Which of the following is an example of potential rather than kinetic energy?
- the muscle contractions of a person mowing grass
- water rushing over Niagara falls
- light flashes emitted by a firefly
- a molecule of glucose
- the flight of an insect foraging for food
d
Which of the following is (are) true for anabolic pathways?
- they do not depend on enzymes
- they are usually highly spontaneous chemical reactions
- they consume energy to build up polymers from monomers
- they release energy as they degrade polymers to monomers
- they consume energy to decrease the entropy of the organism and its environment
c
Which of the following is true for all exergonic reactions?
- the products have more total energy than the reactants
- the reaction proceeds with a net release of free energy
- the reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants
- a net input of energy from the surroundings is required for the reactions to proceed
- the reactions are rapid
b
When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?
- it is used to power yet more cellular work
- it is used to store energy as more ATP
- it is used to generate ADP from nucleotide precursors
- it is lost to the environment
- it is transported to specific organs such as the brain
d
According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?
- the binding of the substrate depends on the shape of the active site
- some enzymes change their structure when activators bind to the enzyme
- a competitive inhibitor can outcompete the substrate for the active site
- the binding of the substrate changes the shape of the enzymes active site
- the active site creates a microenvironment ideal for the reaction
d
When you have a severe fever, what grave consequence may occur if the fever is not controlled?
- destruction of your enzymes' primary structure
- removal of amine groups from your proteins
- change in the tertiary structure of your enzymes
- removal of the amino aids in active sites of your enzymes
- binding of your enzymes to inappropriate substrates
c
The mechanisms in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as
- metabolic inhibition
- feedback inhibition
- allosteric inhibition
- noncooperative inhibition
- reversible inhibition
b
Which of the following is true of enzymes?
- nonprotein cofactors alter the substrate specificity of enzymes
- enzyme function is increased if the 3D structure or conformation of an enzyme is altered
- enzyme function is independent of physical and chemical environmental factors such as pH and temperature
- enzymes increase the rate of chemical reaction by lowering activation energy barriers
- enzymes increase the rate of chemical reaction by providing activation energy to the substrate
d
Which curve(s) on the graphs above 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 70C or higher?
- curves 1 and 5
- curves 2 and 4
- curves 2 and 5
- curves 3 and 4
- curves 3 and 5
e
The following question is based on the reaction A+B <--> C+D shown in Figure 8.1 Which of the following represents the activation energy required for the enzyme-catalyzed reaction in Figure 8.1?
- a
- b
- c
- d
- e
b
Some bacteria are metabolically active in hot springs because
- they are able to maintain a lower internal temperature
- high temperatures make catalysis unnecessary
- their enzymes have high optimal temperatures
- their enzymes are completely insensitive to temperature
- they use molecules other than proteins or RNAs as their main catalysts
c
Which of the following statements describes the results of this reaction? C6H1206 --> 6CO2 + 6H20 + Energy
- C6H12O6 is oxidized and O2 is reduced
- O2 is oxidized and H2O is reduced
- CO2 is reduced and O2 is oxidized
- C6H12O6 is reduced and CO2 is oxidized
- O2 is reduced and CO2 is oxidized
a
During aerobic respiration, electrons travel downhill in which sequence?
- food --> citric acid cycle --> ATP --> NAD+
- food --> NADH --> electron transport chain --> oxygen
- glucose --> pyruvate --> ATP --> oxygen
- glucose --> ATP --> electron transport chain --> NADH
- food --> glycolysis --> citric acid cycle --> NADH --> ATP
b
The ATP made during glycolysis is generated by
- substrate-level phosphorylation
- electron transport
- photophosphorylation
- chemiosmosis
- oxidation of NADH to NAD+
a
Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?
- electron transport
- glycolysis
- the citric acid cycle
- oxidative phosphorylation
- chemiosmosis
b
The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is
- oxygen
- water
- NAD+
- pyruvate
- ADP
a
Where are the proteins of the electron transport chain located?
- cytosol
- mitochondrial outer membrane
- mitochondrial inner membrane
- mitochondrial intermembrane space
- mitochondrial matrix
c
What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ --> Lactate + Nad+
- oxygen
- NADH
- NAD+
- lactate
- pyruvate
e
How many carbon dioxide molecules are released during cellular respiration as a result of the oxidation of one molecule of glucose?
- two
- four
- six
- eight
- ten
c
Why are carbohydrates and fats considered high energy foods?
- they have a lot of oxygen atoms
- they have no nitrogen in their makeup
- they can have very long carbon skeletons
- they have a lot of electrons associated with hydrogen
- they are easily reduced
d
Which of the following intermediary metabolites enters the citric acid cycle and is formed, in part, by the removal of a carbon (CO2) from one molecule of pyruvate?
- lactate
- glyceraldehydes-3-phosphate
- oxaloacetate
- acetyl CoA
- citrate
d
Which of the following is characterized by a cell releasing a signal molecule into the environment followed by a number of cells in the immediate vicinity responding?
- hormonal signaling
- autocrine signaling
- paracrine signaling
- endocrine signaling
- synaptic signaling
c
Testosterone functions inside a cell by
- acting as a signal receptor that activates tyrosine kinases
- binding with a receptor protein that enters the nucleus and activates specific genes
- acting as a steroid signal receptor that activates ion channel proteins
- becoming a second messenger that inhibits adenylyl cyclase
- coordinating a phosphorylation cascade that increases spermatogenesis
b
Which of the following is true of transcription factors?
- they regulate the synthesis of DNA in response to a signal
- they transcribe ATP into cAMP
- they initiate the epinephrine response in animal cells
- they control gene expression
- they regulate the synthesis of lipids in the cytoplasm
d
In the formation of biofilms, such as those forming on unbrushed teeth, cell signaling serves which function?
- formation of mating complexes
- secretion of apoptotic signals
- aggregation of bacteria that can cause cavities
- secretion of substances that inhibit foreign bacteria
- digestion of unwanted parasite populations
c
Which of the following statements about quorum sensing is FALSE? Quorum sensing
- is cell-cell communication in eukaryotes
- is species specific
- may result in biofilm formation
- is particularly well studied because of its medical importance
a
In general, a signal transmitted via phosphorylation of a series of proteins
- brings a conformational change to each protein
- requires binding of a hormone to a cytosol receptor
- cannot occur in yeasts because they lack protein phosphatases
- requires phosphorylase activity
a
In the figure, the dots in the space between the two structures represent which of the following?
- receptor molecules
- signal transducers
- neurotransmitters
- hormones
- pheromones
c
What explains the increased concentration of Ca++ in the ER?
- calcium ions are actively imported from the cytoplasm into the ER
- calcium concentration is kept low in the cytoplasm because of its high usage level
- calcium cannot enter the plasma membrane through ion channels
- calcium levels in the blood or other body fluids are extremely low
- the Ca ions are recycled from other molecules in the ER
a
Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells but affect only target cells because
- only target cells retain the appropriate DNA segments
- intracellular receptors are present only in target cells
- most cells lack the Y chromosome required
- only target cells possess the cytosolic enzymes that transduce the testosterone
- only in target cells in testosterone able to initiate the phosphorylation cascade leading to activated transcription factor
b
Which of the following describes the events of apoptosis?
- the cell dies, it is lysed, its organelles are phagocytized, and its contents are recycled
- its DNA and organelles become fragmented, it dies, and it is phagocytized
- the cell dies and the presence of its fragmented contents stimulates nearby cells to divide
- its DNA and organelles are fragmented, the cell shrinks and forms blebs, and the cell debris is digested
- its nucleus and organelles are lysed, then the cell enlarges and bursts
d
The centromere is a region in which
- chromatids remain attached to one another until anaphase
- metaphase chromosomes become aligned at the metaphase plate
- chromosomes are grouped during telophase
- the nucleus is located prior to mitosis
- new spindle microtubules form at either end
a
If cells in the process of dividing are subjected to colchicine, a drug that interferes with the formation of the spindle apparatus, at which stage will mitosis be arrested?
- anaphase
- prophase
- telophase
- metaphase
- interphase
d
Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants
- the spindles contain microfibrils in addition to microtubules, whereas animal spindles do not contain microfibrils
- sister chromatids are identical, but they differ from one another in animals
- a cell plate begins to form at telophase, whereas animals a cleavage furrow is initiated at that stage
- chromosomes become attached to the spindle at prophase, whereas in animals chromosomes do not become attached until anaphase
- spindle poles contain centrioles, whereas spindle poles in animals do not
c
During which phase of mitosis do the chromatids become chromosomes?
- telophase
- anaphase
- prophase
- metaphase
- cytokinesis
a
Which of the following is true concerning cancer cells?
- they do not exhibit density-dependent inhibition when growing in culture
- when they stop dividing, they do so at random points in the cell cycle
- they are not subject to cell cycle controls
- when they stop dividing, they do so at random points in the cell cycle, and they are not subject to cell cycle controls
- when they stop dividing, they do so at random points in the cell cycle; they are not subject to cell cycle controls; and they do not exhibit density-dependent inhibition when growing in culture.
e
After telophase I of meiosis, the chromosomal makeup of each daughter cell is
- diploid, and the chromosomes are each composed of a single chromatid
- diploid, and the chromosomes are each composed of two chromatids
- haploid, and the chromosomes are each composed of a single chromatid
- haploid, and the chromosomes are each composed of two chromatids
- tetraploid, and the chromosomes are each composed of two chromatids
d
Which of the following occurs in meiosis but not in mitosis?
- chromosome replication
- synapsis
- production of daughter cells
- alignment of tetrads at metaphase plate
- both B and D
b
Figure 13.2 of a single pair of homologous chromosomes as they might appear during various stages of either mitosis or meiosis, and answer the following question.
Which diagram represents prophase I of meiosis?
- I
- II
- III
- IV
- V
d
Which of the following is true of the process of meiosis?
- two diploid cells result
- four diploid cells result
- four haploid cells result
- four autosomes result
- four chiasmata result
c