Deck 10: Photosynthesis

Question 1

The absorption spectrum of a plant shows what wavelengths of light the plant absorbs. The absorption spectrum depends on

A) wavelengths of light to which the plant's pigments respond.
B) the thickness of the plant's leaves.
C) wavelengths of light that are transmitted by the plant.
D) the wavelengths of light that hit the plant.

Answer 1

A

Question 2

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

A) A carboxylation reaction of the Calvin cycle occurs.
B) Electrons are stripped from NADPH.
C) An electron is excited.
D) ATP is synthesized from the energy absorbed.

Answer 2

C

Question 3

Energy from sunlight can excite electrons, kicking them out of their orbitals and creating free radicals. Free radicals are highly reactive atoms or molecules that have unpaired electrons. They degrade and destroy other compounds in their vicinity. Carotenoids, one of the pigments present in most chloroplasts, can stabilize these free radicals. This suggests that

A) carotenoids probably have a protective function in the cell.
B) once chloroplasts are destroyed, the free radicals will destroy the cell.
C) other pigments besides carotenoids and chlorophyll) are essential for the health of a plant cell.
D) carotenoids communicate directly with the immune system of plants.

Answer 3

A

Question 4

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

A) The single band of pigment that is isolated is always some shade of green.
B) Paper chromatography would separate the pigments from a particular plant into several bands.
C) Paper chromatography isolates only the pigments that reflect green light.
D) Paper chromatography for the plant would isolate a single band of pigment that is characteristic of the particular plant.

Question 5

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

A) Photosynthesis occurs only in plants; respiration occurs only in animals.
B) Respiration runs the biochemical pathways of photosynthesis in reverse.
C) ATP molecules are produced in photosynthesis but not in aerobic respiration.
D) Photosynthesis is catabolic; respiration is anabolic.
E) Photosynthesis stores energy in complex organic molecules; respiration releases energy from complex organic molecules.

Question 6

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

A) It is lost as heat.
B) It excites electrons of the reaction center of photosystem I.
C) It is used to establish and maintain a proton gradient.
D) It is used to phosphorylate NAD⁺ to NADPH, the molecule that accepts electrons from photosystem I.

Question 7

What is the difference between NAD⁺ and NADP⁺?

A) Both transport electrons to the electron transport chain ETC) found on the inner mitochondrial membrane, but NADP⁺ transfers its electrons to the ETC at a higher energy level.
B) Both function as electron carriers, but NADP⁺ has a phosphate group and NAD⁺ does not.
C) NAD⁺ functions as a free energy source for cells, whereas NADP⁺ does not.
D) NAD⁺ functions as an electron transporter, whereas NADP⁺ does not.

Question 8

Besides proteins, thylakoid membranes must contain a large number of molecules in the reaction centers in order to harvest light energy.

A) pigment
B) electron carrier
C) oligosaccharide
D) phospholipid

Question 9

What is a difference between chlorophyll a and chlorophyll b?

A) Chlorophyll a is a pigment, and chlorophyll b is the enzyme that transfers excited electrons from chlorophyll a to electron carriers of the thylakoid membrane.
B) Chlorophyll a and b absorb light energy at slightly different wavelengths.
C) Chlorophyll a absorbs yellow light, and chlorophyll b absorbs green.
D) Chlorophyll a contains Mg⁺⁺ in a ring structure, whereas chlorophyll b contains iron.

Question 10

Based on what you know about the structure and function of the antenna complex, irradiating a leaf with which of the following light types would result in the release of the greatest quantities of oxygen?

A) red and blue light
B) blue and orange light
C) green and blue light
D) red and orange light

Question 11

The proteins of the electron transport chain active in the light- dependent reactions

A) are free proteins present in the thylakoid lumen.
B) have hydrophilic exterior surfaces.
C) are part of the reaction center of photosystem I.
D) are membrane proteins present in the thylakoid.

Question 12

Which of the following statements concerning chloroplasts is FALSE?

A) They have an internal membrane system known as the thylakoids.
B) They have outer and inner membranes.
C) They are unrelated to plastids.
D) They have their own DNA.

Question 13

The process of photosynthesis probably originated

A) in plants.
B) three separate times.
C) in fungi.
D) in prokaryotes.

Question 14

In autumn, the leaves of deciduous trees change colours. This is because the chlorophyll is degraded, and

A) the carotenoids and other pigments are still present in the leaves.
B) water supply to the leaves has been reduced.
C) degraded chlorophyll becomes a pigment with different colours.
D) the cells of the leaves begin to die.

Question 15

Chlorophylls absorb light in which colours of the visible range?

A) blue and red
B) orange and blue
C) green and red
D) green and blue

Question 16

Which of the following is FALSE regarding photosynthesis?

A) The earliest form of photosynthetic reactions oxidized used) H₂O and yielded O₂.
B) Development of oxygenic photosynthesis led to atmospheric changes that allowed evolution of cells/organisms able to use aerobic respiration.
C) Some forms of photosynthesis involve oxidizing compounds such as ferrous iron or H₂S.
D) It first appeared in ancient prokaryotes.

Question 17

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) They enable the reaction center to excite electrons to a higher energy level.
D) This setup enables the plant to absorb energy from sunlight from a variety of wavelengths.

Question 18

Plastoquinone PQ), an electron carrier of small molecular weight, is found in the electron transport chain associated with photosystem II. If PQ is not directly anchored to other membrane or cytoplasmic structures, it is probably

A) mobile in the thylakoid membrane.
B) lipid soluble.
C) a molecule that serves as a shuttle between the electron transport chain and ATP synthase.
D) both A and B.

Question 19

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

A) H₂S.
B) glucose.
C) water.
D) electrons from NADPH.

Question 20

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

A) Bright sunlight destroys photosynthetic pigments.
B) Aerobic bacteria take up oxygen, which changes the measurement of the rate of photosynthesis.
C) Green and yellow wavelengths inhibit the absorption of red and blue wavelengths.
D) Other pigments absorb light in addition to chlorophyll a.
E) Oxygen given off during photosynthesis interferes with the absorption of light.

Question 21

In the carbon fixation step of the Calvin cycle, ribulose- 1,5- bisphosphate a five- carbon compound) is carboxylated to produce

A) glucose.
B) acetyl CoA two carbons) and oxaloacetate four carbons).
C) citric acid.
D) 2 three- carbon compounds.

Question 22

How does carbon fixation differ between C₃ and C₄ plants?

A) C₄ plants undergo carbon fixation by carboxylation of a four- carbon substrate oxaloacetate), while in C₃ plants, a three- carbon compound phosphoglycerate) is carboxylated.
B) C₃ plants don't undergo photorespiration, but C₄ plants do.
C) Both C₃ and C₄ plants involve carboxylation of ribulose- 1,5- bisphosphate by rubisco; but in C₃, the first stable intermediate is 3- phosphoglycerate, and in C₄, it is oxaloacetate.
D) Rubisco is the primary enzyme that catalyzes carbon fixation in C₃ plants, and phosphoenolpyruvate carboxylase can catalyze carbon fixation in C₄ plants.

Question 23

Most of the enzymes of the Calvin cycle also function in other metabolic pathways. This should not be a surprising finding, because

A) the Calvin cycle probably evolved at the same time as did glycolysis.
B) the Calvin cycle is nearly ubiquitous in cells, as are metabolic pathways.
C) metabolic reactions are catalyzed by enzymes that have multiple functions.
D) there is a close relationship between carbohydrate synthesis and metabolic breakdown.

Question 24

The final electron acceptors) associated with photosystem I is

A) NADP⁺.
B) hydrogen ions.
C) pheophytin.
D) oxygen.

Question 25

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) the electron carrier, plastocyanin
B) photosystem I
C) oxygen
D) water

Question 26

Melvin Calvin introduced radiolabeled carbon dioxide into plants. Which of the following molecules should he have expected to see radiolabeled first?

A) glutamate
B) succinate
C) oxaloacetate
D) 3- phosphoglycerate

Question 27

Photorespiration is

A) not a problem, because oxygen is not available in the chloroplast where photorespiration takes place.
B) a process involving the carboxylation of ribulose- 1,5- bisphosphate.
C) a process involving addition of oxygen to ribulose- 1,5- bisphosphate and the formation of ribose- 1,5- diphosphate.
D) a process involving the addition of oxygen to ribulose- 1,5- bisphosphate and the formation of the products 3- phosphoglycerate and 2- phosphoglycolate.

Question 28

Stomata, openings in the leaf, are important to photosynthesis for

A) entry of oxygen that is used in the Calvin cycle.
B) removal of water and carbon dioxide, the end- products of photo- oxidation.
C) entry of carbon dioxide that is used in the Calvin cycle.
D) removal of nitrogen- containing waste products.

Question 29

During a discussion of photosynthesis, you are given the following series of facts:
1) Photosystem P700 alone is involved.
2) Water- splitting is not occurring.
3) A proton gradient is created in the Thylakoid lumen.
To which of the following processes do these statements collectively refer?

A) the Krebs cycle Citric Acid Cycle)
B) the Calvin cycle
C) linear electron transport
D) cyclic electron transport

Question 30

The light- independent reactions of plants function to make organic molecules using carbon dioxide as a carbon source. What is the electron source that helps reduce carbon dioxide to sugars and other organic molecules?

A) electrons from oxygen
B) ATP
C) NADPH
D) NADH

Question 31

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

A) test for CO₂ fixation in the dark.
B) determine whether they have thylakoids in the chloroplasts.
C) do experiments to generate an action spectrum.
D) test for liberation of O₂ in the light.
E) test for production of either sucrose or starch.

Question 32

In the light dependent reactions of photosynthesis, the plant cell will conduct both linear and cyclic electron transport. This is needed because

A) electrons are accepted by ferrodoxin during electron transport and without this, ATP synthesis would not occur.
B) linear electron transport processes do not absorb enough light to allow for the synthesis of ATP.
C) more NADPH is needed compared to ATP in the subsequent light independent reactions Calvin cycle).
D) more ATP is needed compared to NADPH in the subsequent light independent reactions Calvin cycle).

Question 33

Both C₃ and C₄ plants have the enzymes of the Calvin cycle. How are C₄ plants more efficient than C₃ plants at fixing carbon?

A) C₄ plants fix carbon using the Calvin cycle; C₃ plants use the reverse of glycolysis, a series of reactions that requires more energy in the form of ATP.
B) In C₄ plants, carbon fixation takes place in mesophyll cells, whereas the Calvin cycle takes place in bundle- sheath cells.
C) Both the carbon fixation reaction and the Calvin cycle take place in mesophyll cells, but the carbon fixation reactions take place in the dark, and the Calvin cycle is light dependent.
D) C₄ plants do not have rubisco and therefore do not undergo photorespiration.

Question 34

Purple photosynthetic bacteria do not contain chloroplasts. They have an antenna system that includes two light- harvesting protein complexes, both of which are integral membrane proteins. The bacteriochlorophyll a molecules contain Mg²⁺ and absorb light at 800 nm. Which of the following statements comparing photosynthesis in purple bacteria and plant chloroplasts is true?

A) Because purple bacteria do not have chloroplasts, there is no electron transport associated with photosynthesis.
B) Plant chlorophyll a absorbs in the visible light range, whereas purple photosynthetic bacteriochlorophyll a absorbs light at a longer wavelength.
C) Bacteriochlorophyll a absorbs light most efficiently in the ultraviolet range, at a significantly shorter wavelength than that for chlorophyll a of chloroplasts.
D) Bacteriochlorophyll a is a molecule containing Mg²⁺, whereas chlorophyll a from chloroplasts contains Fe²⁺.

Question 35

Data suggest that rubisco ribulose- 1,5- bisphosphate carboxylase) makes up 10% of the total protein found in spinach leaves. Research elucidating the structure of rubisco shows that it has four active sites. Why, with four active sites, might there be such a large concentration of rubisco in plant matter?

A) Rubisco is a very slow enzyme; what it lacks in speed, it makes up in numbers.
B) Rubisco catalyzes four of the six reactions found in the Calvin cycle.
C) Three of the four active sites bind carbon dioxide; only one binds ribulose- 1,5- bisphosphate.
D) All heterotrophic organisms depend on plants, either directly or indirectly, for their food supply.

Question 36

How are the light- dependent and light- independent reactions of photosynthesis related?

A) The products of light- independent reactions must be present for light- dependent reactions to take place.
B) They cannot occur in the absence of light.
C) The products of light- dependent reactions are used in light- independent reactions.
D) They are not related.

Question 37

In photosynthesis, what is the role of water H₂O)?

A) It accepts electrons liberated from the reaction centre of photosystem I.
B) It provides O2, the terminal electron acceptor for the electron transport chain.
C) It allows cyclic photophosphorylation to occur when ATP levels are low in the stroma.
D) It donates electrons to replace lost electrons in the reaction centre of photosystem II.
E) It provides the necessary H+ ions needed to reduce glyceraldehyde- 3- phosphate G3P).

Question 38

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

A) H₂O -NADPH - Calvin cycle
B) NADPH - O₂ -CO₂
C) NADPH -chlorophyll -Calvin cycle
D) NADPH -electron transport chain - O₂
E) H₂O -photosystem I -photosystem II

Question 39

Which of the following procedures would identify the enzyme that catalyzes the carboxylation of ribulose- 1,5- bisphosphate?

A) differential sedimentation of a protein extract
B) introducing radiolabeled carbon dioxide into a plant extract and determining which molecules become radiolabeled
C) irradiating a leaf extract with red light
D) purifying a variety of proteins from plant extracts and testing each protein individually to see if it can carboxylate ribulose- 1,5- bisphosphate

Question 40

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

A) splitting of water.
B) reduction of NADP⁺_.
C) synthesis of ATP.
D) absorption of light energy by chlorophyll.
E) flow of electrons from photosystem II to photosystem I.

Question 41

Photorespiration

A) generates carbon dioxide and consumes ATP and oxygen.
B) generates ATP and sugars and consumes oxygen and carbon dioxide.
C) generates oxygen and ATP, and consumes sugars and carbon dioxide.
D) generates oxygen and consumes ATP, carbon dioxide, and sugars.
E) consumes carbon dioxide and generates ATP, sugars, and oxygen.