3.3

After 3-PGA is phosphorylated, it is reduced by _____. a. NADPH b. ATP c. CO2 d. NADP+ e. ADP

A

Chlorophylls absorb most light in which colors of the visible range? a. blue and red b. violet and red c. green and red d. green and blue

A

What is the importance of the light-independent reactions in terms of carbon flow in the biosphere? a. The light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars. b. The light-independent reactions turn glucose, a sugar, into CO2 gas. c. The light-independent reactions use CO2 to make ATP. d. The light-independent reactions turn sugar into ATP for energy.

A

Which of the following molecules is the primary product of photosystem I? a. NADPH b. Oxygen c. ATP d. Carbon dioxide

A

Which set of reactions uses H2O and produces O2? a. The light-dependent reactions b. The light-independent reactions

A

The electrons of photosystem II are excited and transferred to electron carriers. From which molecule or structure do the photosystem II replacement electrons come? a. photosystem I b. water c. oxygen d. the electron carrier, plastocyanin

B

The process of photosynthesis probably originated _____. a. three separate times during evolution b. in prokaryotes c. in plants d. in fungi

B

What is the biological significance of the light-independent reactions of photosynthesis? a. They convert ATP to sugar. b. They convert carbon dioxide to sugar. c. They generate ATP and NADPH. d. They make oxygen.

B

Which molecule is regenerated in the regeneration phase of the Calvin cycle? Without regeneration of this molecule, the Calvin cycle would stop. a. 3-phosphoglycerate b. RuBP c. ATP d. G3P

B

Which of these equations best summarizes photosynthesis? a. H2O → 2 H+ + 1/2 O2 + 2e- b. 6 CO2 + 6 H2O → C6H12O6 + 6 O2 c. C6H12O6 + 6 O2 → 6 CO2 + 12 H2O d. 6 CO2 + 6 O2 → C6H12O6 + 6 H2O e. C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy

B

Which process produces oxygen? a. Cellular respiration b. Photosynthesis

B

How many carbon dioxide molecules must be added to RuBP to make a single molecule of glucose? a. 2 b. 4 c. 6 d. 8 e. 10

C

In autumn, the leaves of deciduous trees change colors. This is because chlorophyll is degraded and _____. a. the degraded chlorophyll changes into many other colors b. water supply to the leaves has been reduced c. carotenoids and other pigments are still present in the leaves d. sugars are sent to most of the cells of the leaves

C

In the Calvin cycle, how many ATP molecules are required to regenerate RuBP from five G3P molecules? a. 1 b. 5 c. 3 d. 2 e. 4

C

Reactions that require CO2 take place in _____. a. the light reactions alone b. both the light reactions and the Calvin cycle c. the Calvin cycle alone d. the chloroplast, but not as part of photosynthesis e. neither the light reactions nor the Calvin cycle

C

The figure shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different? a. Bright sunlight destroys photosynthetic pigments. b. Green and yellow wavelengths inhibit the absorption of red and blue wavelengths. c. Other pigments absorb light in addition to chlorophyll a. d. Oxygen given off during photosynthesis interferes with the absorption of light. e. Aerobic bacteria take up oxygen, which changes the measurement of the rate of photosynthesis.

C

What is the main purpose of light-dependent reactions of photosynthesis? a. to generate oxygen by "splitting" H2O b. to produce NADPH for use in respiration c. to produce NADPH and ATP d. to use ATP to make glucose

C

When oxygen is released as a result of photosynthesis, it is a direct by-product of _____. a. reducing NADP+ b. the electron transfer system of photosystem II c. splitting water molecules d. the electron transfer system of photosystem I e. chemiosmosis

C

Which of the following statements best describes the relationship between the light-dependent and light-independent reactions of photosynthesis? a. The light-dependent reactions pass electrons through an electron transport chain to the light-independent reactions. b. The light-dependent reactions produce carbon dioxide, which is then used by the light-independent reactions. c. The light-dependent reactions produce ATP and NADPH, which are then used by the light-independent reactions. d. The light-independent reactions release energy, and the light-dependent reactions require energy.

C

Why are there several structurally different pigments in the reaction centers of photosystems? a. Excited electrons must pass through several pigments before they can be transferred to electron acceptors of the electron transport chain. b. They enable the plant to absorb more photons from light energy, all of which are at the same wavelength. c. This arrangement enables the plant to absorb light energy of a variety of wavelengths. d. They enable the reaction center to excite electrons to a higher energy level.

C

In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during _____. a. respiration only b. photosynthesis only c. neither photosynthesis nor respiration d. photosynthesis and respiration e. photorespiration only

D

In plants, reduction of NADP+ occurs during _____. a. photosynthesis and respiration b. respiration c. neither photosynthesis nor respiration d. photosynthesis

D

Photorespiration _____. a. generates ATP and sugars and consumes oxygen and carbon dioxide b. generates oxygen and consumes ATP, carbon dioxide, and sugars c. consumes carbon dioxide and generates ATP, sugars, and oxygen d. generates carbon dioxide and consumes ATP and oxygen

D

The chemiosmotic process in chloroplasts involves the _____. a. formation of glucose, using carbon dioxide, NADPH, and ATP b. movement of water by osmosis into the thylakoid space from the stroma c. reduction of water to produce ATP d. establishment of a proton gradient across the thylakoid membrane e. diffusion of electrons through the thylakoid membrane

D

The light reactions of photosynthesis use _____ and produce _____. a. NADPH ... oxygen b. carbon dioxide ... sugar c. carbon dioxide ... oxygen d. water ... NADPH e. NADPH ... NADP+

D

The rate of O2 production by the light reactions varies with the intensity of light because light is required as the energy source for O2 formation. Thus, lower light levels generally mean a lower rate of O2 production. In addition, lower light levels also affect the rate of CO2 uptake by the Calvin cycle. This is because the Calvin cycle needs the ATP and NADPH produced by the light reactions. In this way, the Calvin cycle depends on the light reactions. But is the inverse true as well? Do the light reactions depend on the Calvin cycle? Suppose that the concentration of CO2 available for the Calvin cycle decreased by 50% (because the stomata closed to conserve water). Which statement correctly describes how O2 production would be affected? (Assume that the light intensity does not change.) a. The rate of O2 production would decrease because the rate of G3P production by the Calvin cycle would decrease. b. The rate of O2 production would remain the same because the light intensity did not change. c. The rate of O2 production would remain the same because the light reactions are independent of the Calvin cycle. d. The rate of O2 production would decrease because the rate of ADP and NADP+ production by the Calvin cycle would decrease.

D

Which of the events listed below occurs in the light reactions of photosynthesis? a. NADP is produced. b. NADPH is reduced to NADP+. c. Carbon dioxide is incorporated into PGA. d. Light is absorbed and funneled to reaction-center chlorophyll a. e. ATP is phosphorylated to yield ADP.

D

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle? a. electrons and H+ b. ADP, P symbol in circlei, and NADP+ c. CO2 and glucose d. ATP and NADPH e. H2O and O2

D

Carbon fixation involves the addition of carbon dioxide to _____. a. NADPH b. G3P c. 3-PGA d. Rubisco e. RuBP

E

Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants? a. They serve as accessory pigments to increase light absorption. b. They reflect orange light and enhance red light absorption by chlorophyll. c. They shield the sensitive chromosomes of the plant from harmful ultraviolet radiation. d. They take up and remove toxins from the groundwater. e. They protect against oxidative damage from excessive light energy.

E

In a plant cell, where are the ATP synthase complexes located? a. thylakoid membrane only b. plasma membrane only c. thylakoid membrane and plasma membrane d. inner mitochondrial membrane only e. thylakoid membrane and inner mitochondrial membrane

E

Where does the calvin cycle occur?

E

Which of the following statements best describes the relationship between photosynthesis and respiration? a. Respiration runs the biochemical pathways of photosynthesis in reverse. b. Photosynthesis is catabolic; respiration is anabolic. c. ATP molecules are produced in photosynthesis but not in aerobic respiration. d. Photosynthesis occurs only in plants; respiration occurs only in animals. e. Photosynthesis stores energy in complex organic molecules; respiration releases energy from complex organic molecules

E

True or false? The light-dependent reactions of photosynthesis use water and produce oxygen.

True