mastering bio ch 7

Which of the following equations represents photosynthesis?

6CO2 + 6H2O → C6H12O6 + 6O2

Which option properly summarizes the inputs and outputs of the Calvin cycle?

ATP + NADPH + 3CO 2 → G3P

What two molecules are produced by the light reactions and used to power the Calvin cycle?

ATP and NADPH

What connects the two photosystems in the light reactions?

An electron transport chain

In _________ plants, the first product of carbon fixation is the three-carbon compound 3-PGA formed in the Calvin cycle.

C3

In __________ plants, CO2 is first fixed into a four-carbon compound, which moves into bundle-sheath cells and releases CO2 to the Calvin cycle.

C4

In ___________plants, stomata are open at night, and CO2 is first fixed into a four-carbon compound, which releases CO2 to the Calvin cycle during the day.

CAM

Which gas contributes to both global warming and the deterioration of the ozone layer?

CFCs

What provides the carbon atoms that are incorporated into sugar molecules in the Calvin cycle?

Carbon dioxide (CO2)

Which statement regarding the light reactions is true?

Electrons are supplied to chlorophyll P680 as it reduces the primary electron acceptor.

In both respiration and photosynthesis, the potential energy of a(n) __________ is tapped to drive the phosphorylation of ADP to ATP. As H+ diffuses back through___________ (an enzyme complex embedded in the membrane), ATP is produced.

H+ concentration gradient, ATP synthase

What provides electrons for the light reactions?

H20

What is the potential benefit of photorespiration in plants?

It allows plant cells to reduce the buildup of oxygen gas without opening stomata.

Oxygen is the final electron acceptor for cellular respiration. What is the final electron acceptor in the light reactions of photosynthesis?

NADP+

In photosynthesis, the electrons come from water and end up in ___________

NADPH

What transports electrons from the light reactions to the Calvin cycle?

NADPH

When such plants close their stomata on hot, dry days to conserve water, _________builds up in the leaf and is added to RuBP in place of CO2. A two-carbon product of this reaction is broken down to CO2, consuming ATP and generating no sugar.

O2

One of the important waste products of photosynthesis is oxygen gas. Where does this oxygen gas come from?

Oxygen is released when water is broken down to extract electrons and protons for use in the light reactions.

Current evidence indicates that the process of photosynthesis arose more than three billion years ago. Its origin had a huge impact on existing organisms and on the physical characteristics of the biosphere. Which major physical change could be attributed to photosynthesis?

Photosynthesis drastically increased the oxygen content of the atmosphere.

Hydrogen is a likely candidate in the search for a replacement for petroleum. However, removing hydrogen from water requires the investment of a great deal of energy. Why are plants considered to be one step ahead in the utilization of hydrogen as an alternative fuel source?

Plant cells possess water-splitting enzymes.

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

The Calvin cycle depends on products of the light reactions.

A red chemical dye known as phenol red changes to yellow when CO2 is present. A small green plant seedling is placed in phenol red and then placed in the dark. Which of the following is most likely to occur?

The solution is red to begin with, and it will turn yellow because respiration is occurring.

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 before you left, the plant stored energy in the form of sugars or starch, and it was able to derive energy from those during your vacation.

ATP synthesis in both chloroplasts and mitochondria involves the process called _______

chemiosmosis

In which of the following organelles does photosynthesis take place?

chloroplasts

Which of the following are photoautotrophs?

corn stalks just before harvest

In both cellular respiration and photosynthesis, a(n) _________ built into a membrane pumps H+ across the membrane as electrons are passed from one electron carrier to the next in a series of redox reactions

electron transport chain

Photosynthesis is an __________ process in which carbon is __________, whereas cellular respiration is an __________ process in which carbon is __________.

endergonic : reduced : exergonic : oxidized

Incoming photons of light energy initiate photosynthesis by _____.

exciting electrons in pigment molecules within the photosystems, raising them to a higher energy level

In photosynthesis, __________drives electrons from a low-energy state in water to a high-energy state.

light energy

The thylakoid membranes bring together the components necessary to carry out the _____.

light reactions

Cellular respiration and photosynthesis are similar in that both involve _____.

oxidation-reduction (redox) reactions

In respiration, the electrons come from the oxidation of organic molecules, and __________is the final electron acceptor.

oxygen

The light reactions produce _____.

oxygen, NADPH, and ATP

The apparently wasteful process described in sentence 2 is called ________

photorespiration

In all three types of plants, the enzyme ________ brings CO2 into the Calvin cycle

rubisco

The light reactions take place in the _________ and the Calvin cycle takes place in the _________.

thylakoids; stroma

Both mitochondria and chloroplasts _____.

use an H+ gradient to produce ATP