Biology II – Chapter 7 Self Test
1.
In most land plants, photosynthesis occurs in cells of the ___ of the leaves, because these cells contain the
largest numbers of chloroplasts.
cuticle
Epidermis
Stomata
vascular bundles
Mesophyll
2.
Light energy is initially captured by "photosystems" within thylakoid membranes. Photosystems are organized
arrays of _____.
pigment molecules such as carotenoids
chlorophyll molecules
proteins
all of the above
none of the above
3.
Why is carbon dioxide a key molecule in the light-independent reactions of photosynthesis?
Carbon dioxide is the major product of the light-independent reactions of photosynthesis.
Carbon dioxide provides electrons to replace those lost by chlorophyll during the light-dependent reactions.
Carbon dioxide inhibits the light-independent reactions of photosynthesis.
Carbon dioxide, together with water, is the raw material for the synthesis of sugars, which are the key
products of the light-independent reactions.
4.
What is photorespiration?
Photorespiration is the process by which plants produce energy at night.
Photorespiration is the process by which plant cells cool off in hot climates.
Photorespiration is the process that prevents sugar production in C3 plants when CO2 levels are low and O2
levels are high.
Photorespiration is the process by which plants capture light energy and convert it into ATP.
5.
In the light-dependent reactions of photosynthesis, ATP is produced by chemiosmosis. Describe this process.
When light strikes the chlorophyll molecules, water is moved via osmosis across the chloroplast membrane.
When water moves back across the membrane, ATP is generated.
Chemiosmosis is the process by which water moves across a semipermeable membrane.
As high-energy electrons move from carrier to carrier in the electron transport system of the thylakoid
membrane, some of the energy is captured to pump hydrogen ions across it.
6.
A lovely tree called the flowering plum has beautiful pink flowers in spring and deep-purple leaves in summer.
What types of pigments are plentiful in this plant? Can photosynthesis occur in these purple leaves? Explain your
answer.
The leaves probably contain a high amount of chlorophyll and carotenoids and lesser amounts of
phycocyanins than do plants with green leaves.
The leaves probably contain a high amount of carotenoids and lesser amounts of phycocyanins and
chlorophyll than do plants with green leaves.
The leaves probably contain a high amount of phycocyanins and carotenoids and less chlorophyll than do
plants with green leaves. They can still perform photosynthesis, because photosynthesis can occur to some
extent at all wavelengths of light.
7.
Take a deep breath and slowly exhale. The oxygen in that breath is being used by your mitochondria in reactions
that produce ATP from sugars and other food molecules you ate. Where did that oxygen come from originally?
The oxygen in the atmosphere is produced by the breakdown of carbon dioxide during photosynthesis.
The oxygen in the air is produced by the splitting of water during the light-dependent reactions of
photosynthesis.
Plants produce the oxygen via the process of photorespiration, in which they break down sugars at night
when photosynthesis cannot occur.
Plants produce the oxygen via the process of photorespiration when they break down sugars in their
mitochondria.
8.
A scientist studying photosynthesis illuminated a culture of algae with bright visible light. She then turned out the
light and simultaneously began to bubble radioactive CO2 gas into the culture. After 30 minutes, she stopped the
reaction and measured the amount of radioactivity inside the cells. What did she find? Explain your answer.
There was radioactivity in the cells, because the CO2 is used to synthesize sugar, even in the dark.
There was no radioactivity inside the cells, because the CO2 is used to produce O2 in the light-dependent
reactions. Thus, there was radioactivity in the air above the culture but not in the cells.
There was no radioactivity in the cells, because light is required to produce sugars from CO 2 and water.
There was radioactivity inside the cells, because CO2 is used to replace the electrons that were lost by
chlorophyll when the lights were turned on.
9.
Imagine that you are trying to set up a large fish tank and want to select a colored light that will show off the fish
to best advantage but will also allow the green plants in the tank to grow and stay healthy. You decide to
measure the efficiency of photosynthesis by looking at the production of oxygen bubbles on the leaves (see
Figure 7-5). At first, you use a white fluorescent lamp and see many oxygen bubbles on the leaves, indicating
that photosynthesis is occurring normally. Next, you put a sheet of green cellophane between the white light and
the water so that the light coming through to the tank appears green. Will the oxygen bubbles remain the same,
increase, decrease, or disappear? Explain your answer.
The bubbles will disappear, because photosynthesis cannot occur in green light.
The bubbles will remain constant because photosynthesis can occur to some extent at all visible
wavelengths of light.
The bubbles will increase; because chlorophyll is green, photosynthesis will work best if leaves are exposed
to green light.
The bubbles will decrease, because green light cannot be absorbed by chlorophyll.
10. Which of the following is a true statement about photosynthesis?
In photosynthesis, inorganic molecules such as carbon dioxide and water react to produce organic, energyrich molecules such as glucose.
Photosynthesis is a process that is carried out primarily by autotrophic prokaryotic bacteria.
In photosynthesis, oxygen is used to help break down glucose.
Photosynthesis is an exergonic reaction.
11. Leaves include a number of structural modifications for the purpose of photosynthesis, including __________.
adjustable openings in the surface of the leaf that permit the passage of carbon dioxide, water, and oxygen
a waxy covering on the surface of the leaf that is designed to reduce evaporation
photosynthetic mitochondria
Both the first and second answers are correct.
12. During photosynthesis, electrons are continuously lost from the reaction center of photosystem II. What source is
used to replace these electrons?
sunlight
water
carbon dioxide
oxygen
13. The term carbon fixation refers to __________.
the loss of carbon during glucose synthesis
the incorporation of atmospheric carbon dioxide into a larger organic molecule
the regeneration of ribulose bisphosphate
the synthesis of glyceraldehyde-3-phosphate
14. Photorespiration occurs when __________.
oxygen is combined with ribulose bisphosphate
carbon dioxide is combined with ribulose bisphosphate
stomata are closed
Both the first and third answers are correct.
15. How have C4 plants adapted to environmental conditions that would result in increased photorespiration?
PEP specifically combines with carbon dioxide even in the face of high oxygen concentrations.
C4 plants have substituted phosphoenolpyruvate (PEP) for ribulose bisphosphate.
A molecule transports the fixed carbon into a cell type where the normal C3 synthetic metabolism would be
favored due to the now high concentrations of carbon dioxide.
all of the above
16. The stomata __________.
allow oxygen to exit
allow carbon dioxide to enter
allow light to enter
allow excess heat to exit
The first two answers are correct.
17. You have just discovered a new plant with red-orange leaves. What wavelengths of visible light are NOT being
absorbed by this pigment?
green, blue, and violet
green
green and yellow
red and orange
blue and violet
18. In the light-dependent reactions of photosynthesis the difference in hydrogen ion concentration across the
thylakoid membrane is used to generate __________.
glucose
oxygen
FADH2
NADPH
ATP
19. Which of the following represents the products of the light-dependent reactions of photosynthesis? For what
process are these products needed?
NADPH and glucose; light-independent reactions
carbon dioxide and water; Calvin-Benson cycle
ATP and oxygen; photosystem I
NADPH and ATP; Calvin-Benson cycle
NADH and ADP; cellular respiration
20. Which of the following is NOT required for the light-independent reactions of photosynthesis?
CO2
NADPH
O2
stroma
H2O
ATP
21. _____________________________ converts the energy of sunlight into chemical energy.
22. ____________________________ are organisms that can produce their own food in their cells.
23. Photosynthesis takes place within ____________________________.
24. In the _________________________________, light energy is converted to chemical energy in the form of ATP
and NADPH.
25. In the ___________________________________, chemical energy is used to drive the formation of glucose.
26. _____________________________ is the key light-capturing molecule found in chloroplasts.
27. Complete the following cycle of reactions. For each item below, select the letter that labels the correct part of
the image.
________ - light-dependent reactions (thylakoids)
________ - light-independent reactions (stroma)
________ - ATP, NADPH
________ - ADP, NADP+
28. Using the image below, provide the connections between photosynthesis and cellular respiration. For each item
below, select the letter that labels the correct part of the image.
________ - sugar
________ - O2 (oxygen)
________ - ATP (adenosine triphosphate)
________ - H2O (water)
________ - CO2 (carbon dioxide)
29. Label the structures in this cross section of a leaf. For each item below, select the letter that labels the correct
part of the image.
________ - mesophyll cells
________ - stoma
________ - vascular bundle
________ - cuticle
________ - upper epidermis
________ - chloroplasts
30. Below is a diagram of light-dependent reactions of photosynthesis. Place the descriptions of the steps in this
process next to the appropriate portion of the diagram. For each item below, select the letter that labels the
correct part of the image.
________ - Electrons are passed to the electron transport system.
________ - Light is absorbed by the light-harvesting complex of photosystem II and energy is passed to the
reaction center chlorophyll molecule.
________ - Electrons are ejected out of the energy center.
________ - Due to the action of the electron transport system, a hydrogen gradient is created in thylakoids,
generating ATP.
________ - The electrons from photosystem I are captured in an electron transport system and used to create
NADPH.
________ - Light strikes photosystem I, causing it to emit electrons.
31. Photosynthesis is measured in the leaf of a green plant exposed to different wavelengths of light. Photosynthesis
is
highest in green light
highest in red light
highest in blue light
highest in red and blue light
the same at all wavelengths
32. Where do the light-dependent reactions of photosynthesis occur?
in leaf cell mitochondria
within the thylakoid membranes of the chloroplast
in the stomata
in the leaf cell cytoplasm
in the chloroplast stroma
33. The oxygen produced during photosynthesis comes from
the breakdown of CO2
the breakdown of oxaloacetate
the breakdown of both CO2 and H2O
the breakdown of H2O
photorespiration
34. The role of accessory pigments is to
allow photosynthesis to occur in the dark
prevent photorespiration
donate electrons to chlorophyll reaction centers
provide an additional photosystem to generate more ATP
capture additional light energy and transfer it to the chlorophyll reaction centers
35. The generation of ATP by electron transport in photosynthesis and cellular respiration depends on
a proton gradient across a membrane
proton pumps driven by electron transport chains
an ATP-synthesizing enzyme complex
1, 2, and 3 are all required for ATP generation
none of the above are required for ATP generation
36. Where do the light-independent, carbon-fixing reactions occur?
in the chloroplast stroma
at night in the thylakoids
in the guard cell cytoplasm
within the thylakoid membranes
in mitochondria
KEY
1.
In most land plants, photosynthesis occurs in cells of the __________ of the leaves, because
these cells contain the largest numbers of chloroplasts.
mesophyll
2.
Light energy is initially captured by "photosystems" within thylakoid membranes. Photosystems
are organized arrays of __________.
all of the above
3.
Why is carbon dioxide a key molecule in the light-independent reactions of photosynthesis?
Carbon dioxide, together with water, is the raw material for the
synthesis of sugars, which are the key products of the lightindependent reactions.
4.
What is photorespiration?
Photorespiration is the process that prevents sugar production in C3
plants when CO2 levels are low and O2 levels are high.
5.
In the light-dependent reactions of photosynthesis, ATP is produced by chemiosmosis. Describe
this process.
As high-energy electrons move from carrier to carrier in the electron
transport system of the thylakoid membrane, some of the energy is
captured to pump hydrogen ions across it.
6.
A lovely tree called the flowering plum has beautiful pink flowers in spring and deep-purple leaves
in summer. What types of pigments are plentiful in this plant? Can photosynthesis occur in these
purple leaves? Explain your answer.
The leaves probably contain a high amount of phycocyanins and
carotenoids and less chlorophyll than do plants with green leaves. They
can still perform photosynthesis, because photosynthesis can occur to
some extent at all wavelengths of light.
7.
Take a deep breath and slowly exhale. The oxygen in that breath is being used by your
mitochondria in reactions that produce ATP from sugars and other food molecules you ate. Where
did that oxygen come from originally?
The oxygen in the air is produced by the splitting of water during the
light-dependent reactions of photosynthesis.
8.
A scientist studying photosynthesis illuminated a culture of algae with bright visible light. She then
turned out the light and simultaneously began to bubble radioactive CO2 gas into the culture. After
30 minutes, she stopped the reaction and measured the amount of radioactivity inside the cells.
What did she find? Explain your answer.
There was radioactivity in the cells, because the CO2 is used to
synthesize sugar, even in the dark.
9.
Imagine that you are trying to set up a large fish tank and want to select a colored light that will
show off the fish to best advantage but will also allow the green plants in the tank to grow and
stay healthy. You decide to measure the efficiency of photosynthesis by looking at the production
of oxygen bubbles on the leaves (see Figure 7-5). At first, you use a white fluorescent lamp and
see many oxygen bubbles on the leaves, indicating that photosynthesis is occurring normally.
Next, you put a sheet of green cellophane between the white light and the water so that the light
coming through to the tank appears green. Will the oxygen bubbles remain the same, increase,
decrease, or disappear? Explain your answer.
The bubbles will decrease, because green light cannot be absorbed by
chlorophyll.
10.
Which of the following is a true statement about photosynthesis?
In photosynthesis, inorganic molecules such as carbon dioxide and
water react to produce organic, energy-rich molecules such as
glucose.
11.
Leaves include a number of structural modifications for the purpose of photosynthesis, including
__________.
Both the first and second answers are correct.
12.
During photosynthesis, electrons are continuously lost from the reaction center of photosystem II.
What source is used to replace these electrons?
water
13.
The term carbon fixation refers to __________.
the incorporation of atmospheric carbon dioxide into a larger organic
molecule
14.
Photorespiration occurs when __________.
Both the first and third answers are correct.
15.
How have C4 plants adapted to environmental conditions that would result in increased
photorespiration?
all of the above
16.
The stomata __________.
The first two answers are correct.
17.
You have just discovered a new plant with red-orange leaves. What wavelengths of visible light
are NOT being absorbed by this pigment?
red and orange
18.
In the light-dependent reactions of photosynthesis the difference in hydrogen ion concentration
across the thylakoid membrane is used to generate __________.
ATP
19.
Which of the following represents the products of the light-dependent reactions of photosynthesis?
For what process are these products needed?
NADPH and ATP; Calvin-Benson cycle
20.
Which of the following is NOT required for the light-independent reactions of photosynthesis?
O2
21.
__________ converts the energy of sunlight into chemical energy.
photosynthesis
22.
__________ are organisms that can produce their own food in their cells.
autotrophs
23.
Photosynthesis takes place within __________.
chloroplasts
24.
In the __________, light energy is converted to chemical energy in the form of ATP and NADPH.
light-dependent reactions
25.
In the __________, chemical energy is used to drive the formation of glucose.
light-independent reactions
26.
__________ is the key light-capturing molecule found in chloroplasts.
Chlorophyll
27.
28.
Complete the following cycle of reactions.
light-dependent reactions (thylakoids)
A.
light-independent reactions (stroma)
B.
ATP, NADPH
C.
ADP, NADP+
D.
Using the image below, provide the connections between photosynthesis and cellular respiration.
sugar
D.
O2 (oxygen)
E.
ATP (adenosine triphosphate)
C.
H2O (water)
A.
CO2 (carbon dioxide)
B.
29.
30.
Label the structures in this cross section of a leaf.
mesophyll cells
C.
stoma
F.
vascular bundle
E.
cuticle
A.
upper epidermis
B.
chloroplasts
D.
Below is a diagram of light-dependent reactions of photosynthesis. Place the descriptions of the
steps in this process next to the appropriate portion of the diagram.
Electrons are passed to the electron transport system.
C.
Light is absorbed by the light-harvesting complex of photosystem II and energy
is passed to the reaction center chlorophyll molecule.
A.
Electrons are ejected out of the energy center.
B.
Due to the action of the electron transport system, a hydrogen gradient is
created in thylakoids, generating ATP.
D.
The electrons from photosystem I are captured in an electron transport system
and used to create NADPH.
F.
Light strikes photosystem I, causing it to emit electrons.
31.
E.
Photosynthesis is measured in the leaf of a green plant exposed to different wavelengths of light.
Photosynthesis is
highest in red and blue light
32.
Where do the light-dependent reactions of photosynthesis occur?
within the thylakoid membranes of the chloroplast
33.
The oxygen produced during photosynthesis comes from
the breakdown of H2O
34.
The role of accessory pigments is to
capture additional light energy and transfer it to the chlorophyll reaction
centers
35.
The generation of ATP by electron transport in photosynthesis and cellular respiration depends on
1, 2, and 3 are all required for ATP generation
36.
Where do the light-independent, carbon-fixing reactions occur?
in the chloroplast stroma