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123 terms

biology

STUDY
PLAY
Which of the following structures is involved with the movement of organelles within a cell?
microtubles
are derived from the Golgi apparatus.
lysosomes
Some proteins that are on the surface of mammalian cells contain carbohydrates. These proteins are synthesized by _______ and the sugars added in the _______.
the rough endoplasmic reticulum; Golgi apparatus
Which of the following structures occupies the largest volume in a mature plant cell?
Vacuole
The extracellular matrix of animal cells
All of the above
Plant cells do not have lysosomes. Which of the following structures likely fulfills the function of lysosomes in plant cell?
Vacuole
Which of the following organelles were probably once independent prokaryote organisms?
Mitochondria and chloroplasts
Plastids are
present in nearly all plant cells
Prokaryotes
are surrounded by a plasma membrane.
Which one of the following organelles is thought to have arisen from an endosymbiotic relationship with a prokaryote?
Mitochondria
The endomembrane system
includes the Golgi apparatus and the endoplasmic reticulum.
Which of the following is not a function of the plasma membrane of eukaryotes?
Adhering to other cells
Which of the following statements best describes what happens to the organelles of the pepper fruit cells as the fruit turns from green to red?
Chloroplasts become chromoplasts
Which of the following statements about the nucleus in animal cells is false?
The nucleus is the site of protein synthesis
moves organelles within cells
The cytoskeleton
Which of the following organelles is involved in energy conversions?
Chloroplasts
Which of the following proteins powers both the movement of cilia and vesicles within a cell?
Dynein
Cilia and eukaryotic flagella
must have a motor protein that uses the energy of ATP hydrolysis to power movement.
Which one of the processes listed below is not carried out by the smooth endoplasmic reticulum?
protein synthesis
Nucleic acids are not found in which of the following structures?
Plant vacuoles
Osmosis is
the diffusion of water across membranes.
Membranes may
all of the above
What would happen if a suspension of red blood cells in an isotonic NaCl solution was suddenly diluted with pure water by a factor of ten?
The cells would swell and lyse (burst).
In facilitated diffusion,
specific integral membrane proteins mediate transport.
The _______ of animal cells resemble the _______ of plant cells.
gap junctions; plasmodesmata
Receptor-mediated endocytosis
results in the formation of clathrin-coated vesicles
In animals, cell recognition
involves proteins in plasma membranes.
Which of the following is not a function of exocytosis?
Lysosome formation
How can water, a polar molecule, cross biological membranes rapidly?
Both b and d
In addition to the bilayer lipids and proteins, membranes may contain _______ in the form of _______ and _______.
carbohydrates; glycoproteins; glycolipids
Phospholipids spontaneously form bilayer structures, but oils form small droplets. Why do oils not form bilayers?
Oils do not have the polar head group that phospholipids have.
The specificity of ion channels for the ions they transport is
a result of the characteristics of the channel protein.
Which of the following molecules do you think would diffuse across a phospholipid bilayer fastest, assuming that there are no proteins associated with the bilayer. (Hint: keep in mind the nature of the interior of the bilayer).
NH(base)3
Facilitated diffusion
is carried out by proteins that exhibit specificity for the molecules they transport.
A comparison of the properties of the plasma membrane to those of the membrane of lysosomes would reveal that
the two membranes have different proteins and lipids.
The sodium-potassium pump (or Na+-K+ pump)
results in the formation of a membrane potential across the plasma membrane.
A voltage difference is maintained across the plasma membrane. This voltage difference
arises because the sodium-potassium pump pumps 2 K+ in and 3 Na+ out during one catalytic cycle.
The biochemical reactions of biological membranes are carried out by _______ that may be either in contact with the interior of the bilayer (_______ to the membrane) or arranged on either side of the bilayer (_______ to the membrane).
proteins; integral; peripheral
Secondary active transport resembles transport by ion channels in that
both types of transport can involve the movement of Na+ across the plasma membrane
Which of the following statements about membrane proteins is false?
Hydrophilic regions of integral membrane proteins are in contact with the interior of the bilayer.
A competitive inhibitor of the activity of an enzyme
binds to the active site of the enzyme
To be metabolized, glucose must be converted to glucose 6-phosphate. However, at equilibrium, a mixture of glucose and phosphate at concentrations that exist in cells would contain little glucose 6-phosphate. How do cells circumvent this problem?
ATP, not Pi, is used as the donor of the phosphoryl group, and, thus, the formation of glucose 6-phosphate is exergonic.
An allosteric enzyme
is related to the disorder or randomness of a system
Suppose the reaction A ↔ B has a large, negative ΔG. In what direction, how far, and how fast will the reaction proceed?
From A to B; at equilibrium mostly B would be present; insufficient information is given to predict the rate of the reaction
Entropy
is related to the disorder or randomness of a system
The binding of a substrate to an enzyme
may involve hydrogen bonds and van der Waals interactions
If ΔG for a reaction is positive, the reaction
is endergonic
A reaction that has a negative ΔG
spontanious
A competitive inhibitor of an enzyme-catalyzed reaction
is usually structurally similar to the substrate
A prosthetic group of an enzyme
participates in the reaction catalyzed by the enzyme
The synthesis of complex molecules is _______, whereas their degradation is _______. Synthesis occurs with _______ in entropy.
endergonic; exergonic; a decrease
Enzymes
may be subject to feedback inhibition
Which of the following effectors of enzyme activity is least likely to be of importance in cells?
Irreversible inhibitors
Which of the following parameters determines how far and in what direction a reaction will proceed?
ΔG
Why is the statement, "ATP produces energy for life," wrong?
It is a violation of the first law of thermodynamics
In a reaction catalyzed by an enzyme
the enzyme does not affect the equilibrium constant for the reaction
The rate of a reaction catalyzed by an enzyme that has a single polypeptide chain
may be increased or decreased by temperature
An enzyme could increase the rate of a reaction by
All of the above
Which of the following statements is (are) inconsistent with the first and second laws of thermodynamics?
a and c
Which of the following statements about ATP is false?
The phosphate bond energy of ATP is used to power catabolic metabolism
The DNA of prokaryotic cells is found in the
nucleotide
An organelle found only in plant cells is the
chloroplast
The idea that Eukaryotic cells are derived from prokaryotic cells living together in a mutualistic relationship is the
Endosymbiotic theory
The ability of some materials to move through biological membranes more readily than others is called selective
permeability
If a cell placed within a solution shrinks, the solution is ____ relative to the cell
hypertonic
A protein that forms an ion channel through a membrane is most likely
an integrel protein
4. The electric signal for contraction passes rapidly from one muscle cell to the next by way of
gap junctions
5. Active transport is important because it can move molecules
c. That resist osmosis
1. Cells mostly use ATP as an immediate source of ____to drive reactions
energy
2. The second law of thermodynamics is that___is always increasing
disorder/enthropy
3. How does a competitive inhibitor inhibit binding of a substrate to an enzyme
b. It binds to the active site
4. Enzymes
a. Can de denatured
5. Which statement about enzymes is true
c. They don't change the value of (delta) G of the reaction
1. Oxidation and ___ occur together
reduction
2. Due to its ability to carry electrons and free energy, ____ is the most common electron carrier in cells
NAD+
3. In human muscle cells, the fermentation process produces
lactic acid
4. The proton-motive force is
b. The proton concentration gradient and electric charge difference
5. Most ATP produced in our bodies is made
c. Using chemiosmosis and ATP synthase
1. During the light reactions of photosynthesis the synthesis of_____ is coupled to the diffusion of protons.
ATP synthase
2. Oxygen (O2) exits plant leaves through openings called
Stoma
3. How do red and blue light differ from one another
c. Their wavelengths are different
4. The photosynthetic pigment chlorophyll a absorbs
d. Orange-red and blue light
5. During cyclic photophosphorylation, the energy to produce ATP is provided by
(last question)
d. The redox reactions of the electron transport chain
The end products of glycolysis are
acetylCoA, ATP, and NADH
The electron transport chain of mitochondria
contains cytochromes and proteins containing flavins (FAD
In the complete oxidation of glucose, 6 CO2 molecules are formed per glucose oxidized. Choose from the list below the correct numbers of CO2 molecules released by glycolysis (gly), the citric acid cycle (CAC), and pyruvate oxidation (pyr).
gly 0; CAC 4; pyr 2
Acetyl CoA
is formed in the cytosol during the complete oxidation of glucose
What is the metabolic fate of pyruvate in anaerobic muscle
It is reduced to lactate
The conversion of malate to oxaloacetate in the citric acid cycle takes place with the conversion of NAD+ to NADH. In this reaction, NAD+ is
b, c
Which of the compounds listed below link(s) glycolysis and the citric acid cycle to the mitochondrial electron transport chain?
a, c
Reagents, such as dinitrophenol, increase the permeability of the mitochondrial inner membrane to protons. The addition of dinitrophenol to a suspension of animal cells should
inhibit mitochondrial ATP synthesis
The synthesis of ATP from ADP and Pi is an _______ reaction. In mitochondria, ATP synthesis is driven by the flow of _______ down the concentration and electrical gradient established by _______.
endergonic; protons; electron transport
Which of the statements below about the citric acid cycle is false?
The cycle releases less energy than glycolysis
The mitochondrial electron transport chain
oxidizes the intermediate electron carriers, NADH and FADH2
Most of the ATP made during the complete oxidation of glucose to CO2 and water is
made by the mitochondrial ATP synthase
Which one of the following reactions is not an oxidation-reduction reaction?
R-CH=CH-CH3 + H2O ↔ RCH2-CH(OH)-CH3
Glycolysis
is an oxidation-reduction process
Triglycerides are major energy storage molecules. Which statement about the complete oxidation of triglycerides to CO2 and water and the oxidation of glucose to two molecules of pyruvate is correct?
Only glucose oxidation uses the glycolytic pathway.
The mitochondrial ATP synthase
makes ATP at the expense of the proton gradient established by electron transport.
Cyanide inhibits the enzyme in the mitochondrial electron transport chain that reduces O2 to water. Suppose that you add cyanide to a suspension of muscle cells from a rat. Which statement given below is the most accurate with respect to the effects of cyanide on glucose catabolism?
The citric acid cycle would be inhibited, but glycolysis would not. Lactic acid accumulates.
The synthesis of ATP from ADP and Pi by mitochondria
is linked to electron transport
A suspension of yeast supplied with glucose as its source of energy was transferred from an aerobic environment to an anaerobic one. What do you think would happen to the rate of glucose utilization and the rate of ethanol production after the transfer?
Both glucose usage and ethanol production would increase.
Fermentation
results in the formation of lactic acid or ethanol
Which of the following is not a characteristic of C4 plants?
The first product of photosynthesis in C4 plants is 3PG
In green plant photosynthesis, water is
oxidized to oxygen gas (O2) in the light
In C3 photosynthesis, NADPH is used for the
reduction of 3-phosphoglycerate (3-PG)
Photorespiration
decreases the efficiency of photosynthesis in C3 plants
The _______ of photosynthesis is similar to the _______ of chlorophylls.
action spectrum; absorption spectrum
The concentration of CO2 in Earth's atmosphere has increased over the past 200 years. If this trend continues, as seems likely, what could happen to photosynthesis? Ignore global warming and assume that the content of oxygen in the atmosphere will not change.
The net yield C3 photosynthesis should increase; C4 photosynthesis should be unaffected.
In addition to driving the synthesis of ATP and the reduction of NADP+ to NADPH, light stimulates the Calvin cycle by _______ and _______.
increasing the pH of the stroma; reduction of some enzymes
Which statement given below best characterizes the properties of a photosystem?
A photosystem is a complex of pigments, proteins, and a reaction center chlorophyll
C4 plants have _______ rates of _______ than C3 plants because the ratio of the concentrations of CO2 to that of O2 is _______ in C4 plants.
lower; photorespiration; higher
If you were to grow a green plant in a lighted chamber in the presence of radioactive carbon dioxide for several days, which of the following types of compounds in the plant would be radioactive?
all the above
The immediate source of energy for ATP synthesis in chloroplasts is
the electrochemical proton gradient
Mesophyll cells of a leaf of a green plant
have metabolic pathways that are very similar to those in animal cells, except for photosynthesis
Which of the following statements about the role of chlorophyll in photosynthesis is false?
Most of the chlorophyll in a plant participates in an oxidation/reduction reaction
Which of the following statements about the light-independent reactions of photosynthesis is not correct?
The light-independent reactions operate in the dark
The major product of photosynthesis that is exported from the leaves to the rest of the plant is
sucrose
The ultimate source of energy for ATP synthesis in chloroplasts is
light
Plants that carry out crassulacean acid metabolism (CAM) differ from C4 plants in that
their stomates are open at night
Cyclic electron transport
is coupled to proton uptake into the thylakoid lumen
Reaction center chlorophylls
are oxidized when in the excited state
The products of noncyclic electron transport are
NADPH, O2, and ATP