Campbell Biology

Lisa A. Urry

Chapter 10

Photosynthesis - all with Video Answers

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Chapter Questions

Problem 1

The light reactions supply the Calvin cycle with
(A) light energy.
(C) $\mathrm{H}_{2} \mathrm{O}$ and NADPH.
(B) $\mathrm{CO}_{2}$ and ATP.
(D) ATP and NADPH.

Leah Lampen

Leah Lampen

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Problem 2

Which of the following sequences correctly represents the flow of electrons during photosynthesis?
(A) NADPH $\rightarrow \mathrm{O}_{2} \rightarrow \mathrm{CO}_{2}$
(B) $\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{NADPH} \rightarrow$ Calvin cycle
(C) $\mathrm{H}_{2} \mathrm{O} \rightarrow$ photosystem $\mathrm{I} \rightarrow$ photosystem II
(D) NADPH $\rightarrow$ electron transport chain $\rightarrow \mathrm{O}_{2}$

Haig Manoukian

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Problem 3

How is photosynthesis similar in $\mathrm{C}_{4}$ plants and CAM plants?
(A) In both cases, only photosystem 1 is used.
(B) Both types of plants make sugar without the Calvin cycle.
(C) In both cases, rubisco is not used to fix carbon initially.
(D) Both types of plants make most of their sugar in the dark.

Leah Lampen

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Problem 4

Which of the following statements is a correct distinction between autotrophs and heterotrophs?
(A) Autotrophs, but not heterotrophs, can nourish themselves beginning with $\mathrm{CO}_{2}$ and other nutrients that are inorganic.
(B) Only heterotrophs require chemical compounds from the environment.
(C) Cellular respiration is unique to heterotrophs.
(D) Only heterotrophs have mitochondria.

Dominador Tan

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Problem 5

Which of the following occurs during the Calvin cycle?
(A) carbon fixation
(B) reduction of NADP
(C) release of oxygen
(D) generation of $\mathrm{CO}_{2}$

Leah Lampen

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Problem 6

In mechanism, photophosphorylation is most similar to
(A) substrate-level phosphorylation in glycolysis.
(B) oxidative phosphorylation in cellular respiration.
(C) carbon fixation.
(D) reduction of NADP"

Leah Lampen

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Problem 7

Which process is most directly driven by light energy?
(A) creation of a pH gradient by pumping protons across the thylakoid membrane
(B) reduction of NADP' molecules
(C) transfer of energy from pigment molecule to pigment molecule
(D) ATP synthesis

Leah Lampen

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Problem 8

Scientific evidence indicates that the $\mathrm{CO}_{2}$ added to the air by the burning of wood and fossil fuels is contributing to global warming, a rise in global temperature. Tropical rain forests are estimated to be responsible for approximately $20 \%$ of global photosynthesis, yet the consumption of large amounts of $\mathrm{CO}_{2}$ by living trees is thought to make little or no net contribution to reduction of global warming. Explain why this might be the case. (Hint:
What processes in both living and dead trees produce $\mathrm{CO}_{2} ?$ )

Leah Lampen

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Problem 9

Photorespiration can decrease soybeans" photosynthetic output by about $50 \%$. Would this figure be higher or lower in wild relatives of soybeans? Why?

Leah Lampen

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Problem 10

The following diagram represents an experiment with isolated thylakoids. The thylakoids were first made acidic by soaking them in a solution at pH 4 . After the thylakoid space reached $\mathrm{pH} 4$, the thylakoids were transferred to a basic solution at $\mathrm{pH}$. The thylakoids then made ATP in the dark. Draw an enlargement of part of the thylakoid membrane in the beaker with the solution at $\mathrm{pH}$. . Draw ATP synthase. Label the areas of high $\mathrm{H}^{+}$ concentration and low $\mathrm{H}^{+}$ concentration. Show the direction protons flow through the enzyme, and show the reaction where ATP is synthesized. Would ATP end up in the thylakoid or outside of it? Explain why the thylakoids in the experiment were able to make ATP in the dark.

Leah Lampen

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Problem 11

In a short essay ( $100-150$ words), describe how photosynthesis transforms solar energy into the chemical energy of sugar molecules.

Leah Lampen

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Problem 12

"Watermelon snow" in Antarctica is caused by a certain species of photosynthetic green algae that thrives in subzero temperatures (Chlamydomonas nivalis). These algae are also found in high-altitude, year-round snowfields. In both locations, UV light levels tend to be high. Propose an explanation for why this alga appears reddish-pink.

Leah Lampen

Numerade Educator