Lesson 2: Photosynthesis

Question 1

The reactions that produce molecular oxygen (O) take place in

A. neither the light reactions nor the Calvin cycle.
B. the Calvin cycle alone.
C. the chloroplast, but are not part of photosynthesis.
D. the light reactions alone.
E. both the light reactions and the Calvin cycle.

Answer 1

D. the light reactions alone.

Question 2

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, Pi, and NADP+
C. CO2 and glucose
D. ATP and NADPH
E. H2O and O2

Answer 2

D. ATP and NADPH

Question 3

Where does the Calvin cycle take place?

A. the interior of the thylakoid (thylakoid space)
B. stroma of the chloroplast
C. thylakoid membrane
D. cytoplasm surrounding the chloroplast
E. the outer membrane of the chloroplast

Answer 3

B. stroma of the chloroplast

Question 4

Which of the events listed below occurs in the light reactions of photosynthesis?

A. NADP is produced.
B. Light is absorbed and funnelled to reaction-centre
chlorophyll a.
C. NADPH is reduced to NADP+.
D. Carbon dioxide is incorporated into PGA.
E. ATP is phosphorylated to yield ADP.

Answer 4

B. Light is absorbed and funnelled to reaction-centre chlorophyll a.

Question 5

It is a particularly hot, dry summer. The town has banned excessive water use and so you cannot water your lawn. After a few weeks, the grass has gone brown, except a few patches where the grass seems to be doing fine. You notice that this grass has a broader leaf and is not the same species as most of your lawn. You conclude that this grass is a

A. C4 plant.
B. C3 plant.
C. a mutant.
D. C5 plant.
E. CAM plant.

Answer 5

A. C4 plant.

Question 6

Where is the Calvin cycle located in a C4 plant?

A. bundle sheath cells
B. mesophyll cells
C. stomata
D. stems
E. the chloroplasts in leaves

Answer 6

A. bundle sheath cells

Question 7

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

A. They are separate phenomena.
B. They are logarithmically related.
C. They are inversely related.
D. They have a direct, linear relationship.
E. They are only related in certain parts of the spectrum.

Answer 7

C. They are inversely related.

Question 8

In thylakoids, protons travel through ATP synthase from the thylakoid space to the stroma. Therefore, the catalytic “knobs” of ATP synthase would be located

A. built into the centre of the thylakoid stack (granum).
B. on the side facing the thylakoid space.
C. on the ATP molecules themselves.
D. on the stromal side of the membrane.
E. on the pigment molecules of photosystem I and
photosystem II.

Answer 8

D. on the stromal side of the membrane.

Question 9

Photosynthesis is not responsible for

A. fossil fuels.
B. atmospheric CO2.
C. the ozone layer.
D. most of the organic carbon on Earth's surface.
E. oxygen in the atmosphere.

Answer 9

B. atmospheric CO2.

Question 10

CO2 + H2O → [CH2O] + O2 represents the simplified equation for

A. respiration.
B. chemiosmosis.
C. photosynthesis.
D. photophosphorylation.
E. chemosynthesis.

Answer 10

C. photosynthesis.

Question 11

Which of the following are directly associated with photosystem I?

A. extraction of hydrogen electrons from the splitting of
water
B. receiving electrons from the thylakoid membrane
electron transport chain
C. harvesting of light energy by ATP
D. passing electrons to the thylakoid membrane
electron transport chain
E. generation of molecular oxygen

Answer 11

B. receiving electrons from the thylakoid membrane electron transport chain

Question 12

Reactions that require CO2 take place in

A. the Calvin cycle alone.
B. the light reactions alone.
C. both the light reactions and the Calvin cycle.
D. the chloroplast, but are not part of photosynthesis.
E. neither the light reactions nor the Calvin cycle.

Answer 12

A. the Calvin cycle alone.

Question 13

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

A. Less oxygen would be produced.
B. Photosynthetic efficiency would be reduced at low
light intensities.
C. Cells would carry on the Calvin cycle at a much
slower rate.
D. Less ATP would be generated.
E. There would be more light-induced damage to the
cells.

Answer 13

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

Question 14

In C3 photosynthesis, the reactions that require ATP take place in

A. the light reactions alone.
B. the Calvin cycle alone.
C. the chloroplast, but are not part of photosynthesis.
D. neither the light reactions nor the Calvin cycle.
E. both the light reactions and the Calvin cycle.

Answer 14

B. the Calvin cycle alone.

Question 15

When pigments in an excited state relax back to ground state, they

A. release energy as fluorescence and heat.
B. lose an electron.
C. release energy as fluorescence.
D. absorb photons.
E. release energy as heat.

Answer 15

A. release energy as fluorescence and heat.

Question 16

According to the endosymbiotic theory, the original chloroplast was a

A. chemosynthetic archaea.
B. purple sulphur bacteria.
C. green algae.
D. photosynthetic prokaryote.
E. mitochondria.

Answer 16

D. photosynthetic prokaryote.

Question 17

Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?

A. The light reactions provide ATP and NADPH to the
carbon fixation step of the Calvin cycle, and the
cycle provides water and electrons to the light
reactions.
B. The light reactions provide ATP and NADPH to the
Calvin cycle and the cycle returns ADP, Pi, and
NADP+ to the light reactions.
C. The light reactions supply the Calvin cycle with CO2
to produce sugars, and the Calvin cycle supplies the
light reactions with sugars to produce ATP.
D. There is no relationship between the light reactions
and the Calvin cycle.
E. The light reactions provide the Calvin cycle with
oxygen for electron flow, and the Calvin cycle
provides the light reactions with water to split.

Answer 17

B. The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, Pi, and NADP+ to the light reactions.

Question 18

If the process of photosynthesis had never evolved on Earth, this planet would

A. have no land and be primarily ocean.
B. have no water and be dry land.
C. be very similar to the way it is today.
D. have no oxygen and thus no life.
E. only contain anaerobic organisms.

Answer 18

E. only contain anaerobic organisms.

Question 19

Compared to C3 plants, C4 plants

A. grow better under cool, moist conditions.
B. do not use rubisco for carbon fixation.
C. have higher rates of photorespiration.
D. make a four-carbon compound, oxaloacetate, which
is then delivered to the citric acid cycle in
mitochondria.
E. can continue to fix CO2 even at relatively low CO2
concentrations and high oxygen concentrations.

Answer 19

E. can continue to fix CO2 even at relatively low CO2 concentrations and high oxygen concentrations.

Question 20

Three “turns” of the Calvin cycle generate a “surplus” molecule of glyceraldehyde 3-phosphate (G3P). Which of the following is a consequence of this?

A. Some plants would not taste sweet to us.
B. Formation of a molecule of glucose would require
nine “turns.”
C. Plants accumulate and store G3P.
D. G3P more readily forms sucrose and other
disaccharides than it does monosaccharides.
E. The formation of sucrose and starch in plants
involves assembling G3P molecules, with or without
further rearrangements.

Answer 20

E. The formation of sucrose and starch in plants involves assembling G3P molecules, with or without further rearrangements.

Question 21

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

A. They use PEP carboxylase to initially fix CO2.
B. They are adapted to cold, wet climates.
C. They exclude oxygen from their tissues.
D. They conserve water more efficiently.
E. They do not participate in the Calvin cycle.

Answer 21

A. They use PEP carboxylase to initially fix CO2.

Question 22

Plants photosynthesize only in the light. Plants respire

A. only when excessive light energy induces photorespiration.
B. in the light only.
C. never–they get their ATP from photophosphorylation.
D. in the dark only.
E. both in light and dark.

Answer 22

E. both in light and dark.

Question 23

A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are being absorbed by this pigment?

A. green and yellow
B. red and yellow
C. green, blue, and yellow
D. blue, green, and red
E. blue and violet

Answer 23

E. blue and violet

Question 24

Halobacterium has a photosynthetic membrane that is coloured purple. Its photosynthetic action spectrum is exactly complementary (opposite to) the action spectrum for green plants. What wavelengths of light do the Halobacterium photosynthetic pigments absorb?

A. red and yellow
B. blue and red
C. green and yellow
D. red and green
E. blue, green, and red

Answer 24

B. blue and red

Question 25

Photorespiration occurs when rubisco reacts RuBP with

A. O2.
B. glyceraldehyde 3-phosphate.
C. 3-phosphoglycerate.
D. CO2.
E. NADPH.

Answer 25

A. O2.

Question 26

When oxygen is released as a result of photosynthesis, it is a direct by-product of

A. reducing NADP+.
B. splitting water molecules.
C. the electron transfer system of photosystem II.
D. chemiosmosis.
E. the electron transfer system of photosystem I.

Answer 26

B. splitting water molecules.

Question 27

What is the primary function of the Calvin cycle?

A. use NADPH to release carbon dioxide
B. synthesize simple sugars from carbon dioxide
C. split water and release oxygen
D. use ATP to release carbon dioxide
E. transport RuBP out of the chloroplast

Answer 27

B. synthesize simple sugars from carbon dioxide

Question 28

Use the following information to answer the questions below.

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. What wavelengths of light should be used to maximize plant growth with a minimum of energy expenditure?

A. a mixture of blue and red light
B. UV light
C. full-spectrum white light
D. green light
E. yellow light

Answer 28

A. a mixture of blue and red light

Question 29

A gardener is concerned that her greenhouse is getting too hot from too much light, and seeks to shade her plants with coloured translucent plastic sheets. What colour should she use to reduce overall light energy, but still maximize plant growth?

A. blue
B. green
C. yellow
D. orange
E. Any colour will work equally well.

Answer 29

A. blue

Question 30

Which statement describes the functioning of photosystem II?

A. The P680 chlorophyll donates a pair of protons to
NADP+, which is thus converted to NADPH.
B. The splitting of water yields molecular carbon
dioxide as a by-product.
C. The electron vacancies in P680+ are filled by
electrons derived from water.
D. Photons are passed along to a reaction-centre
chlorophyll.
E. Light energy excites electrons in the thylakoid
membrane electron transport chain.

Answer 30

C. The electron vacancies in P680+ are filled by electrons derived from water.

Question 31

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

A. Each one minimizes both water loss and the rate of
photosynthesis.
B. CAM plants allow more water loss, while C4 plants
allow less CO2 into the plant.
C. C4 compromises on water loss and CAM
compromises on photorespiration.
D. C4 plants allow less water loss but CAM plants allow
more water loss.
E. Both minimize photorespiration but expend more
ATP during carbon fixation.

Answer 31

E. Both minimize photorespiration but expend more ATP during carbon fixation.