chapter 10 biology

Carbon dioxide and oxygen enter and exit a leaf by diffusion. Which structure(s) on a leaf allow(s) this process to happen?

Stomata

Where does the Calvin cycle of photosynthesis occur?

Stroma

During the Calvin cycle, what happens during the carbon fixation phase?

The Calvin cycle incorporates each CO2 molecule, one at a time, by attaching it to a five-carbon sugar named ribulose bisphosphate.

The reactions of the Calvin cycle are not directly dependent on light, but they usually do not occur at night. Why?

The Calvin cycle requires products only produced when the photosystems are illuminated.

Which of the following statements correctly describes the difference in carbon fixation between C3 and C4 plants?

The first product of carbon fixation in C4 plants is a four-carbon compound instead of a three-carbon compound.

During which process is molecular oxygen produced in photosynthesis?

The light reactions by linear electron flow

The Calvin cycle could not occur without the light reactions. Which of the following statements describes why this is the case?

ATP and NADPH produced in the light reactions provide the energy for the production of sugars in the Calvin cycle.

The light reactions of photosynthesis supply the Calvin cycle with __________.

ATP and NADPH.

G3P is used in which of the following processes?

All of the listed processes can use G3P.

Which of the following statements is a correct distinction between autotrophs and heterotrophs?

Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic.

Of the following, which occurs during the Calvin cycle?

CO2 is reduced.

What property of the pigment chlorophyll makes it appear green?

Chlorophyll absorbs all of the visible spectrum of light except green, which it reflects.

Which of the following processes occurs during the second phase, the reduction phase, of the Calvin cycle?

G3P production

The light reactions of photosynthesis generate high-energy electrons, which end up in __________. The light reactions also produce __________ and __________.

NADPH; ATP; oxygen

In the light reactions of photosynthesis, ATP is produced by photophosphorylation. Which of the listed processes is most similar to photophosphorylation?

Oxidative phosphorylation in cellular respiration

Why are most autotrophs referred to as the producers of the biosphere?

They are the ultimate sources of organic compounds for all nonautotrophic organisms.

How does carbon dioxide enter the leaf?

Through the stomata

The light reactions of photosynthesis use chemiosmosis to produce ATP that will be used in the Calvin cycle. The electrochemical gradient that drives this chemiosmosis is formed across which structure(s)?

Thylakoid membrane

Chlorophyll molecules are in which part of the chloroplast?

Thylakoid membranes

Where do the electrons entering photosystem II come from?

Water

Metabolic pathways are typically redox processes. In photosynthesis, what molecule is oxidized and what molecule is reduced?

Water is oxidized and carbon dioxide is reduced.

You have a large, healthy philodendron that you carelessly leave in total darkness while you are away on vacation. You are surprised to find that it is still alive when you return. What has the plant been using for an energy source while in the dark?

While it did have access to light, the plant stored energy in the form of sugars or starch, and it was able to derive energy from the stored molecules during your vacation.

The most important role of pigments in photosynthesis is to __________.

capture light energy

In photosynthesis, plants use carbon from __________ to make sugar and other organic molecules.

carbon dioxide

The energy used to produce ATP in the light reactions of photosynthesis comes from __________.

movement of H+ through a membrane

When chloroplast pigments absorb light, __________.

their electrons become excited

The light reactions of photosynthesis occur in the __________.

thylakoids

Both mitochondria and chloroplasts __________.

use chemiosmosis to produce ATP

The source of the oxygen produced by photosynthesis has been identified through experiments using radioactive tracers. The oxygen comes from __________.

water