and algae. Thylakoids contain chlorophyll and other pigments that capture light energy, which is then used to convert carbon dioxide and water into glucose and oxygen. The other options, such as chloroplasts, photosystems, the stroma, and cristae, are not specifically associated with photosynthesis or the structure of thylakoids.Rate this question:
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- 4.
In green plant photosynthesis, the electron donor for the light dependent reaction is
- A.
Carbon dioxide.
- B.
Oxygen.
- C.
RuBP.
- D.
Chlorophyll II.
- E.
Water.
Correct Answer
E. Water.Explanation
In green plant photosynthesis, water serves as the electron donor for the light-dependent reaction. During this process, water molecules are split, releasing electrons that are used to generate energy in the form of ATP and NADPH. These energy-rich molecules are then used in the production of glucose during the light-independent reaction. Therefore, water is the correct answer as it provides the electrons necessary for the light-dependent reaction in photosynthesis.Rate this question:
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- 5.
In the dark reactions of photosynthesis, CO(2) is added to a five-carbon sugar-phosphate known as
- A.
Cyclic AMP.
- B.
NADH.
- C.
NAD+.
- D.
RuBP.
- E.
CAM.
Correct Answer
D. RuBP.Explanation
In the dark reactions of photosynthesis, CO(2) is added to a five-carbon sugar-phosphate known as RuBP (ribulose-1,5-bisphosphate). This process is called carbon fixation and occurs in the Calvin cycle. RuBP is regenerated at the end of each cycle, allowing the cycle to continue and more CO(2) to be fixed. Cyclic AMP, NADH, NAD+, and CAM are not directly involved in the dark reactions of photosynthesis.Rate this question:
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- 6.
Light consists of units of energy called
- A.
Electrons.
- B.
Photons.
- C.
Protons.
- D.
Neutrons.
- E.
Pigments.
Correct Answer
B. Photons.Explanation
Light consists of units of energy called photons. Photons are elementary particles that carry electromagnetic energy. When light is emitted or absorbed, it does so in discrete packets of energy called photons. These photons have properties of both particles and waves, and they travel at the speed of light. Electrons, protons, and neutrons are subatomic particles that do not carry energy in the form of light. Pigments, on the other hand, are substances that absorb certain wavelengths of light and reflect others, but they are not the fundamental units of energy in light.Rate this question:
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- 7.
Visible light has a wavelength range of
- A.
400-700 nanometers.
- B.
200-800 nanometers.
- C.
200-400 nanometers.
- D.
200-700 nanometers.
- E.
0.001-100,000 nanometers
Correct Answer
A. 400-700 nanometers.Explanation
Visible light refers to the portion of the electromagnetic spectrum that is visible to the human eye. It is composed of various colors, each corresponding to a specific wavelength. The given answer, 400-700 nanometers, is the correct range for the wavelength of visible light. This range includes the colors of the rainbow, with violet having the shortest wavelength (around 400 nm) and red having the longest wavelength (around 700 nm).Rate this question:
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- 8.
Which of the following has shortest wavelength by highest energy?
- A.
Infrared rays
- B.
X rays
- C.
Gamma rays
- D.
Ultra violet rays
- E.
Red light
Correct Answer
C. Gamma raysExplanation
Gamma rays have the shortest wavelength and highest energy among the given options. Gamma rays are a form of electromagnetic radiation that have the highest frequency and carry the most energy. They are produced by nuclear reactions and radioactive decay. In contrast, infrared rays, X rays, ultraviolet rays, and red light have longer wavelengths and lower energy compared to gamma rays.Rate this question:
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- 9.
Molecules that absorb light are called
- A.
Enzymes.
- B.
Electron carriers.
- C.
Pigments.
- D.
Photosynthesizers.
- E.
Absorbers.
Correct Answer
C. Pigments.Explanation
Molecules that absorb light are called pigments. Pigments are responsible for the absorption and reflection of light, giving objects their characteristic colors. They play a crucial role in various biological processes such as photosynthesis, where pigments like chlorophyll absorb light energy to convert it into chemical energy. Enzymes are proteins that catalyze biochemical reactions, electron carriers are molecules that transport electrons, and photosynthesizers and absorbers are not accurate terms to describe molecules that absorb light.Rate this question:
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- 10.
Chlorophyll b absorbs in green wavelengths of light that chlorophyll a cannot absorb. In this respect, chlorophyll b acts as
- A.
An accessory pigment.
- B.
An energizer for photosynthetic bacteria.
- C.
A light absorber in the green light.
- D.
A more efficient pigment.
Correct Answer
A. An accessory pigment.Explanation
Chlorophyll b is an accessory pigment because it absorbs light in the green wavelengths that chlorophyll a cannot absorb. Chlorophyll a is the primary pigment in photosynthesis, but chlorophyll b helps to broaden the range of light that can be absorbed and used for energy. Therefore, chlorophyll b acts as an accessory pigment, enhancing the efficiency of photosynthesis by capturing additional light energy.Rate this question:
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- 11.
The photosystem channels the excitation energy gathered by absorption of light by any one of the pigment molecules to a specific "reaction center chlorophyll," which in turn passes the energy to
- A.
Photosystem I.
- B.
Photosystem II.
- C.
The primary electron acceptor.
- D.
The secondary electron center.
- E.
Cytochrome.
Correct Answer
C. The primary electron acceptor.Explanation
The photosystem is responsible for capturing and channeling the excitation energy from absorbed light. This energy is transferred to a specific "reaction center chlorophyll," which then passes it on to the primary electron acceptor. The primary electron acceptor is a molecule that accepts the excited electrons and plays a crucial role in the electron transport chain, where the energy is used to generate ATP and NADPH. Therefore, the correct answer is the primary electron acceptor.Rate this question:
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- 12.
Which of the following is common to both cellular respiration and the light reactions of photosynthesis?
- A.
The transfer of electrons to glucose
- B.
The chemiosmotic formation of ATP
- C.
Oxygen is one of the byproducts
- D.
Mitochondria are essential organelles
- E.
Must have light
Correct Answer
B. The chemiosmotic formation of ATPExplanation
Both cellular respiration and the light reactions of photosynthesis involve the chemiosmotic formation of ATP. In cellular respiration, ATP is produced through oxidative phosphorylation in the mitochondria, while in the light reactions of photosynthesis, ATP is generated through photophosphorylation in the thylakoid membrane of chloroplasts. In both processes, ATP is synthesized using the energy from an electrochemical gradient created by the transfer of electrons through an electron transport chain. This commonality highlights the importance of ATP as an energy currency in both cellular respiration and photosynthesis.Rate this question:
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- 13.
Photosystem II absorbs photons that are slightly more energetic than photosystem I, because it has a pigment called
- A.
P (680).
- B.
P (700).
- C.
Chlorophyll I.
- D.
Chlorophyll II.
- E.
Retinal.
Correct Answer
A. P (680).Explanation
Photosystem II absorbs photons that are slightly more energetic than photosystem I because it has a pigment called P (680). This pigment absorbs light with a wavelength of 680 nanometers, which corresponds to the red part of the spectrum. This higher energy absorption allows photosystem II to initiate the electron transport chain and generate ATP through photophosphorylation. Photosystem I, on the other hand, has a pigment called P (700) which absorbs light with a wavelength of 700 nanometers, corresponding to the far-red part of the spectrum.Rate this question:
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- 14.
Photosystem II differs from photosystem I in that ____ is not made directly form the process.
- A.
ATP
- B.
NADH
- C.
NADPH
- D.
Carbohydrates
- E.
Water
Correct Answer
E. WaterExplanation
Photosystem II differs from photosystem I in that water is not made directly from the process. In photosystem II, water is split into oxygen, protons, and electrons during the light-dependent reactions. The electrons are then used to generate ATP and NADPH, which are essential for the Calvin cycle and carbohydrate synthesis. In contrast, photosystem I primarily produces NADPH, which is used in the light-independent reactions to reduce carbon dioxide and form carbohydrates.Rate this question:
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- 15.
The dark reactions of photosynthesis are those that
- A.
Convert chlorophylls into enzymes.
- B.
Convert enzymes into chlorophylls.
- C.
Convert water into hydrogen and oxygen.
- D.
Convert CO(2) into reduced molecules (sugars).
- E.
Only occur in the dark.
Correct Answer
D. Convert CO(2) into reduced molecules (sugars).Explanation
The dark reactions of photosynthesis refer to the Calvin cycle, which is the process that converts carbon dioxide (CO2) into reduced molecules such as sugars. This process does not require light directly, but it relies on the energy and ATP produced during the light-dependent reactions. Therefore, the correct answer is that the dark reactions convert CO2 into reduced molecules (sugars).Rate this question:
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- 16.
In dark reactions, when CO(2) is added to a molecule of RUBP the product is
- A.
Citric acid.
- B.
Glucose.
- C.
Glyceraldehyde-3-phosphate.
- D.
Phosphoglycerate.
- E.
Pyruvate.
Correct Answer
D. Phosphoglycerate.Explanation
In dark reactions, CO(2) is added to a molecule of RUBP (ribulose-1,5-bisphosphate) through a series of enzymatic reactions known as the Calvin cycle. The initial product formed is phosphoglycerate, which is a three-carbon molecule. This molecule is then converted into other compounds such as glucose or glyceraldehyde-3-phosphate, which are used in the synthesis of carbohydrates and other organic molecules. Therefore, the correct answer is phosphoglycerate.Rate this question:
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- 17.
The cyclic carbon fixation reactions are also known as the
- A.
Krebs cycle.
- B.
Calvin cycle.
- C.
Citric acid cycle.
- D.
Tri carboxylic acid cycle.
- E.
Blackman cycle.
Correct Answer
B. Calvin cycle.Explanation
The Calvin cycle is a set of cyclic carbon fixation reactions that occur in the stroma of chloroplasts during photosynthesis. It is named after Melvin Calvin, who discovered the pathway. The cycle involves a series of enzymatic reactions that convert carbon dioxide into glucose, using energy from ATP and NADPH produced during the light-dependent reactions. The other options mentioned in the question, such as the Krebs cycle, citric acid cycle, and tri carboxylic acid cycle, are all alternative names for the same metabolic pathway in cellular respiration, which is not related to the Calvin cycle. The Blackman cycle is not a recognized term in biology.Rate this question:
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- 18.
How many revolutions of the Calvin cycle are required to produce the sugar glucose?
- A.
2
- B.
3
- C.
4
- D.
5
- E.
6
Correct Answer
E. 6Explanation
The Calvin cycle is the process by which plants convert carbon dioxide into glucose. Each turn of the Calvin cycle produces one molecule of glucose. Therefore, six revolutions of the Calvin cycle are required to produce the sugar glucose.Rate this question:
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- 19.
In which part of the chloroplasts are the Calvin cycle enzymes located?
- A.
Stroma
- B.
Thylakoids
- C.
Grana
- D.
Envelope
- E.
Cristae
Correct Answer
A. StromaExplanation
The Calvin cycle enzymes are located in the stroma of the chloroplasts. The stroma is the fluid-filled space surrounding the thylakoids and is where the second stage of photosynthesis, the Calvin cycle, takes place. In this cycle, carbon dioxide is converted into glucose with the help of enzymes. Therefore, the stroma is where the enzymes necessary for this process are located.Rate this question:
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- 20.
The photosynthetic electron transport causes the accumulation of protons in which part of the chloroplast?
- A.
Matrix
- B.
Stroma
- C.
Envelope
- D.
Outer membrane
- E.
Internal thylakoid space
Correct Answer
E. Internal thylakoid spaceExplanation
The photosynthetic electron transport in chloroplasts involves the movement of electrons through a series of protein complexes located in the thylakoid membrane. As the electrons move through these complexes, protons are pumped from the stroma into the internal thylakoid space. This creates a concentration gradient of protons across the thylakoid membrane, which is essential for ATP synthesis during photosynthesis. Therefore, the correct answer is the internal thylakoid space.Rate this question:
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- 21.
Embedded in the thylakoid membrane and protuding as knobs form the outer surface into the stroma, there are
- A.
Enzymes that fix carbon dioxide.
- B.
Proton channels that synthesize ATP.
- C.
Chlorophyll a and b.
- D.
P(680) and P(700).
- E.
Specialized bundle sheath cells.
Correct Answer
B. Proton channels that synthesize ATP.Explanation
The correct answer is "proton channels that synthesize ATP." This is because the statement mentions that these channels are embedded in the thylakoid membrane and protrude as knobs into the stroma. These proton channels are part of the process of photosynthesis, where they create a proton gradient across the thylakoid membrane. This gradient is then used by ATP synthase to produce ATP, which is the energy currency of the cell.Rate this question:
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- 22.
What products of light reactions of phtosynthesis are use in the Calvin cycle?
- A.
Oxygen and protons
- B.
Carbon dioxide and water
- C.
ATP and NADPH
- D.
ADP and NADP
- E.
Glucose and oxygen
Correct Answer
C. ATP and NADPHExplanation
In the light reactions of photosynthesis, ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate) are produced. These products are then utilized in the Calvin cycle, also known as the dark reactions, to convert carbon dioxide into glucose. ATP provides the energy required for the synthesis of glucose, while NADPH acts as a reducing agent to transfer high-energy electrons to the Calvin cycle. Therefore, ATP and NADPH are the products of light reactions that are used in the Calvin cycle.Rate this question:
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- 23.
Most of the atmospheric oxygen occurs as a result of phtosynthesis. From which of the following molecules is the oxygen derived?
- A.
Water
- B.
Carbon dioxide
- C.
Glucose
- D.
Chlorophyll
Correct Answer
A. WaterExplanation
The correct answer is water. During photosynthesis, plants use sunlight to convert carbon dioxide and water into glucose and oxygen. The oxygen released during this process comes from the splitting of water molecules.Rate this question:
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- 24.
If they thylakoid membrane became leaky to ions, what would you predict to be the result on the light reaction?
- A.
It would stop ATP production
- B.
It would stop NADPH production
- C.
It would stop oxidation of H(2)O
- D.
It would stop CO(2) fixation
Correct Answer
A. It would stop ATP productionExplanation
If the thylakoid membrane became leaky to ions, it would disrupt the electrochemical gradient necessary for ATP synthesis during the light reaction. This gradient is established by the movement of ions across the thylakoid membrane, and if the membrane becomes leaky, the ions will not be able to build up on one side of the membrane, leading to a halt in ATP production.Rate this question:
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