exam 2 review Flashcards
how do living organism create macromolecules?
create order locally, but energy transformations generate waste heat, and increase entropy in the universe
for living organisms, which of the following is an important consequence of the first law of thermodynamics?
organism ultimately must obtain all of the necessary energy for life from its environment
when ATP releases some energy, it also releases inorganic phosphate. what purpose does this serve in the cell?
phosphate may be incorporated into many different molecules
all the energy to power life comes from the sun, and photosynthetic organisms are the base of the food chain.
true, because organisms aren’t the only base of the food chain though
the molecule that functions as the reducing agent (electron donor) in a redox or oxidation reaction…
loses electrons and loses potential energy
cellular respiration can be best described as…
taking electrons from food and giving them to oxygen to make water, and using the energy released to make ATP
when a molecule of NAD+ gains one hydrogen atom (a proton and an electron) and an additional electron, the molecule is ________ and becomes NADH.
what is the seventh reaction of glycolysis?
the energetic electron, taken from glucose or a breakdown product of glucose, is stripped of its energy to…
actively transport H+ into the intermembrane space
ATP synthase at the inner mitochondrial membrane makes ATP by which method?
facilitated diffusion of H+
in chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP+ phosphorylation to ATP?
energy released from movement of protons through ATP synthase
where did the carbons found throughout the body of a plant originate?
the light reactions, which involve the very hydrophobic chlorophyll, are located where in the chloroplast?
the calvin cycle reactions are located where in the chloroplasts?
plants photosynthesize only in the light. plants respire…
both in the light and dark
by matching the absorption spectrum of pigments in chloroplasts with the action spectrum of photosynthesis, it is possible to determine…
which pigments are involved in the light reactions
what can happen when a photon of light strikes a pigment, such as chlorophyll a?
photon is absorbed, and the resulting energy propels an electron in the molecule to an elevated outer electron shell where it has more energy potential
which of the following correctly identifies the products of photosystems 1 and 2?
1: P700 and NADPH
2: O2 and P680+
which of the following sequences correctly represent the flow of electrons during photosynthesis?
H2O, NADPH, calvin cycle
how are light reactions and the calvin cycle connected?
light reactions provide ATP and NADPH to the calvin cycle, and the calvin cycle returns ADP, phosphate, and NADP+ to the light reactions
succulent plants that are able to thrive in the desert have a specialized type of photosynthesis called CAM. these plants have an adaptation for photosynthesis whereby they…
perform the light reactions of photosynthesis during day light and fix CO2 at night; reduce water loss by keeping their stromata closed during the day
which items are provided to you by photosynthesis?
oxygen in your latest breath
starch in the toast
paper in textbook
what is the term for metabolic pathways that release stored energy by breaking down complex molecules?
whenever energy is transformed, there is always an increase in the…
entropy of the universe
the mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as…
which of the following statements describes NAD+?
NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle
which of the following statements describes NADH?
NADH is oxidized for NAD+ at the electron transport chain and in the fermentation
where does glycolysis take place in eukaryotic cells?
the ATP made during glycolysis is generated by…
why are carbohydrates and fats considered high energy foods?
they have a lot of electrons associated with hydrogens
the primary role of oxygen in cellular respiration is to…
act as an acceptor for electrons and hydrogen, forming water
inside an active mitochondrion, most electrons follow which pathway?
citric acid cycle – NADH – electron transport chain – oxygen
energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?
mitochondrial intermembrane space
which of the following occurs in the cytosol of a eukaryotic cell?
glycolysis and fermentation
in chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP + Pi to ATP?
energy released from ATP synthase pumping hydrogen ions from the mitochondrial matrix
which of the following sequences correctly represents the flow of electrons during photosynthesis?
H2O – NADPH – calvin cycle
if photosynthesizing green algae are provided with CO2 synthesized with heavy oxygen, later analysis will show that all but one of the following produced by the algae contain the heavy oxygen label. that is…
which of the following are products of the light reactions of photosynthesis that are utilized in the calvin cycle?
ATP and NADPH
in the thylakoid membranes, what is the main role of the antenna pigment molecules?
harvest photons and transfer light energy to the reaction-center chlorophyll
when oxygen is released as a result of photosynthesis, it is a direct by-product of…
splitting water molecules
P680+ is said to be the strongest biological oxidizing agent. why?
this molecule has a stronger attraction for electrons that oxygen, to obtain electrons from water
why is ATP an important molecule in metabolism?
it provides energy coupling between exergonic and endergonic reactions
which of the following statements regarding enzymes is true?
enzymes increase the rate of a reaction by lowering the activation energy barrier
why is glycolysis considered to be one of the first metabolic pathways to have evolved?
it does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms
which of the following statements best describes the relationship between photosynthesis and respiration?
photosynthesis stores energy in complex organic molecules, whereas respiration releases it
the oxygen atoms in the H2O broken down during photosynthesis end up in…
molecular O2 released during photosynthesis
during glycolysis, for each mole of glucose oxidized to pyruvate…
2 moles of ATP are used, and 4 moles of ATP are produced
what carbon sources can yeast cells metabolize to make ATP from ADP under anaerobic conditions?
the biomass (dry weigh) of a tree comes primarily from…
in thylakoids, protons travel through ATP synthase from the thylakoid space to the stroma. therefore, the catalytic “knobs” of ATP synthase would be located…
on the outside of the inner membrane facing stroma
assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. this damage will have the most direct effect on which of the following processes?
the synthesis of ATP
which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
which of the following are true for anabolic pathways?
they consume energy to build up polymers from monomers
which of the following is a statement of the first law of thermodynamics?
energy cannot be created or destroyed
living organism increase in complexity as they grow, resulting in a decrease in the entropy of an organism. how does this relate to the second law of thermodynamics?
as a consequence of growing, organisms create more disorder in the environment than the decrease in entropy associated with their growth
Which of the following statements is a logical consequence of the second law of thermodynamics?
Every chemical reaction must increase the total entropy of the universe.
Which of the following statements is representative of the second law of thermodynamics?
Cells require a constant input of energy to maintain their high level of organization
what doesn't occur during the calvin cycle?
release of oxygen
Which of the following statements is a correct distinction between autotrophs and heterotrophs?
Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic.
The pH of the inner thylakoid space has been measured, as have the pH of the stroma and of the cytosol of a particular plant cell. Which, if any, relationship would you expect to find?
the pH within the thylakoid is less than that of the stroma
P680+ is said to be the strongest biological oxidizing agent. Why?
This molecule results from the transfer of an electron to the primary electron acceptor of photosystem II and strongly attracts another electron.
Which statement describes the functioning of photosystem II?
The electron vacancies in P680 are filled by electrons derived from water
What is the reducing agent in the following reaction? Pyruvate + NADH + H+ → Lactate + NAD+
Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, an early step of glycolysis. In the presence of oxygen, an increase in the amount ATP in a cell would be expected to
inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle
What is proton-motive force?
the transmembrane proton concentration gradient
What must be the difference (if any) between the structure of ATP and the structure of the precursor of the A nucleotide in DNA and RNA?
How can one increase the rate of a chemical reaction?
Add a catalyst
Sucrose is a disaccharide, composed of the monosaccharides glucose and fructose. The hydrolysis of sucrose by the enzyme sucrase results in
breaking the bond between glucose and fructose and forming new bonds from the atoms of water.
According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?
The binding of the substrate changes the shape of the enzymeʹs active site.
The following questions are based on the reaction A + B → C + D
Which of the following terms best describes the reaction?
When you have a severe fever, what may be a grave consequence if this is not controlled?
change in the folding of enzymes
How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?
by changing the shape of a reactant
When electrons move closer to a more electronegative atom, what happens?
energy is released, and the more electronegative atom is reduced
Which of the following statements describes the results of this reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy
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
A molecule that is phosphorylated
has an increased chemical reactivity; it is primed to do cellular work
Which process is most directly driven by light energy?
removal of electrons from chlorophyll molecules
How is photosynthesis similar in C4 and CAM plants?
In both cases, rubisco is not used to fix carbon initially
In mechanism, photophosphorylation is most similar to
oxidative phosphorylation in cellular respiration.
The light reactions of photosynthesis supply the Calvin cycle with
ATP and NADPH
If plant gene alterations cause the plants to be deficient in photorespiration, what would most probably occur?
Less ATP would be generated
The alternative pathways of photosynthesis using the C4 or CAM systems are said to be compromises. Why?
Each one both minimizes photorespiration and optimizes the Calvin cycle
Photorespiration lowers the efficiency of photosynthesis by preventing the formation of A) carbon dioxide molecules
CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they
fix CO2 into organic acids during the night
Why are C4 plants able to photosynthesize with no apparent photorespiration
They use PEP carboxylase to initially fix CO2
Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be
to test for liberation of O2 in the light.
A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are being absorbed by this pigment?
blue and violet
What are the products of the light reactions that are subsequently used by the Calvin cycle?
ATP and NADPH
Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as __________ is to __________.
Which of the following metabolic processes can occur without a net influx of energy from some other process?
C6H12O6 + 6 O2 → 6 CO2 + 6H2O
The oxygen consumed during cellular respiration is involved directly in which process or event?
accepting electrons at the end of the electron transport chain
Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?
During glycolysis, when glucose is catabolized to pyruvate, most of the energy of glucose is
retained in the pyruvate
Starting with one molecule of isocitrate and ending with fumarate, what is the maximum number of ATP molecules that could be made through substrate-level phosphorylation?
Which of the following couples chemiosmosis to energy storage?
in the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of
ATP, CO2, and ethanol (ethyl alcohol).
Assume that the reaction has a △G of -5.6 kcal/mol. Which of the following would be true?
The reaction would result in an increase in entropy (S) and a decrease in the total energy content (H) of the system.
In order to attach a particular amino acid to the tRNA molecule that will transport it, an enzyme, an aminoacyl-tRNA synthetase, is required, along with ATP. Initially, the enzyme has an active site for ATP and another for the amino acid, but it is not able to attach the tRNA. What must occur in order for the final attachment to occur?
The binding of the first two molecules must cause a 3-dimensional change that opens another active site on the enzyme.
Competitive inhibitors block the entry of substrate into the active site of an enzyme. On which of the following properties of an active site does this primarily depend?
the ability of an enzyme to form a template for holding and joining molecules
Which of the following is likely to lead to an increase in the concentration of ATP in a cell?
an increase in a cellʹs catabolic activity
Which of the following statements describes enzyme cooperativity?
A substrate molecule bound to an active site affects the active site of several subunits
Which of the following is an example of cooperativity?
a molecule binding at one unit of a tetramer allowing faster binding at each of the other three
In the process of carbon fixation, RuBP attaches a CO2 to produce a 6 carbon molecule,
which is then split in two. After phosphorylation and reduction, what more needs to happen in the Calvin cycle?
regeneration of rubsico
The sugar that results from three ʺturnsʺ of the Calvin cycle is glyceraldehyde-3-phosphate (G3P). Which of the following is a consequence of this?
The formation of starch in plants involves assembling many G3P molecules, with or without further rearrangements.
neither the light reactions nor the Calvin cycle
the Calvin cycle alone
Produces three-carbon sugars
the Calvin cycle alone
light reactions alone
neither the light reactions nor the Calvin cycle
Produces molecular oxygen (O2)
light reactions alone
the Calvin cycle alone
What is the primary function of the Calvin cycle?
synthesize simple sugars from carbon dioxide
Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?
The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, Pi, and NADP+ to the light reactions.
Where do the enzymatic reactions of the Calvin cycle take place?
stroma of the chloroplast
Which of the following types of reactions would decrease the entropy within a cell?
The organization of organisms has become increasingly complex with time. This statement
is consistent with the second law of thermodynamics
Which of the following is an example of potential rather than kinetic energy?
a food molecule made up of energy-rich macromolecule
Which of the following is considered an open system
Which of the following is true of metabolism in its entirety?
Metabolism is a property of organismal life
The mathematical expression for the change in free energy of a system is △G =△H-T△S. Which of the following is (are) correct?
△G is the change in free energy.
What is the change in free energy of a system at chemical equilibrium
no net change
Which of the following is true for all exergonic reactions?
The reaction proceeds with a net release of free energy.
Chemical equilibrium is relatively rare in living cells. Which of the following could be an example of a reaction at chemical equilibrium in a cell?
a chemical reaction in which both the reactants and products are only used in a metabolic pathway that is completely inactive
A chemical reaction that has a positive △G is correctly described as
Which of the following best describes enthalpy (H)?
the heat content of a chemical system
Which of the following is most similar in structure to ATP?
an RNA nucleotide
What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways
Which of the following statements is true concerning catabolic pathways?
They are usually coupled with anabolic pathways to which they supply energy in the form of ATP.
When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?
It is lost to the environment
Which of the following statements is (are) true about enzyme-catalyzed reactions?
The reaction is faster than the same reaction in the absence of the enzyme.
Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?
The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation is
the difference in H+ concentrations on opposite sides of the inner mitochondrial membrane.
When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the
creation of a proton gradient.
Which of the following normally occurs whether or not oxygen (O2) is present?
Why is glycolysis considered to be one of the first metabolic pathways to have evolved?
It is found in the cytosol, does not involve oxygen, and is present in most organisms
Muscle cells, when an individual is exercising heavily and when the muscle becomes oxygen deprived, convert pyruvate to lactate. What happens to the lactate in skeletal muscle cells?
It is taken to the liver and converted back to pyruvate
Cyclic electron flow may be photoprotective (protective to light-induced damage). Which of the following experiments could provide information on this phenomenon?
using mutated organisms that can grow but that cannot carry out cyclic flow of electrons and compare their abilities to photosynthesize in different light intensities
Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants?
They dissipate excessive light energy
Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy?
Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O).
In addition to ATP, what are the end products of glycolysis?
NADH and pyruvate
Starting with one molecule of glucose, the ʺnetʺ products of glycolysis are
2 NADH, 2 H+, 2 pyruvate, 2 ATP, and 2 H2O
How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate?
Why is glycolysis described as having an investment phase and a payoff phase?
It uses stored ATP and then forms a net increase in ATP.
How does pyruvate enter the mitochondrion
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?
During cellular respiration, acetyl CoA accumulates in which location
How many molecules of carbon dioxide (CO2) would be produced by five turns of the citric acid cycle
Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?
oxidation of pyruvate to acetyl CoA and the citric acid cycle
During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?
Reduction of NADP+ occurs during
One function of both alcohol fermentation and lactic acid fermentation is to
oxidize NADH to NAD+.
Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
ATP and NADPH
What does the chemiosmotic process in chloroplasts involve?
establishment of a proton gradient
Reduction of oxygen which forms water occurs during
Most CO2 from catabolism is released during
the citric acid cycle
In glycolysis, for each molecule of glucose oxidized to pyruvate
2 molecules of ATP are used and 4 molecules of ATP are produced
For each molecule of glucose that is metabolized by glycolysis and the citric acid cycle, what is the total number of NADH + FADH2 molecules produced?
Cellular respiration harvests the most chemical energy from which of the following?
Where are the proteins of the electron transport chain located?
mitochondrial inner membrane
Each time a molecule of glucose (C6H12O6) is completely oxidized via aerobic respiration, how many oxygen molecules (O2) are required?
Which of the following is a true distinction between fermentation and cellular respiration?
NADH is oxidized by the electron transport chain in respiration only.
The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is
Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?