Which of the following statements regarding enzymes is true?

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Enzymes increase the rate of a reaction by lowering the activation energy barrier.

The active site of an enzyme is the region that

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is involved in the catalytic reaction of the enzyme.

When you have a severe fever, what grave consequence may occur if the fever is not controlled?

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change in the tertiary structure of your enzymes

How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?

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by changing the shape of the enzyme's active site

Activity of various enzymes at various temperatures (a) and at various pH (b).

Which curve(s) on the graphs may represent the temperature and pH profiles of an enzyme taken from a bacterium that lives in a mildly alkaline hot springs at temperatures of 70°C or higher?

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curves 3 and 5

Activity of various enzymes at various temperatures (a) and at various pH (b).

Which temperature and pH profile curves on the graphs were most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid?

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curves 1 and 4

Which of the following terms best describes the forward reaction in the figure?

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exergonic, Δ G < 0

Which of the following represents the ΔG of the reaction in the figure?

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d

The following question is based on the reaction A + B ↔ C + D shown in the figure.

Which of the following in the figure would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?

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d

Which of the following represents the activation energy required for a noncatalyzed reaction in the figure?

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c

The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as

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feedback inhibition.

A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme.

What is substance X?

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a substrate

Which of the following clues would tell you if a cell is prokaryotic or eukaryotic?

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whether or not the cell is partitioned by internal membranes

Which of the following correctly matches an organelle with its function?

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central vacuole ... storage

But remember, plant cells have a central vacuole, whereas most animal cells have several smaller vacuoles located throughout the cytoplasm.

All of the following are part of a prokaryotic cell except

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an endoplasmic reticulum.

Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?

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proteins

Which one of the following statements about the endomembrane system is correct?

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Proteins that will be secreted from the cell are likely to be found in closed spaces bounded by membranes of the endomembrane system.

Hydrolytic enzymes must be segregated and packaged to prevent general destruction of cellular components. Which of the following organelles contains these hydrolytic enzymes in animal cells?

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lysosome

Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large, complex, undigested lipids. Which cellular organelle must be involved in this condition?

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the lysosome

The liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and therefore abundant in liver cells?

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smooth ER

Which organelle often takes up much of the volume of a plant cell?

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vacuole

Mitochondria are found in _____.

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plant and animal cells

Which organelle is the primary site of ATP synthesis in eukaryotic cells?

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mitochondrion

A cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and mitochondria. It could be a cell from

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nearly any eukaryotic organism.

Which of the following functions is NOT associated with the cytoskeleton in eukaryotic cells?

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Movement of RNA molecules from the nucleus to the cytoplasm

Movement of vesicles within the cell depends on what cellular structures?

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microtubules and motor proteins

Property Microtubules (tubulin polymers) Microfilaments (actin filaments) Intermediate filaments Structure Hollow tubes; wall consists of 13 columns of tubulin molecules Two intertwined strands of actin, each a polymer of actin subunits Fibrous proteins supercoiled into thicker cables Diameter 25 nm with 15-nm lumen 7 nm 8-12 nm Main functions Cell motility Cell motility Anchorage

The differences among the three categories of cytoskeletal elements outlined in the table above would suggest that each of the following has specialized roles. Which of the following is a correct match? (All three elements are involved in the maintenance of cell shape.)

microtubules and chromosome movement

Cytochalasin D is a drug that prevents actin polymerization. A cell treated with cytochalasin D will still be able to

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move vesicles around the cell.

Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through

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gap junctions

In the combined processes of glycolysis and cellular respiration, what is consumed and what is produced?

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Glucose is consumed, and carbon dioxide is produced.

The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction

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loses electrons and loses potential energy.

Which of the following statements describes the results of this reaction?
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy

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C6H12O6 is oxidized and O2 is reduced.

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes

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oxidized.

When a molecule of NAD⁺ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes

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reduced.

Where does glycolysis take place in eukaryotic cells?

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cytosol

The oxygen consumed during cellular respiration is involved directly in which process or event?

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accepting electrons at the end of the electron transport chain

During glycolysis, when each molecule of glucose is catabolized to two molecules of pyruvate, most of the potential energy contained in glucose is

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retained in the two pyruvates.

In addition to ATP, what are the end products of glycolysis?

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NADH and pyruvate

A glucose molecule is completely broken down to carbon dioxide and water in glycolysis and the citric acid cycle, but together these two processes yield only a few molecules of ATP. What happened to most of the energy that the cell obtains from the oxidation of glucose?

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It is stored in NADH and FADH₂

The electrons stripped from glucose in cellular respiration end up in which compound?

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water

Where are the proteins of the electron transport chain located?

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mitochondrial inner membrane

In cellular respiration, the energy for most ATP synthesis is supplied by

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a proton gradient across a membrane.

During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?

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FADH₂

The primary role of oxygen in cellular respiration is to

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act as an acceptor for electrons and hydrogen, forming water.

How many oxygen molecules (O₂) are required each time a molecule of glucose (C₆H₁₂O₆) is completely oxidized to carbon dioxide and water via aerobic respiration,?

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6

Which of the protein complexes labeled with Roman numerals in the figure will transfer electrons to O2?

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complex IV

Which metabolic pathway is common to both cellular respiration and fermentation?

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glycolysis

In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of

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ATP, CO₂, and ethanol (ethyl alcohol).

A mutation in yeast makes it unable to convert pyruvate to ethanol. How will this mutation affect these yeast cells?

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The mutant yeast will be unable to grow anaerobically.

The photosynthetic membranes are found in the _____ in plant cells.

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chloroplasts

The Calvin Cycle

Carbon fixation involves the addition of carbon dioxide to _____.

RuBP

The Calvin Cycle

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

NADPH

The Calvin Cycle

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

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The Calvin Cycle

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

3

Metabolic pathways that release stored energy by breaking down complex molecules are called?

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catabolic pathways