ch.10

24) Which of the following are directly associated with photosystem I?

A) receiving electrons from the thylakoid membrane electron transport chain

60) Photorespiration _____.

A) generates carbon dioxide and consumes ATP and oxygen

10) What wavelength of light in the figure is most effective in driving photosynthesis?

A) 420 mm

58) Which of the following statements is true concerning the accompanying figure?

A) It represents a C4 photosynthetic system.

57) Compared to C3 plants, C4 plants _____.

A) can continue to fix CO2 even at lower CO2 concentrations and higher oxygen concentrations

18) In autumn, the leaves of deciduous trees change colors. This is because chlorophyll is degraded and _____.

A) carotenoids and other pigments are still present in the leaves

54) CAM plants keep stomata closed in the daytime, thus reducing loss of water. They can do this because they _____.

A) fix CO2 into organic acids during the night

7) When oxygen is released as a result of photosynthesis, it is a direct by-product of _____.

A) splitting water molecules

44) Where does the Calvin cycle take place?

A) stroma of the chloroplast

37) In a plant, the reactions that produce molecular oxygen (O2) take place in _____.

A) the light reactions alone

4) Early investigators thought the oxygen produced by photosynthetic plants came from carbon dioxide. In fact, it comes from _____.

A) water

16) Why are there several structurally different pigments in the reaction centers of photosystems?

B) This arrangement enables the plant to absorb light energy of a variety of wavelengths.

53) Why are C4 plants able to photosynthesize with no apparent photorespiration?

B) They use PEP carboxylase to initially fix CO2.

47) Refer to the figure. If the carbon atom of each of the incoming CO2 molecules is labeled with a radioactive isotope of carbon, which organic molecules will be radioactively labeled after one cycle?

B) B, C, D, and E

Theodor W. Engelmann illuminated a filament of algae with light that passed through a prism, thus exposing different segments of algae to different wavelengths of light. He added aerobic bacteria and then noted in which areas the bacteria congregated. He noted that the largest groups were found in the areas illuminated by the red and blue light. 11) What did Engelmann conclude about the congregation of bacteria in the red and blue areas?

B) Bacteria congregated in these areas because these areas had the most oxygen being released.

52) What would be the expected effect on plants if the atmospheric CO2 concentration was doubled?

B) C3 plants would have faster growth; C4 plants would be minimally affected.

49) Which of the following sequences correctly represents the flow of electrons during photosynthesis?

B) H2O → NADPH → Calvin cycle

17) If pigments from a particular species of plant are extracted and subjected to paper chromatography, which of the following is most likely?

B) Paper chromatography would separate the pigments from a particular plant into several bands.

31) Which of the following statements best describes the relationship between photosynthesis and respiration?

B) Photosynthesis stores energy in complex organic molecules; respiration releases energy from complex organic molecules

34) What is the relationship between the wavelength of light and the quantity of energy per photon?

B) They are inversely related.

36) Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants?

B) They protect against oxidative damage from excessive light energy.

23) In the thylakoid membranes, the pigment molecules in a light-harvesting complex _____.

B) absorb and transfer light energy to the reaction-center chlorophyll

41) A gardener is concerned that her greenhouse is getting too hot from too much light and seeks to shade her plants with colored translucent plastic sheets, the color of which allows passage of only that wavelength. What color should she use to reduce overall light energy but still maximize plant growth?

B) blue

14) Suppose a plant has a unique photosynthetic pigment and the leaves of this plant appear to be reddish yellow. What wavelengths of visible light are absorbed by this pigment?

B) blue and violet

59) Referring to the accompanying figure, oxygen would inhibit the CO2 fixation reactions in _____.

B) cell II only

38) The accumulation of free oxygen in Earth's atmosphere began with the origin of _____.

B) cyanobacteria using photosystem II

1) The process of photosynthesis probably originated _____.

B) in prokaryotes

39) In its mechanism, photophosphorylation is most similar to _____.

B) oxidative phosphorylation in cellular respiration

50) Which of the following does NOT occur during the Calvin cycle?

B) release of oxygen

30) In mitochondria, chemiosmosis moves protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis moves protons from the _____.

B) stroma to the thylakoid space

25) Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be to _____.

B) test for liberation of O2 in the light

26) What are the products of linear electron flow?

C) ATP and NADPH

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

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

55) The alternative pathways of photosynthesis using the C4 or CAM systems are said to be compromises. Why?

C) Both minimize photorespiration but expend more ATP during carbon fixation.

20) As electrons are passed through the system of electron carriers associated with photosystem II, they lose energy. What happens to this energy?

C) It is used to establish and maintain a proton gradient.

21) The final electron acceptor associated with photosystem I is _____.

C) NADP

9) The figure shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?

C) Other pigments absorb light in addition to chlorophyll a.

48) Refer to the figure. To identify the molecule that accepts CO2, Calvin and Benson manipulated the carbon-fixation cycle by either cutting off CO2 or cutting off light from cultures of photosynthetic algae. They then measured the concentrations of various metabolites immediately following the manipulation. How would these experiments help identify the CO2 acceptor?

C) The CO2 acceptor concentration would increase when the CO2 is cut off, but decrease when the light is cut off.

56) If plant gene alterations cause plants to be deficient in photorespiration, what would most probably occur?

C) There would be more light-induced damage to the cells.

A spaceship is designed to support animal life for a multiyear voyage to the outer planets of the solar system. Plants will be grown to provide oxygen and to recycle carbon dioxide. Since the spaceship will be too far from the sun for photosynthesis, an artificial light source will be needed. 13) What wavelengths of light should be used to maximize plant growth with a minimum of energy expenditure?

C) a mixture of blue and red light

27) As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find that 30,000 molecules of ATP were consumed, but only 20,000 molecules of NADPH were consumed. Where did the extra ATP molecules come from?

C) cyclic electron flow

15) Halobacterium has a photosynthetic membrane that appears purple. Its photosynthetic action spectrum is the inverse of the action spectrum for green plants. (That is, the Halobacterium action spectrum has a peak where the green plant action spectrum has a trough.) What wavelengths of light do the Halobacterium photosynthetic pigments absorb?

C) green and yellow

3) Plants photosynthesize _____.

C) only in the light but respire in light and dark

32) In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during _____.

C) photosynthesis and respiration

46) In the process of carbon fixation, RuBP attaches a CO2 to produce a six-carbon molecule, which is then split to produce two molecules of 3-phosphoglycerate. After phosphorylation and reduction produces glyceraldehyde 3-phosphate (G3P), what more needs to happen to complete the Calvin cycle?

C) regeneration of RuBP

28) Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will most directly affect the _____.

C) synthesis of ATP

29) In a plant cell, where are the ATP synthase complexes located?

C) thylakoid membrane and inner mitochondrial membrane

22) The electrons of photosystem II are excited and transferred to electron carriers. From which molecule or structure do the photosystem II replacement electrons come?

C) water

12) An outcome of Engelmann's experiment was to help determine the relationship between _____.

C) wavelengths of light and the rate of photosynthesis

43) Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?

D) ATP and NADPH

19) What event accompanies energy absorption by chlorophyll (or other pigment molecules of the antenna complex)?

D) An electron is excited.

61) Students conducted an experiment to determine the effect of light intensity on the rate of photosynthesis. They punched 40 leaf disks from spinach leaves and used a syringe partially filled with water to pull the gases from the leaf disks so that all leaf disks sunk to the bottom of the syringe. Ten (10) leaf disks from the syringe were placed in each of four cups and covered with 50 ml of the solutions as indicated below. All leaf disks were resting on the bottom of the cups when the experiment began. The volume of liquid in each cup and the temperature of the solutions were held constant. All cups were placed 0.5 meters from the designated light source. A large beaker of water was placed between the light and the cups to act as a heat sink to prevent a change in temperature. At the end of 10 minutes, the number of disks floating in each cup was recorded. Use your knowledge of the mechanism of photosynthesis and the data presented in the chart to determine which of the statements below is a correct explanation for the student's data.

D) Cup 4 had the slowest rate of photosynthesis because it had the least baking soda.

35) P680+ is said to be the strongest biological oxidizing agent. Given its function, why is this necessary?

D) It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has.

51) What compound provides the reducing power for Calvin cycle reactions?

D) NADPH

5) If photosynthesizing green algae are provided with CO2 containing heavy oxygen (18O), later analysis will show that all of the following molecules produced by the algae contain 18O EXCEPT _____.

D) O2

6) Every ecosystem must have _____.

D) autotrophs

42) A flask containing photosynthetic green algae and a control flask containing water with no algae are both placed under a bank of lights, which are set to cycle between 12 hours of light and 12 hours of dark. The dissolved oxygen concentrations in both flasks are monitored. Predict what the relative dissolved oxygen concentrations will be in the flask with algae compared to the control flask. The dissolved oxygen in the flask with algae will _____.

D) be higher in the light, but lower in the dark

33) Carbon dioxide is split to form oxygen gas and carbon compounds _____.

D) in neither photosynthesis nor respiration

2) In autotrophic bacteria, where is chlorophyll located?

D) in the infolded plasma membrane

40) Which process is most directly driven by light energy?

D) removal of electrons from chlorophyll molecules

45) What is the primary function of the Calvin cycle?

D) synthesize simple sugars from carbon dioxide