Biology Exam 3

For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle.

2

Chloroplast membrane vesicles are equilibrated in a simple solution of pH 5‎ . The solution is then adjusted to pH 8‎ . Which of the following conclusions can be drawn from these experimental conditions?

ATP will not be produced because there is no ADP and inorganic phosphate in the solution.

How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.)

Both electron transport and ATP synthesis would stop.

The parent cell that enters meiosis is diploid, whereas the four daughter cells that result are haploid. Which statement correctly describes how cellular DNA content and ploidy levels change during meiosis I and meiosis II?

DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II.

In the oxidation of pyruvate to acetyl CoA, one carbon atom is released as CO2. However, the oxidation of the remaining two carbon atoms—in acetate—to CO2 requires a complex, eight-step pathway—the citric acid cycle. Consider four possible explanations for why the last two carbons in acetate are converted to CO2 in a complex cyclic pathway rather than through a simple, linear reaction.

It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA.

Why is it correct to say that the linear electron flow of the light reactions directly captures energy in NADPH but only indirectly captures energy in ATP?

Electrons are directly transferred to NADP+ to form NADPH, but electron flow is used to generate a proton gradient for ATP synthesis. Electrons are not directly transferred to ATP.

During electron transport, energy from _____ is used to pump hydrogen ions into the _____.

NADH and FADH2 ... intermembrane space

After 3-PGA is phosphorylated, it is reduced by _____.

NADPH

In C4 and CAM plants carbon dioxide is fixed in the _____ of mesophyll cells.

cytoplasm

The proximate (immediate) source of energy for oxidative phosphorylation is _____.

kinetic energy that is released as hydrogen ions diffuse down their concentration gradient

In cellular respiration, most ATP molecules are produced by _____.

oxidative phosphorylation

The final electron acceptor of cellular respiration is _____.

oxygen

In C3 plants the conservation of water promotes _____.

photorespiration

In the citric acid cycle, ATP molecules are produced by _____.

substrate-level phosphorylation

In mitochondrial electron transport, what is the direct role of O2?

to function as the final electron acceptor in the electron transport chain

C4 plants differ from C3 and CAM plants in that C4 plants _____.

transfer fixed carbon dioxide to cells in which the Calvin cycle occurs

Cytokinesis in animal cells is accomplished by constriction of the cell along the plane of cell division (formation of a cleavage furrow). In plant cells, which have cell walls, a completely different mechanism of cytokinesis has evolved.

-The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells. -Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate.

How many electrons at a time are passed between the pigment molecules in the light-harvesting complexes?

0

Drag the terms on the left to correctly complete these sentences. Not all the terms will be used.

1. DNA replication produces two identical DNA molecules, called sister chromatid(s), which separate during mitosis. 2. After chromosomes condense, the centromere(s) is the region where the identical DNA molecules are most tightly attached to each other. 3. During mitosis, microtubules attach to chromosomes at the kinetochore(s). 4. In dividing cells, most of the cell's growth occurs during interphase. 5. The mitotic spindle(s) is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division. 6. During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called chromatin. 7. In most eukaryotes, division of the nucleus is followed by cytokinesis, when the rest of the cell divides. 8. The centrosome(s) are the organizing centers for microtubules involved in separating chromosomes during mitosis.

Complete the sentences by dragging the terms to the appropriate locations. Terms may be used once, more than once, or not at all.

1. During prophase, the microtubules of the mitotic spindle lengthen. 2. During anaphase, the nonkinetochore microtubules lengthen and move past each other, and the kinetochore microtubules shorten. 3. During telophase, the nonkinetochore microtubules disassemble.

Drag the terms to the appropriate blanks to complete the following sentences summarizing the redox reactions of photosynthesis. Terms may be used once, more than once, or not at all.

1. In the light reactions, light energy is used to oxidize H2O to O2. 2. The electrons derived from this oxidation reaction in the light reactions are used to reduce NADP+ to NADPH. 3. The Calvin cycle oxidizes the light-reactions product NADPH to NADP+. 4. The electrons derived from this oxidation reaction in the Calvin cycle are used to reduce CO2 to G3P.

Consider three questions concerning the animal cell that has been treated with the inhibitor. Drag the terms to answer the questions. Terms may be used once, more than once, or not at all.

1. Will this cell elongate during mitosis? yes 2. Will the sister chromatids separate from each other? yes 3. Will the chromosomes move to the poles of the cell? no

In the Calvin cycle, how many ATP molecules are required to regenerate RuBP from five G3P molecules?

3

Approximately what wavelength of light is best absorbed by chlorophyll a, the pigment that participates directly in the light reactions?

435 nm

Which wavelength of light is best absorbed by chlorophyll b?

455 nm

For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle.

6

How many carbon dioxide molecules must be added to RuBP to make a single molecule of glucose?

6

True or false? The chemiosmotic hypothesis states that the synthesis of ATP generates a proton gradient that leads to electron flow through an electron transport chain.

False

True or false? The region of ATP synthase that catalyzes the production of ATP from ADP and inorganic phosphate spans the chloroplast membrane.

False

NADH and FADH2 are both electron carriers that donate their electrons to the electron transport chain. The electrons ultimately reduce O2 to water in the final step of electron transport. However, the amount of ATP made by electrons from an NADH molecule is greater than the amount made by electrons from an FADH2 molecule.

Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor.

Drag the numbers on the left to complete the sentence on the right. Numbers may be used once, more than once, or not at all.

For every molecule of O2 that is released by photosystem II, 2 H2O molecules are needed, which together pass 4 electrons to the PS II reaction-center complex.

Which of the following is the correct order of electron flow in the light reactions of photosynthesis?

H2O → P680 chlorophyll a pair → PS II primary electron acceptor → Pq → cytochrome complex → Pc → P700 chlorophyll a pair → PS I primary electron acceptor → Fd → NADPH

If the Calvin cycle slows down, what will happen to the rate of O2 production in PS II, and why?

O2 production will slow down because less NADP+ will be regenerated in the Calvin cycle.

Can you tell from these absorption spectra whether red light is effective in driving photosynthesis?

One cannot tell from this graph, but because chlorophyll a does absorb red light, we can predict that it would be effective in driving photosynthesis.

Which term describes ATP production resulting from the capture of light energy by chlorophyll?

Photophosphorylation

According to the chemiosmotic hypothesis, what provides the energy that directly drives ATP synthesis?

Proton gradient

Which of the following particles can pass through the ATP synthase channel?

Protons

Carbon fixation involves the addition of carbon dioxide to _____.

RuBP

When a pigment molecule in a light-harvesting complex absorbs a photon of light, what happens to its excited-state electron?

The electron falls back to its ground state, while passing its excited-state energy to an electron in a nearby pigment molecule.

If only chlorophyll a were involved in the light reactions, would blue light (wavelength about 490 nm) be effective in driving photosynthesis?

The graph indicates that chlorophyll a absorbs very little blue light, so we can predict that blue light would not be effective.

If crossing over did not occur, which of the following statements about meiosis would be true? Select all that apply.

There would be less genetic variation among gametes.

An action spectrum plots the rate of photosynthesis at various wavelengths of visible light, and it shows that blue light with a wavelength of about 490 nm is effective in driving photosynthesis. Based on this information and the absorption spectra shown at left, what role may chlorophyll b and carotenoids play in photosynthesis?

These pigments are able to absorb more wavelengths of light (and thus more energy) than chlorophyll a alone can absorb. As part of light-harvesting complexes in photosystems, they broaden the range of light that can be used in the light reactions.

You obtain the pigments called carotenoids in your diet when you eat carrots. Why do carotenoids appear yellow and orange?

They absorb blue/green light and reflect yellow and red wavelengths of light.

Which of these enters the citric acid cycle?

acetyl CoA

Which of these is NOT a product of the citric acid cycle?

acetyl CoA