Question 1

The chloroplast is a membrane-bound organelle that is surrounded by an outer membrane. Aside from the outer membrane of the chloroplast, how many other types of membranes can be found inside the chloroplast?

Accepted Answer

Inside the chloroplast, there are two additional types of membranes: the inner membrane and the thylakoid membrane.

Question 2

Inside the chloroplast, where are organic molecules made?

Accepted Answer

Organic molecules are made in the stroma of the chloroplast, where the Calvin cycle takes place, converting carbon dioxide and other compounds into glucose.

Question 3

Jan Baptista van Helmont did an important experiment related to photosynthesis. He weighed a small willow tree and a pot of soil. Jan then planted the tree in the pot. Over the course of five years, he added only water to the pot. At the end of five years, he weighed the tree and found that it had gained 74.4 kg. He weighed the soil, and it was only 57 g less. What do the results of this specific experiment demonstrate about what is needed for a plant to grow and increase its mass?

Accepted Answer

The experiment demonstrated that the increase in the tree's mass was not primarily from the soil, suggesting that plants gain mass from substances other than soil, such as water and carbon dioxide from the air.

Question 4

In his 1771 experiments, Joseph Priestly determined that plants added something to the air that allow an animal to survive. What do we now know that plants contribute to the air that is essential for animals (and other organisms)?

Accepted Answer

Plants contribute oxygen to the air through the process of photosynthesis, which is essential for the survival of animals and other aerobic organisms.

Question 5

The aquatic plant Elodea is commonly used to study photosynthesis. You put some Elodea in a test tube, shine light on the plant, and count the bubbles that were released under varying conditions. Which results would you expect to see in your analysis of photosynthetic rate?

Accepted Answer

As light intensity increases, photosynthesis generally increases, leading to more oxygen bubbles. At high light intensities, carbon dioxide becomes a limiting factor, so increasing its concentration can further increase the rate of photosynthesis and bubble production.

Question 6

F. F. Blackman performed experiments to investigate the effects of various factors on photosynthesis. In one of his experiments, Blackman found that if light intensity was low that photosynthesis could be accelerated by increasing the amount of light, but not by increasing the temperature or carbon dioxide concentration. What can you conclude from this specific experiment?

Accepted Answer

The experiment shows that increasing light intensity can accelerate photosynthesis when it is low, indicating that light is a crucial factor for photosynthesis.

Question 7

The aquatic plant Elodea is commonly used to study photosynthesis. You put some Elodea in a test tube filled with water containing radiolabeled oxygen (¹⁸O), shine light on the test tube, and measure the rate of photosynthesis by counting oxygen bubbles released. At the end of your experiment, you would find the most ¹⁸O in

Accepted Answer

During photosynthesis, water molecules are split, releasing oxygen gas. If the water contains radiolabeled oxygen, the released oxygen gas (O₂) will contain the radiolabeled oxygen.

Question 8

In plants, production of NADPH

Accepted Answer

NADPH production in plants occurs during the light-dependent reactions of photosynthesis, where electrons from water are used to reduce NADP+ to NADPH.

Question 9

Illuminated chloroplasts deprived of carbon dioxide

Accepted Answer

In the absence of carbon dioxide, the Calvin cycle cannot proceed, so glucose is not produced. However, the light reactions can still occur, leading to the accumulation of ATP and NADPH.

Question 10

Visible light has a wavelength range of:

Accepted Answer

Visible light has a wavelength range of approximately 400-740 nanometers, which is the range detectable by the human eye.

Question 11

-Based on a variety of experiments, it is known that the rate of photosynthesis is highest when wavelengths of light between 400 and 500 nm are used, and when wavelengths around 700 nm are used. What can you infer about the relative importance of chlorophyll a and b in photosynthesis?

Accepted Answer

Chlorophyll a and b absorb light most effectively in the blue (400-500 nm) and red (around 700 nm) regions, which are crucial for photosynthesis, indicating their essential role in the process.

Question 12

If chlorophyll a is blocked from absorbing light, what would be the effect on the ability of the plant to do photosynthesis?

Accepted Answer

Chlorophyll a is essential for the light-dependent reactions of photosynthesis, as it absorbs light energy to drive the process. Blocking it would decrease the plant's ability to perform these reactions.

Question 13

Fall leaf color on deciduous trees is a result of

Accepted Answer

As chlorophyll production ceases in the fall, the green color fades, revealing the accessory pigments like carotenoids and anthocyanins, which were already present but masked by the dominant green of chlorophyll.

Question 14

Why may eating carrots be useful for enhancing vision?

Accepted Answer

Carrots are rich in beta-carotene, which the body converts into vitamin A, a crucial component for producing rhodopsin, a pigment necessary for vision, especially in low-light conditions.

Question 15

In 1932, researchers Emerson and Arnold showed that the rate of photosynthesis saturated at a lower light intensity than expected for the number of individual chlorophyll molecules. From this observation they determined

Accepted Answer

Emerson and Arnold's observation led to the understanding that pigments are organized in clusters called photosystems, and the saturation they observed was due to the saturation of pigments in the reaction centers, not individual chlorophyll molecules.

Question 16

In photosynthesis, ATP is made by

Accepted Answer

ATP is made by chemiosmosis during the light reactions of photosynthesis, where a proton gradient is used to drive ATP synthesis.

Question 17

A tomato plant is mutated with gamma radiation. A cellular analysis reveals that ATP synthase complexes found in the thylakoid membrane are inserted backwards into the membrane. What is the most likely outcome of this error?

Accepted Answer

The ATP synthase complex needs to be oriented correctly to utilize the proton gradient across the thylakoid membrane to synthesize ATP. If inserted backwards, it cannot use the gradient effectively, preventing ATP production.

Question 18

As electrons travel from the primary electron acceptor in photosystem II, down the electron transport chain to photosystem I, they drive the movement of protons from the stroma into the thylakoid compartment. Why is the development of this chemical gradient useful to photosynthesis?

Accepted Answer

The proton gradient is used by ATP synthase to produce ATP, which is essential for the light-independent reactions (Calvin cycle) of photosynthesis.

Question 19

At night, the Calvin cycle in a C3 plant

Accepted Answer

The Calvin cycle does not require light directly and can continue at night if ATP, CO2, and NADPH, which are produced during the light-dependent reactions, are available.

Question 20

The ATP generated from cellular respiration is not sufficient to drive the Calvin cycle in plants, even if appropriate levels of NADPH and CO₂ are present. Why not?

Accepted Answer

Breaking down sugar to provide the energy needed to synthesize sugar would be a futile cycle, as it would negate the purpose of photosynthesis.

Quiz 8: Photosynthesis

The chloroplast is a membrane-bound organelle that is surrounded by an outer membrane. Aside from the outer membrane of the chloroplast, how many other types of membranes can be found inside the chloroplast?

Inside the chloroplast, where are organic molecules made?

In his 1771 experiments, Joseph Priestly determined that plants added something to the air that allow an animal to survive. What do we now know that plants contribute to the air that is essential for animals (and other organisms) ?

The aquatic plant Elodea is commonly used to study photosynthesis. You put some Elodea in a test tube, shine light on the plant, and count the bubbles that were released under varying conditions. Which results would you expect to see in your analysis of photosynthetic rate?

In plants, production of NADPH

Illuminated chloroplasts deprived of carbon dioxide

Visible light has a wavelength range of:

-Based on a variety of experiments, it is known that the rate of photosynthesis is highest when wavelengths of light between 400 and 500 nm are used, and when wavelengths around 700 nm are used. What can you infer about the relative importance of chlorophyll a and b in photosynthesis?

If chlorophyll a is blocked from absorbing light, what would be the effect on the ability of the plant to do photosynthesis?

Fall leaf color on deciduous trees is a result of

Why may eating carrots be useful for enhancing vision?

In 1932, researchers Emerson and Arnold showed that the rate of photosynthesis saturated at a lower light intensity than expected for the number of individual chlorophyll molecules. From this observation they determined

In photosynthesis, ATP is made by

A tomato plant is mutated with gamma radiation. A cellular analysis reveals that ATP synthase complexes found in the thylakoid membrane are inserted backwards into the membrane. What is the most likely outcome of this error?

As electrons travel from the primary electron acceptor in photosystem II, down the electron transport chain to photosystem I, they drive the movement of protons from the stroma into the thylakoid compartment. Why is the development of this chemical gradient useful to photosynthesis?

At night, the Calvin cycle in a C3 plant

The ATP generated from cellular respiration is not sufficient to drive the Calvin cycle in plants, even if appropriate levels of NADPH and CO₂ are present. Why not?

Quiz 8: Photosynthesis

The chloroplast is a membrane-bound organelle that is surrounded by an outer membrane. Aside from the outer membrane of the chloroplast, how many other types of membranes can be found inside the chloroplast?

Inside the chloroplast, where are organic molecules made?

In his 1771 experiments, Joseph Priestly determined that plants added something to the air that allow an animal to survive. What do we now know that plants contribute to the air that is essential for animals (and other organisms) ?

The aquatic plant Elodea is commonly used to study photosynthesis. You put some Elodea in a test tube, shine light on the plant, and count the bubbles that were released under varying conditions. Which results would you expect to see in your analysis of photosynthetic rate?

In plants, production of NADPH

Illuminated chloroplasts deprived of carbon dioxide

Visible light has a wavelength range of:

-Based on a variety of experiments, it is known that the rate of photosynthesis is highest when wavelengths of light between 400 and 500 nm are used, and when wavelengths around 700 nm are used. What can you infer about the relative importance of chlorophyll a and b in photosynthesis?

If chlorophyll a is blocked from absorbing light, what would be the effect on the ability of the plant to do photosynthesis?

Fall leaf color on deciduous trees is a result of

Why may eating carrots be useful for enhancing vision?

In 1932, researchers Emerson and Arnold showed that the rate of photosynthesis saturated at a lower light intensity than expected for the number of individual chlorophyll molecules. From this observation they determined

In photosynthesis, ATP is made by

A tomato plant is mutated with gamma radiation. A cellular analysis reveals that ATP synthase complexes found in the thylakoid membrane are inserted backwards into the membrane. What is the most likely outcome of this error?

As electrons travel from the primary electron acceptor in photosystem II, down the electron transport chain to photosystem I, they drive the movement of protons from the stroma into the thylakoid compartment. Why is the development of this chemical gradient useful to photosynthesis?

At night, the Calvin cycle in a C3 plant

The ATP generated from cellular respiration is not sufficient to drive the Calvin cycle in plants, even if appropriate levels of NADPH and CO2 are present. Why not?

The ATP generated from cellular respiration is not sufficient to drive the Calvin cycle in plants, even if appropriate levels of NADPH and CO₂ are present. Why not?