Cellular Respiration, Biology Ch.8-11 (and 45)
3 stages of cell signaling
- reception - transduction - cell response
What are two mechanisms cells can use to generate ATP without using oxygen?
1) Anaerobic respiration (uses an electron transport chain) 2) Fermentation
What are the 3 stages of cellular respiration?
1) Glycolysis 2) Pyruvate oxidation/Citric acid cycle 3) Oxidative phosphorylation (electron transport chain and chemiosmosis)
How many NADH are produced by glycolysis?
2
In glycolysis, there is a net gain of ___ ATP
2
In the absence of oxygen, what is the net gain of ATP for each glucose molecule that enters glycolysis?
2 ATP
Starting with one molecule of glucose, the energy-containing products of glycolysis are - 6 CO2, 2 pyruvate, and 2 ATP. - 6 CO2, 2 pyruvate, and 30 ATP. - 2 NAD+, 2 pyruvate, and 2 ATP. - 2 NADH, 2 pyruvate, and 2 ATP. - 2 FADH2, 2 pyruvate, and 4 ATP.
2 NADH, 2 pyruvate, and 2 ATP.
In the Calvin cycle, how many ATP molecules are required to regenerate RuBP from five G3P molecules?
3
Starting with citrate, which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle (see the figure)? 38 ATP, 6 CO2, 3 NADH, and 12 FADH2 2 ATP, 2 CO2, 3 NADH, and 3 FADH2 3 ATP, 3 CO2, 3 NADH, and 3 FADH2 1 ATP, 2 CO2, 3 NADH, and 1 FADH2 3 ATP, 6 CO2, 9 NADH, and 3 FADH2
3 ATP, 6 CO2, 9 NADH, and 3 FADH2
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
How many carbon dioxide molecules must be added to RuBP to make a single molecule of glucose?
6
Which of these equations best summarizes photosynthesis?
6 CO2 + 6 H2O → C6H12O6 + 6 O2
Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C6H12O6) in aerobic cellular respiration? 4 60-64 2 15 30-32
60-64
What is aerobic respiration?
A catabolic process that use oxygen to release energy from organic fuel and sugars.
Cofactor
A cofactor, such as a vitamin, binds to an enzyme and plays a role in catalysis.
Which of the following is an example of potential rather than kinetic energy?
A molecule of glucose
What is cellular respiration? What is the chemical formula?
A process that includes both aerobic and anaerobic processes to provide energy from fuel. C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy (ATP & heat)
What happens during glycolysis?
A six carbon sugar (glucose) is split into two three carbon sugars which are then oxidized into pyruvates. NADH and ATP is also formed
Active Site
A substrate binds to an enzyme at the active site, where the reaction occurs.
Which of the following statements describes NAD⁺? A) NAD⁺ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle. B) NAD⁺ has more chemical energy than NADH. C) NAD⁺ is oxidized by the action of hydrogenases. D) NAD⁺ can donate electrons for use in oxidative phosphorylation. E) In the absence of NAD⁺, glycolysis can still function.
A) NAD⁺ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.
When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs? A) The pH of the matrix increases. B) ATP synthase pumps protons by active transport. C) The electrons gain free energy. D) The cytochromes phosphorylate ADP to form ATP. E) NAD⁺ is oxidized.
A) The pH of the matrix increases.
The transport of pyruvate into mitochondria depends on the proton-motive force across the inner mitochondrial membrane. How does pyruvate enter the mitochondrion? A) active transport B) diffusion C) facilitated diffusion D) through a channel E) through a pore
A) active transport
What carbon sources can yeast cells metabolize to make ATP from ADP under anaerobic conditions? A) glucose B) ethanol C) pyruvate D) lactic acid E) either ethanol or lactic acid
A) glucose
In glycolysis, what starts the process of glucose oxidation? FADH2 hexokinase NADPH ADP ATP
ATP
Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
ATP and NADPH
The light reactions of photosynthesis supply the Calvin cycle with
ATP and NADPH.
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.
In cells, what is usually the immediate source of energy for an endergonic reaction?
ATP, The hydrolysis of ATP provides the energy needed for an endergonic reaction.
What happens during the citric acid cycle?
Acetyl CoA enters the cycle one at a time and the cycle release NADH, FADH2, ATP, GTP, and CO2 as it returns the carbon compound to its original state. It takes 2 turns per molecule of glucose.
ATP
Adenosine triphosphate (ATP) is the high-energy form of adenosine because it contains the most phosphate groups (three). This molecule fuels many different endergonic (energy-requiring) enzymatic processes in biological organisms. ATP molecules diffuse or are transported to the place where the energy is needed and deliver chemical energy from the breaking of their phosphate bonds.
Catalyst
An enzyme is considered a catalyst because it speeds up chemical reactions without being used up.
Specific
An enzyme is considered specific because of its ability to recognize the shape of a particular molecule.
Denature
An enzyme is denatured when it loses its native conformation and its biological activity.
In an experiment with an enzyme, the 58th amino acid seems to form a covalent bond with a substrate molecule as part of the catalytic process. What would you say?
At some point the bond between the amino acid and the substrate must break. To work repeatedly, the enzyme must return to its original state at the end of each catalytic cycle. Some steps may form bonds or break bonds between the enzyme and substrate.
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.
High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of A) competitive inhibition. B) allosteric regulation. C) the specificity of enzymes for their substrates. D) an enzyme requiring a cofactor. E) positive feedback regulation.
B) allosteric regulation.
During intense exercise, as skeletal muscle cells go into anaerobiosis, the human body will increase its catabolism of A) fats only. B) carbohydrates only. C) proteins only. D) fats, carbohydrates, and proteins. E) fats and proteins only.
B) carbohydrates only.
Most CO₂ from catabolism is released during A) glycolysis. B) the citric acid cycle. C) lactate fermentation. D) electron transport. E) oxidative phosphorylation.
B) the citric acid cycle.
Where do the catabolic products of fatty acid breakdown enter into the citric acid cycle? A) pyruvate B) malate or fumarate C) acetyl CoA D) α-ketoglutarate E) succinyl CoA
C) acetyl CoA
Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule? A) the citric acid cycle B) the electron transport chain C) glycolysis D) synthesis of acetyl CoA from pyruvate E) reduction of pyruvate to lactate
C) glycolysis
Where are the proteins of the electron transport chain located? A) cytosol B) mitochondrial outer membrane C) mitochondrial inner membrane D) mitochondrial intermembrane space E) mitochondrial matrix
C) mitochondrial inner membrane
During aerobic respiration, H₂O is formed. Where does the oxygen atom for the formation of the water come from? A) carbon dioxide (CO₂) B) glucose (C₆H₁₂O₆) C) molecular oxygen (O₂) D) pyruvate (C₃H₃O₃-) E) lactate (C₃H₅O₃-)
C) molecular oxygen (O₂)
In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO₂, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A. Why is coenzyme A, a sulfur-containing molecule derived from a B vitamin, added? A) because sulfur is needed for the molecule to enter the mitochondrion B) in order to utilize this portion of a B vitamin which would otherwise be a waste product from another pathway C) to provide a relatively unstable molecule whose acetyl portion can be readily transferred to a compound in the citric acid cycle D) because it drives the reaction that regenerates NAD⁺ E) in order to remove one molecule of CO₂
C) to provide a relatively unstable molecule whose acetyl portion can be readily transferred to a compound in the citric acid cycle
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. -CO2 is reduced and O2 is oxidized. - O2 is reduced and CO2 is oxidized. -C6H12O6 is reduced and CO2 is oxidized. - O2 is oxidized and H2O is reduced.
C6H12O6 is oxidized and O2 is reduced.
A system at chemical equilibrium _____.
Can do no work
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.
Select the correct statement about cellular respiration. -Plants carry out cellular respiration only in organs such as roots that cannot carry out photosynthesis. - Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level. - Animals carry out cellular respiration whereas plants carry out photosynthesis.
Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level.
Anabolic pathways _____.
Consume energy to build up polymers from monomers
Where does glycolysis take place in eukaryotic cells? A) mitochondrial matrix B) mitochondrial outer membrane C) mitochondrial inner membrane D) mitochondrial intermembrane space E) cytosol
Cytosol
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the A) oxidation of glucose and other organic compounds. B) flow of electrons down the electron transport chain. C) affinity of oxygen for electrons. D) H⁺ concentration across the membrane holding ATP synthase. E) transfer of phosphate to ADP.
D) H⁺ concentration across the membrane holding ATP synthase.
Where is ATP synthase located in the mitochondrion? A) cytosol B) electron transport chain C) outer membrane D) inner membrane E) mitochondrial matrix
D) inner membrane
Inside an active mitochondrion, most electrons follow which pathway? A) glycolysis → NADH → oxidative phosphorylation → ATP → oxygen B) citric acid cycle → FADH₂ → electron transport chain → ATP C) electron transport chain → citric acid cycle → ATP → oxygen D) pyruvate → citric acid cycle → ATP → NADH → oxygen E) citric acid cycle → NADH → electron transport chain → oxygen
E) citric acid cycle → NADH → electron transport chain → oxygen
During cellular respiration, acetyl CoA accumulates in which location? A) cytosol B) mitochondrial outer membrane C) mitochondrial inner membrane D) mitochondrial intermembrane space E) mitochondrial matrix
E) mitochondrial matrix
The reaction ADP + P --> ATP is a(n) _____ reaction.
Endergonic, Energy has been acquired from the surroundings.
Which of these reactions requires a net input of energy from its surroundings?
Endergonic, The products of endergonic reactions have more potential energy than the reactants.
Which of the following is a statement of the first law of thermodynamics?
Energy cannot be created or destroyed.
Enzymes speed reactions mainly by ...
Enzymes always lower EA, though they may have other effects as well. With a lower EA, more collisions can produce the transition state.
Which of the following is true of enzymes?
Enzymes increase the rate of chemical reaction by lowering activation energy barriers.
Fact about enzymes.
Enzymes may give and take atoms and form temporary covalent bonds with substrates as they catalyze reactions.
Enzymes work by _____.
Enzymes work by reducing the energy of activation (lowering the Ea)
The following reaction A --> B + C + heat is a(n) _____ reaction.
Exergonic, Energy has been released.
A(n) _____ reaction occurs spontaneously.
Exergonic, in exergonic reactions the products have less potential energy than the reactants. Kinetic energy is the energy of motion.
The energy for an endergonic reaction comes from a(n) _____ reaction.
Exergonic, the energy released by an exergonic reaction can be used to drive an endergonic reaction. This is an endergonic reaction.
Which of these is NOT a product of glycolysis? NADH pyruvate ATP FADH2
FADH2
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
In the combined processes of glycolysis and cellular respiration, what is consumed and what is produced? -ATP is consumed, and oxygen is produced. - Glucose is consumed, and carbon dioxide is produced. - Oxygen is consumed, and glucose is produced. - Water is consumed, and ATP is produced. - Carbon dioxide is consumed, and water is produced.
Glucose is consumed, and carbon dioxide is produced.
What is fermentation?
Glycolysis and then the regeneration of NAD+. It comes in the forms of alcohol fermentation and lactic acid fermentation. It does not need any oxygen or an electron transport chain.
Which statement best supports the hypothesis that glycolysis is an ancient metabolic pathway that originated before the last universal common ancestor of life on Earth? -Glycolysis neither uses nor needs O2. Glycolysis is found in all eukaryotic cells. - Ancient prokaryotic cells, the most primitive of cells, made extensive use of glycolysis long before oxygen was present in Earth's atmosphere. - Glycolysis is widespread and is found in the domains Bacteria, Archaea, and Eukarya. - The enzymes of glycolysis are found in the cytosol rather than in a membrane-enclosed organelle.
Glycolysis is widespread and is found in the domains Bacteria, Archaea, and Eukarya.
Which fact is most important in explaining how enzymes speed reactions?
High-energy collisions are less common than low-energy collisions. Enzymes provide reaction pathways that have low activation energy requirements. This allows low-energy collisions to cause reactions.
Substrate
In a catalyzed reaction a reactant is often called a substrate.
Where do pyruvate acetylation and the citric acid cycle happen?
In the mitochondria
What are the inputs and outputs of fermentation?
Input - glycolysis - glucose, 2 ATP, 2 NAD+, 4 ADP, 4Pi fermentation - 2 pyruvate, 2 NADH Outputs - 2 ATP, 2 NAD+, and 2 ethanol & 2 CO2 OR 2 lactate
What are the inputs and outputs of oxidative phosphorylation?
Inputs - 10 NADH, 2 FADH2, H+, O2 Outputs - H2O, 28 ATP (max)
What are the inputs and outputs of pyruvate acetylation and the citric acid cycle per molecule of glucose?
Inputs - 2 pyruvate, 2 oxaloacetate Outputs - 6 CO2, 8 NADH, 2 FADH2, 2 ATP Citric Acid Cycle Outputs per turn - 2 CO2, 3 NADH, 1 FADH2, 1 ATP
What are the inputs and outputs of glycolysis?
Inputs - glucose, 2 ATP, 2 NAD+, 4 ADP, 4Pi Outputs - 2 pyruvate, 2 H2O, 4 ATP, 2 NADH, 2 H+ Net Output - 2 pyruvate, 2 H2O, 2 ATP, 2 NADH, 2 H+
An enzyme _____.
Is an organic catalyst. Enzymes are proteins that behave as catalysts.
As a result of its involvement in a reaction, an enzyme _____.
Is unchanged. Enzymes are not changed as a result of their participation in a reaction.
What is the fate of the phosphate group that is removed when ATP is converted to ADP?
It is acquired by a reactant in an endergonic reaction. By acquiring the phosphate group the reactant acquires energy.
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? -It was lost as heat. - It is stored in the carbon dioxide and water molecules released by these processes. - It is stored in NADH and FADH2 - It is stored in pyruvate. - It is stored in the ATP that was formed by glycolysis and the citric acid cycle.
It is stored in NADH and FADH2
Which of the following describes the process of glycolysis? - Glycolysis occurs in the mitochondria. - It represents the first stage in the chemical oxidation of glucose by a cell. - It converts one glucose molecule to two molecules of pyruvate and carbon dioxide. - Glycolysis produces 30 ATP from each molecule of glucose. - It requires ATP and NADH.
It represents the first stage in the chemical oxidation of glucose by a cell.
How does the cell make ATP from the energy released by the electron transport chain?
It uses chemiosmosis. As the electrons pass down the electron transport chain, it moves H+'s into the intermembrane space to create a concentration gradient. ATP synthase lets the H+'s flow back into the mitochondrial matrix, but as they go through it they turn its rotor providing the energy needed to phosphorylate ATP.
Which of the following is true of metabolism in its entirety in all organisms?
Metabolism consists of all the energy transformation reactions in an organism.
What happens in during the electron transport chain?
NADH and FADH2 drop off their electrons to the top of the electron transport chain. The electron carriers along the chain alternate between oxidized and reduced as they pass and receive electrons. Finally the electron reaches the end and it get passed to an oxygen. 2 H+ molecules bind to the oxygen as well and it is released as water. No ATP is made directly by the ETC. It pumps H+ molecules out of the mitochondrial matrix into the intermembrane space.
After 3-PGA is phosphorylated, it is reduced by _____.
NADPH
Which of the following molecules is the primary product of photosystem I?
NADPH
Which of the following products of the light reactions of photosynthesis is consumed during the Calvin cycle?
NADPH
Photorespiration occurs when rubisco reacts RuBP with
O2.
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.
Oxidation vs. Reduction
Oxidation is the loss of electrons by a substance Reduction is the gain of electrons by a substance (it REDUCES the charge)
What happens between glycolysis and the citric acid cycle?
Oxidation of pyruvate into Acetyl CoA
What are redox reactions?
Oxidation reduction reactions - the transfer of electrons from one substance to another.
What is one of the strongest oxidizing agents? Why?
Oxygen because it is so electronegative
Which term describes ATP production resulting from the capture of light energy by chlorophyll?
Photophosphorylation
Which process produces oxygen?
Photosynthesis
Which property is necessary for protein A to bind to protein B?
Protein A must have regions of shape and charge that are complementary to those on Protein B. -Molecular shape determines how biological molecules recognize and respond to one another with specificity. Biological molecules often bind temporarily to each other by forming weak interactions, but only if their shapes are complementary, and if their functional groups and surface charges are compatible. The role of molecular shape illustrates how biological organization leads to a match between structure and function, one of biology's unifying themes.
In general, enzymes are what kinds of molecules?
Proteins
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
_____ has a longer wavelength than _____.
Red ... green
Reducing agent vs Oxidizing agent
Reducing agent - the electron donor in a redox reaction Oxidizing agent - the electron acceptor in a redox reaction
Which of the following reactions ensures that the Calvin cycle can make a continuous supply of glucose?
Regneration of RuBP
Carbon fixation involves the addition of carbon dioxide to _____.
RuBP
Where does the Calvin cycle occur?
Stroma
What name is given to the reactants in an enzymatically catalyzed reaction?
Substrate. This is the name given to the reactants in an enzymatically catalyzed reaction
Most cells cannot harness heat to perform work because _____.
Temperature is usually uniform throughout a cell
What else is the citric acid cycle called?
The Krebs Cycle
How can "induced fit" influence the specificity of an enzyme?
The active site of the enzyme will change shape to make a better fit with only the appropriate substrate, which can bring the reactive portion of the enzyme closer to the substrate.
In cellular respiration, a series of molecules forming an electron transport chain alternately accepts and then donates electrons. What is the advantage of such an electron transport chain? -The advantage of an electron transport chain is that a small amount of energy is released with the transfer of an electron between each pair of intermediates. - The advantage of the respiratory electron transport chain is that oxygen is the final electron acceptor. - The advantage of an electron transport chain is the production of a large number of reduced, high-energy intermediates.
The advantage of an electron transport chain is that a small amount of energy is released with the transfer of an electron between each pair of intermediates.
Identify all correct statements about the basic function of fermentation. - The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis. - The basic function of fermentation is the production of additional ATP by further oxidation of the products of glycolysis. - The basic function of fermentation is the production of ethyl alcohol or lactic acid.
The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis.
Which of the following is true when comparing an uncatalyzed reaction to the same reaction with a catalyst?
The catalyzed reaction will have the same G
Which of the following statements about the chemiosmotic synthesis of ATP is correct? -The energy for production of ATP from ADP comes directly from a gradient of electrons across the inner mitochondrial membrane. - Oxygen participates directly in the reaction that makes ATP from ADP and P. - The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane. - The chemiosmotic synthesis of ATP occurs only in eukaryotic cells, because it occurs in mitochondria. - Chemiosmotic ATP synthesis requires oxygen.
The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane.
Where does glycolysis take place?
The cytoplasm
Which statement describes the functioning of photosystem II?
The electron vacancies in P680+ are filled by electrons derived from water.
Energy activation
The energy of activation must be overcome in order for a reaction to proceed.
Which of the following statements accurately describes the function of a metabolic pathway involved in cellular respiration? -The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP. - The function of the bonding of acetic acid to the carrier molecule CoA to form acetyl CoA is the reduction of glucose to acetyl CoA. - The function of the citric acid cycle is the transfer of electrons from pyruvate to NADH to O2.
The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP.
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.
Which statement about the citric acid cycle is correct? - The citric acid cycle depends on the availability of NAD+, which is a product of glycolysis. - The oxidation of compounds by the citric acid cycle requires molecular oxygen. - The citric acid cycle produces most of the ATP that is subsequently used by the electron transport chain. - The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle. - The citric acid cycle oxidizes glucose to carbon dioxide.
The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.
Which set of reactions uses H2O and produces O2?
The light-dependent reactions
Which of the following statements best describes the relationship between the light-dependent and light-independent reactions of photosynthesis?
The light-dependent reactions produce ATP and NADPH, which are then used by the light-independent reactions.
What is the importance of the light-independent reactions in terms of carbon flow in the biosphere?
The light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars.
Which of the following provides molecular evidence that signal transduction pathways evolved early in the history of life?
The molecular details of cell signaling are quite similar in organisms whose last common ancestor was a billion years ago. - Yeast and mammal cells, for example, are very distantly related yet share many similarities in cell signaling.
You have isolated a previously unstudied protein, identified its complete structure in detail, and determined that it is an enzyme that catalyzes the breakdown of a large substrate. You notice it has two binding sites: one large and one small. Speculate about how this enzyme might function.
The small site is probably a binding site for a small molecule whose binding affects the enzyme's shape and function—its breakdown of the large substrate. -Allosteric regulation is the term used to describe any case in which a protein's function at one site is affected by the binding of a small regulatory molecule to a separate site. In the simplest kind of allosteric regulation, an activating or inhibiting regulatory molecule binds to a regulatory site (sometimes called an allosteric site). The binding of an activator to a regulatory site stabilizes the shape that has functional active sites, whereas the binding of an inhibitor stabilizes the inactive form of the enzyme.
How does the breaking down of sugars release energy?
The transfer of electrons during chemical reactions releases stored energy which is used to synthesize ATP. Redox reactions
What is energy coupling?
The use of energy released from an exergonic reaction to drive an endergonic reaction.
Which statement is true of enzymes?
There are many copies of each enzyme; they're usually proteins but sometimes they are RNA; and they only attack substrates that fit the shape and charge of the active site.
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.
What is the biological significance of the light-independent reactions of photosynthesis?
They convert carbon dioxide to sugar.
Plants are photoautotrophs. What does this mean?
They use light energy to drive the synthesis of organic molecules from inorganic materials.
True or false? The light-dependent reactions of photosynthesis use water and produce oxygen.
True
Complex
When properly aligned, the enzyme and substrate form an enzyme-substrate (ES)complex
Which of these is exhibiting kinetic energy?
a space station orbiting Earth
In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO2, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A. These three steps result in the formation of -acetyl CoA, O2, and ATP. - acetyl CoA, NADH, H+, and CO2. -acetyl CoA, FAD, O2, and CO2. - acetyl CoA, NAD+, ATP, and CO2. - acetyl CoA, FADH2, and CO2.
acetyl CoA, NADH, H+, and CO2.
To what does the term "ligand" refer in cell biology?
any small molecule that can bind in a specific manner to a larger one -Ligands are the small signaling molecules that bind specifically to corresponding protein-receptor molecules.
In any ecosystem, terrestrial or aquatic, what group(s) is (are) always necessary?
autotrophs
receptor tyrosine kinases
binding of the signaling molecule forms a dimer, catalyzes the transfer of a phosphate group to the receptor
Generation of proton gradients across membranes occurs during
both photosynthesis and respiration.
Which of the following are among the most common second messengers?
calcium ion and cAMP
Compared to C3 plants, C4 plants
can continue to fix CO2 even at relatively low CO2 concentrations and high oxygen concentrations.
In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?
cellular respiration
The photosynthetic membranes are found in the _____ in plant cells.
chloroplasts
In C4 and CAM plants carbon dioxide is fixed in the _____ of mesophyll cells.
cytoplasm
The hormone epinephrine causes opposite effects in two populations of target cells because _____.
each set of target cells has different receptor-transduction mechanisms -Look at the epinephrine example in your text. That hormone can trigger different responses in different target cells. Epinephrine can trigger vasodilation responses (blood vessels in skeletal muscles used for fight-or-flight) and vasoconstriction responses (gut vasculature) in an emergency that evokes its secretion.
"Conservation of energy" refers to the fact that _____.
energy cannot be created or destroyed but can be converted from one form to another
What is the function of tyrosine-kinase receptors?
enzymatic phosphorylation of tyrosine in the receptor protein -Phosphorylated tyrosine-kinase receptors then interact with relay proteins within the cell.
Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _____ is to _____.
exergonic; endergonic
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.
During aerobic respiration, electrons travel downhill in which sequence? -glucose → pyruvate → ATP → oxygen - food → glycolysis → citric acid cycle → NADH → ATP - food → citric acid cycle → ATP → NAD+ -food → NADH → electron transport chain → oxygen - glucose → ATP → electron transport chain → NADH
food → NADH → electron transport chain → oxygen
A molecule that is phosphorylated -has been oxidized as a result of a redox reaction involving the gain of an inorganic phosphate. - has a decreased chemical reactivity; it is less likely to provide energy for cellular work. - has less energy than before its phosphorylation and therefore less energy for cellular work. - has an increased chemical potential energy; it is primed to do cellular work. - has been reduced as a result of a redox reaction involving the loss of an inorganic phosphate.
has an increased chemical potential energy; it is primed to do cellular work.
Which of these are by-products of cellular respiration?
heat, carbon dioxide, and water
What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?
hydrolysis
Even though plants cells photosynthesize, they still use their mitochondria for oxidation of pyruvate. When and where will this occur? - in all cells all the time in photosynthesizing cells -in the light and in other tissues in the dark - in nonphotosynthesizing cells only - in photosynthetic cells in the light, while photosynthesis occurs concurrently - in cells that are storing glucose only
in all cells all the time
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 of ATP in a cell would be expected to -activate the enzyme and increase the rates of glycolysis and the citric acid cycle. - inhibit the enzyme and thus increase the rate of glycolysis and the concentration of citrate. - inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle. - activate the enzyme and thus slow the rates of glycolysis and the citric acid cycle. - inhibit the enzyme and thus increase the rates of glycolysis and the citric acid cycle.
inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle.
G protein-coupled receptors
interact directly with G proteins
How will a healthy individual's ATP production change during an eight-hour fast?
it won't change significantly
In muscle cells, fermentation produces _____. - pyruvate - carbon dioxide, ethanol, NADH, and ATP - carbon dioxide, ethanol, and NAD+ - lactate, NADH, and ATP - lactate and NAD+
lactate and NAD+
The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction - loses electrons and gains potential energy. - neither gains nor loses electrons, but gains or -loses potential energy. gains electrons and loses potential energy. - loses electrons and loses potential energy. -gains electrons and gains potential energy.
loses electrons and loses potential energy.
The overall function of the Calvin cycle is _____.
making sugar
The splitting of carbon dioxide to form oxygen gas and carbon compounds occurs during
neither photosynthesis nor respiration
Carbon dioxide (CO2) is released during which of the following stages of cellular respiration? - oxidative phosphorylation and fermentation - oxidation of pyruvate to acetyl CoA and the citric acid cycle - fermentation and glycolysis - glycolysis and the oxidation of pyruvate to acetyl CoA - the citric acid cycle and oxidative phosphorylation
oxidation of pyruvate to acetyl CoA and the citric acid cycle
One function of both alcohol fermentation and lactic acid fermentation is to - oxidize NADH to NAD+. - reduce FADH2 to FAD+. - reduce NAD+ to NADH. - reduce FAD+ to FADH2. -do none of the above.
oxidize NADH to NAD+.
Photosynthesis is a redox reaction. This means that H2O is _____ during the light reactions and CO2 is _____ during the Calvin cycle.
oxidized...reduced
Which of the following is a product of the light reactions of photosynthesis?
oxygen, ATP, and NADPH
In C3 plants the conservation of water promotes _____.
photorespiration
Chemical energy is a form of _____ energy.
potential
In fermentation _____ is reduced and _____ is oxidized. pyruvate ... NADH lactate ... NADH NAD+ ... pyruvate lactate ... ethanol NADH ... lactate
pyruvate ... NADH
Which of the following does not occur during the Calvin cycle?
release of oxygen
Which process is most directly driven by light energy?
removal of electrons from chlorophyll molecules
When oxygen is released as a result of photosynthesis, it is a direct by-product of
splitting water molecules.
Where does the Calvin cycle take place?
stroma of the chloroplast
In glycolysis, ATP molecules are produced by _____.
substrate level phosphorylation
The ATP made during glycolysis is generated by - chemiosmosis. - photophosphorylation. - oxidation of NADH to NAD+. - substrate-level phosphorylation. - electron transport.
substrate-level phosphorylation.
The ultimate source of energy to support most life on Earth is _____.
sunlight
Catabolism
the breaking down of high-energy molecules into simple molecules, generates ATP
Anabolism
the building of complex molecules from simple ones, requires ATP
What is proton-motive force? - the force provided by a transmembrane hydrogen ion gradient -the force that moves hydrogen to NAD+ -the force that moves hydrogen into the intermembrane space -the force that moves hydrogen into the mitochondrion -the force required to remove an electron from hydrogen
the force provided by a transmembrane hydrogen ion gradient
In mitochondria, chemiosmosis translocates protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis translocates protons from
the stroma to the thylakoid space.
The phrase gene expression refers to the control of
the synthesis of the product of a specific gene -If you had trouble with this question, review the following material: Genes control protein production indirectly, using a related molecule called RNA as an intermediary. The sequence of nucleotides along a gene is transcribed into RNA, which is then translated into a protein with a unique shape and function. The process by which the information in a gene directs the manufacture of a cellular product is called gene expression.
Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions?
the terminal phosphate
C4 plants occur more commonly in desert conditions because _____.
they can fix carbon at the lower CO2 concentrations that develop when the stomata are closed
C4 plants differ from C3 and CAM plants in that C4 plants _____.
transfer fixed carbon dioxide to cells in which the Calvin cycle occurs
Which of the following best describes the main purpose of the combined processes of glycolysis and cellular respiration? -producing complex molecules from chemical building blocks - the breakdown of glucose to carbon dioxide and water - transforming the energy in glucose and related molecules in a chemical form that cells can use for work - breaking down ATP, so that ADP and P can be reused - catabolism of sugars and related compounds
transforming the energy in glucose and related molecules in a chemical form that cells can use for work
In the electromagnetic spectrum, the type of radiation that we call visible light occurs between _____.
ultraviolet radiation and infrared radiation
The electrons stripped from glucose in cellular respiration end up in which compound? ATP water oxygen NADH carbon dioxide
water
The light reactions of photosynthesis use _____ and produce _____.
water ... NADPH
The mathematical expression for the change in free energy of a system is ΔG =ΔH - TΔS. Which of the following is (are) correct?
ΔG is the change in free energy.