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1. Figure 5.7 On a hot, dry day, plants close their stomata to conserve water.
What impact will this have on photosynthesis?
- Levels of carbon dioxide (a reactant) will fall, and levels of oxygen (a product) will rise.
- As a result, the rate of photosynthesis will slow down.
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2. What two products result from photosynthesis?
water and carbon dioxide
Water and oxygen
glucose and oxygen
glucose and carbon dioxide
glucose and oxygen
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3. Which statement about thylakoids in eukaryotes is not correct?
Thylakoids are assembled into stacks.
Thylakoids exist as a maze of folded membranes.
The space surrounding thylakoids is called stroma.
Thylakoids contain chlorophyll.
Thylakoids exist as a maze of folded membranes.
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4. From where does a heterotroph directly obtain its energy?
the sun
the sun and eating other organisms
eating other organisms
simple chemicals in the environment
eating other organisms
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5. What is the energy of a photon first used to do in photosynthesis?
split a water molecule
energize an electron
produce ATP
synthesize glucose
energize an electron
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6. Which molecule absorbs the energy of a photon in photosynthesis?
ATP
glucose
chlorophyll
water
chlorophyll
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7. Plants produce oxygen when they
photosynthesize. Where does the oxygen come from?
splitting water molecules
ATP synthesis
the electron transport chain
chlorophyll
splitting water molecules
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8. Which color(s) of light does chlorophyll a reflect?
red and blue
green
red
blue
green
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9. Where in plant cells does the Calvin cycle take place?
thylakoid membrane
thylakoid space
stroma
granum
stroma
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10. Which statement correctly describes carbon
fixation?
the conversion of CO 2 to an organic compound
the use of RUBISCO to form 3-PGA
the production of carbohydrate molecules from G3P
the formation of RuBP from G3P molecules
the use of ATP and NADPH to reduce CO 2
the conversion of CO 2 to an organic compound
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11. What is the molecule that leaves the Calvin cycle to be converted into glucose?
ADP
G3P
RuBP
3-PGA
G3P
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12. What is the overall purpose of the light reactions in photosynthesis?
To convert solar energy into chemical energy that cells can use to do work.
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13. Why are carnivores, such as lions, dependent on photosynthesis to survive?
Because lions eat animals that eat plants.
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14. Describe the pathway of energy in light-dependent reactions.
- A photon of light hits chlorophyll, causing an electron to be energized.
- The free electron travels through the electron transport chain, and the energy of the electron is
- used to pump hydrogen ions into the thylakoid space, transferring the energy into the electrochemical gradient.
- The energy of the electrochemical gradient is used to power ATP synthase, and the energy is transferred into
- a bond in the ATP molecule. In addition, energy from another photon can be used to create a high-energy bond in the molecule NADPH.
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15. Which part of the Calvin cycle would be affected if a cell could not produce the enzyme RuBisCO?
- None of the cycle could take place, because RuBisCO is essential in fixing carbon dioxide.
- Specifically, RuBisCO catalyzes the reaction between carbon dioxide and RuBP at the start of the cycle.
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16. Explain the reciprocal nature of the net chemical reactions for photosynthesis and respiration.
- Photosynthesis takes the energy of sunlight and combines water and carbon dioxide to produce sugar and oxygen as a waste product.
- The reactions of respiration take sugar and consume oxygen to break it down into carbon dioxide and water, releasing energy.
- Thus, the reactants of photosynthesis are the products of respiration, and vice versa.
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