Question 1

The addition of oxygen instead of carbon dioxide to RuBP results in

Accepted Answer

The addition of oxygen instead of carbon dioxide to RuBP is known as photorespiration. This occurs when there is a shortage of carbon dioxide in the leaf and oxygen becomes the substrate for the enzyme RuBisCO, leading to the formation of a toxic compound that must be detoxified by the plant. Photorespiration is an inefficient process and reduces the efficiency of photosynthesis.

Question 2

ATP and NADPH

Accepted Answer

ATP and NADPH are used as energy carriers during the Calvin cycle to power the synthesis of sugars. This happens in the stroma of the chloroplasts, where the Calvin cycle takes place.

Question 3

What is the main adaptive advantage of the C₄ and CAM photosynthesis strategies over the C₃ strategy?

Accepted Answer

C₄ and CAM photosynthesis strategies are adaptations to arid conditions, allowing plants to efficiently fix carbon and synthesize glucose while minimizing water loss.

Question 4

In photosynthesis, the chemiosmotic production of ATP

Accepted Answer

The chemiosmotic production of ATP in photosynthesis involves the movement of protons across a membrane (in this case, the thylakoid membrane) to create a proton gradient that is used to generate ATP. This is similar to the production of ATP in mitochondria through oxidative phosphorylation.

Question 5

Photorespiration

Accepted Answer

Photorespiration is thought to be an evolutionary relic from when atmospheric O2 levels were low. This is because it can occur when rubisco (the enzyme responsible for carbon fixation in photosynthesis) binds with O2 instead of CO2, leading to the production of a toxic compound that must be broken down in a process known as photorespiration. With lower atmospheric O2 levels, the likelihood of O2 binding to rubisco was lower, so photorespiration was not as necessary. As atmospheric O2 levels increased, photorespiration became more common as a way for plants to deal with this problem. However, photorespiration is not beneficial to the plant because it uses energy and does not produce glucose.

Question 6

It has been argued that cutting old-growth forests and replacing them with plantations of young trees would help to alleviate the threat of global greenhouse warming. What important fact does this argument ignore?

Accepted Answer

Cutting old-growth forests releases stored carbon into the atmosphere, contributing to CO2 levels, while young plantations take time to sequester carbon effectively.

Question 7

Plants use sugars as a

Accepted Answer

Plants use sugars as a fuel for cellular respiration, which generates ATP for energy. Sugars are also used as starting material for making other organic molecules, such as amino acids, nucleotides, and lipids. While sugars are necessary for the Calvin cycle in photosynthesis, they are not used as a source of electrons for chemiosmosis.

Question 8

Photosystem II

Accepted Answer

Photosystem II passes electrons to photosystem I as part of the light-dependent reactions of photosynthesis, where water is split to replace the electrons, producing oxygen as a by-product, not CO2.

Question 9

Which of the following statements about the greenhouse effect is true?

Accepted Answer

The greenhouse effect is caused by the trapping of heat in the earth's atmosphere by greenhouse gases, such as carbon dioxide, methane, and water vapor. Burning fossil fuels releases large amounts of carbon dioxide into the atmosphere, which enhances the greenhouse effect and contributes to global warming. Deforestation can actually exacerbate the greenhouse effect as trees absorb carbon dioxide during photosynthesis. The greenhouse effect is causing an increase in average temperature on the planet, not a decrease. It is also not known to decrease plant growth, as plants rely on carbon dioxide for photosynthesis.

Question 10

The ultimate source of all the food we eat and the oxygen we breathe is

Accepted Answer

Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize foods with the help of carbon dioxide and water. This process produces the ultimate source of all the food we eat and the oxygen we breathe. Cellular respiration and anaerobic metabolism are processes that use the products of photosynthesis (sugar and oxygen) to produce energy for the cells. Glycolysis is a part of cellular respiration but is not the ultimate source of food and oxygen.

Question 11

Global warming due to the greenhouse effect may be

Accepted Answer

Photosynthesis removes carbon dioxide from the atmosphere, which can help to reduce the greenhouse effect and therefore help to mitigate global warming. While burning fossil fuels can also remove oxygen from the atmosphere, this is not a viable solution to reducing global warming as it has many negative environmental and health impacts. Additionally, global warming is not part of the normal cycle for the planet and is primarily caused by human activities.

Question 12

In chloroplasts, ATP synthase

Accepted Answer

ATP synthase is an enzyme that catalyzes the synthesis of ATP from ADP and inorganic phosphate during oxidative phosphorylation. In chloroplasts, ATP synthase also functions in the production of ATP in the process of photosynthesis.

Question 13

To produce one glucose, the Calvin cycle needs to be run ________ times.

Accepted Answer

The Calvin cycle needs to be run six times to produce one glucose molecule. This is because each turn of the cycle fixes one molecule of CO2, and it takes six molecules of CO2 to produce one six-carbon glucose molecule.

Question 14

In photophosphorylation, energy from electron flow is used to transport ________ from the ________ to the thylakoid compartment, generating a concentration gradient of ________.

Accepted Answer

In photophosphorylation, energy from electron flow is used to transport protons (H+) from the stroma to the thylakoid compartment, generating a concentration gradient of protons (H+).

Question 15

Mitochondria transfer ________ energy from ________ to ATP; chloroplasts transform ________ energy into the chemical energy of ATP.

Accepted Answer

Mitochondria transfer chemical energy from food to ATP, while chloroplasts transform light energy into the chemical energy of ATP.

Question 16

The electrons lost from the reaction center of photosystem II are replaced by electrons from

Accepted Answer

The electrons lost from the reaction center of photosystem II are replaced by electrons from water molecules. During the light-dependent reactions of photosynthesis, water is oxidized, producing oxygen gas and hydrogen ions. The electrons from water are then used to replace the electrons lost from photosystem II.

Question 17

Photosynthetic organisms derive their carbon from

Accepted Answer

Photosynthetic organisms, such as plants, algae, and cyanobacteria, obtain their carbon from carbon dioxide through the process of photosynthesis.

Question 18

Photophosphorylation during photosynthesis differs from oxidative phosphorylation during cellular respiration in that

Accepted Answer

Photophosphorylation during photosynthesis differs from oxidative phosphorylation in cellular respiration mainly in the final electron acceptor used. In photophosphorylation, the final electron acceptor is NADP+ (which becomes NADPH), whereas in oxidative phosphorylation, the final electron acceptor is oxygen (which becomes water).

Question 19

Plant cells

Accepted Answer

Plant cells have both mitochondria and chloroplasts. Mitochondria are responsible for cellular respiration, which produces energy for the cell. Chloroplasts contain chlorophyll and are responsible for photosynthesis, which converts sunlight into energy for the cell. Both organelles play important roles in the functioning of plant cells.

Question 20

The Calvin cycle constructs ________, an energy-rich molecule that a plant cell can then use to make glucose or other organic molecules.

Accepted Answer

The Calvin cycle is the process by which plants and algae convert carbon dioxide from the atmosphere into organic molecules, particularly glucose. One of the key products of the Calvin cycle is G3P (glyceraldehyde-3-phosphate), an energy-rich molecule that the plant can use to make glucose or other organic molecules. While ATP and NADH are involved in the Calvin cycle as energy carriers, they are not the ultimate product of the cycle. Carbon dioxide is a reactant in the cycle and is not a product.

Quiz 7: Photosynthesis: Using Light to Make Food

The addition of oxygen instead of carbon dioxide to RuBP results in

ATP and NADPH

What is the main adaptive advantage of the C₄ and CAM photosynthesis strategies over the C₃ strategy?

In photosynthesis, the chemiosmotic production of ATP

Photorespiration

It has been argued that cutting old-growth forests and replacing them with plantations of young trees would help to alleviate the threat of global greenhouse warming. What important fact does this argument ignore?

Plants use sugars as a

Photosystem II

Which of the following statements about the greenhouse effect is true?

The ultimate source of all the food we eat and the oxygen we breathe is

Global warming due to the greenhouse effect may be

In chloroplasts, ATP synthase

To produce one glucose, the Calvin cycle needs to be run ________ times.

In photophosphorylation, energy from electron flow is used to transport from the to the thylakoid compartment, generating a concentration gradient of .

Mitochondria transfer energy from to ATP; chloroplasts transform energy into the chemical energy of ATP.

The electrons lost from the reaction center of photosystem II are replaced by electrons from

Photosynthetic organisms derive their carbon from

Photophosphorylation during photosynthesis differs from oxidative phosphorylation during cellular respiration in that

Plant cells

The Calvin cycle constructs ________, an energy-rich molecule that a plant cell can then use to make glucose or other organic molecules.

Quiz 7: Photosynthesis: Using Light to Make Food

The addition of oxygen instead of carbon dioxide to RuBP results in

ATP and NADPH

What is the main adaptive advantage of the C4 and CAM photosynthesis strategies over the C3 strategy?

In photosynthesis, the chemiosmotic production of ATP

Photorespiration

It has been argued that cutting old-growth forests and replacing them with plantations of young trees would help to alleviate the threat of global greenhouse warming. What important fact does this argument ignore?

Plants use sugars as a

Photosystem II

Which of the following statements about the greenhouse effect is true?

The ultimate source of all the food we eat and the oxygen we breathe is

Global warming due to the greenhouse effect may be

In chloroplasts, ATP synthase

To produce one glucose, the Calvin cycle needs to be run ________ times.

In photophosphorylation, energy from electron flow is used to transport ________ from the ________ to the thylakoid compartment, generating a concentration gradient of ________.

Mitochondria transfer ________ energy from ________ to ATP; chloroplasts transform ________ energy into the chemical energy of ATP.

The electrons lost from the reaction center of photosystem II are replaced by electrons from

Photosynthetic organisms derive their carbon from

Photophosphorylation during photosynthesis differs from oxidative phosphorylation during cellular respiration in that

Plant cells

The Calvin cycle constructs ________, an energy-rich molecule that a plant cell can then use to make glucose or other organic molecules.

What is the main adaptive advantage of the C₄ and CAM photosynthesis strategies over the C₃ strategy?

In photophosphorylation, energy from electron flow is used to transport from the to the thylakoid compartment, generating a concentration gradient of .

Mitochondria transfer energy from to ATP; chloroplasts transform energy into the chemical energy of ATP.