Exam 1 Cell Bio (3,13,14)

In eukaryotic cells, what is the final electron acceptor in the electron transport chain? NAD+ O2 ATP CO2 FADH2

O2

Where does the oxidative (oxygen-dependent) stage of the breakdown of food molecules occur in a eukaryotic cell? endoplasmic reticulum cytosol mitochondrion Golgi apparatus

mitochondrion

(Q009) If the products of a reaction have more free energy than the reactants, then that reaction is spontaneous. energetically favorable. not energetically favorable. physically impossible.

not energetically favorable.

(Q001) Which of the following correctly matches the cellular location with the production of ATP by oxidative phosphorylation in that cell type? chloroplasts—plants mitochondria—archaea cell wall—photosynthetic algae plasma membrane—bacteria

plasma membrane—bacteria

When protons move down their electrochemical gradient into the mitochondrial matrix, what do they do? produce NAD+ produce NADH consume ATP produce ATP move electrons through the respiratory chain

produce ATP

(Q010) What is the value of ΔG at equilibrium? zero positive negative It depends on the concentration of substrates and products.

zero

(Q012) The proton flow through the transmembrane H+ carrier of ATP synthase results in bending of the carrier and stalk to produce mechanical force. moving ADP and Pi across the membrane into the enzyme active site. mechanical rotation that is converted into the chemical-bond energy of ATP. binding of the proton to ADP to enhance formation of the phosphate bond.

mechanical rotation that is converted into the chemical-bond energy of ATP.

Stage 1 of photosynthesis is, in large part, equivalent to what process? the citric acid cycle glycolysis the carbon-fixation cycle oxidative phosphorylation the production of acetyl CoA by the pyruvate dehydrogenase complex

oxidative phosphorylation

(Q006) The first step of glycolysis uses one ATP molecule in order to transport glucose. phosphorylate glucose. breakdown sucrose. store glucose.

phosphorylate glucose.

(Q013) How is pyruvate imported into the mitochondrial matrix for use in the citric acid cycle? proton gradient-driven symport sodium gradient-driven antiport ATP-driven pyruvate pump diffusion through porin complexes in the membrane

proton gradient-driven symport

The movement of electrons through the electron-transport chain in mitochondria does which of the following? pumps ATP across the inner mitochondrial membrane pumps protons out of the mitochondrial matrix consumes ATP produces NADH produces oxygen

pumps protons out of the mitochondrial matrix

(Q005) In an enzymatic reaction, a molecule gains an electron. This is known as a(n) ___________ reaction. reduction oxidation hydrogenation electronegative

reduction

(Q022) Chlorophyll appears green because it absorbs blue light. absorbs red light. reflects green light. reflects UV light.

reflects green light.

(Q018) Gluconeogenesis requires a total of ___________ ATP and GTP molecules combined. two four six eight

six

When nutrients are plentiful, plants can store glucose as what? fats glucose 6-phosphate glycogen and starch starch glycogen

starch

(Q009) Refer to the diagram below. If cells that cannot carry out fermentation were grown in anaerobic conditions, at which step would glycolysis halt? step 6: where NAD+ is converted to NADH step 1: using ATP to phosphorylate glucose step 10: production of pyruvate step 4: the cleavage of the 6-carbon molecule into two 3-carbon molecules

step 6: where NAD+ is converted to NADH **no fermentation= no NAD+ production

(Q016) In addition to being converted to acetyl CoA for the citric acid cycle, pyruvate made during glycolysis can be used for membrane transport. synthesis of alanine. fermentation. synthesis of alanine and fermentation.

synthesis of alanine and fermentation.

(Q014) The low redox potential of NADH means that it has a tendency to give up electrons. low free energy. high electron affinity. very stable bond.

tendency to give up electrons.

What occurs in the first step of the citric acid cycle? CO2 is released. A two-carbon molecule is combined with a four-carbon molecule to form citrate. ATP is consumed. NADH is produced. Two molecules of acetyl CoA combine to form oxaloacetate.

A two-carbon molecule is combined with a four-carbon molecule to form citrate.

Which of the following statements are true of electron transfer in the electron-transport chain? Choose one or more: A.Each electron transfer is an oxidation-reduction reaction. B.NADH is a strong electron donor. C.When an electron carrier accepts an electron, it becomes oxidized. D.NADH has a relatively high electron affinity and initiates the electron-transport process. E.Electrons move toward molecules with a high redox potential.

A.Each electron transfer is an oxidation-reduction reaction. B.NADH is a strong electron donor. E.Electrons move toward molecules with a high redox potential.

(Q019) In the presence of high levels of ___________, the enzyme phosphofructokinase is inhibited. glucose ADP fructose ATP

ATP *phosphofructokinase phosphorylates. High ATP stops it because then more ATP production through glycolysis is unnecessary

Most of the energy released by oxidizing glucose is saved in the high-energy bonds of what molecules? H2O and CO2 ATP and other activated carriers O2 GDP and other activated carriers ADP and other activated carriers

ATP and other activated carriers

(Q021) Stage two of photosynthesis (or the light-independent reactions) uses which input molecules to produce organic food molecules? ATP, NADPH, CO2 O2, NADH, ADP H2O, light, chlorophyll amino acids, sugars, fatty acids

ATP, NADPH, CO2

What is true of the breakdown of polymers inside living cells? A. It occurs without the need for enzymes. B. It is associated with a negative change in free energy. C. It is energetically unfavorable.

B. It is associated with a negative change in free energy.

Which of these processes require a membrane? Choose one or more: generation of ATP by glycolysis generation of ATP by photosynthesis in plants generation of ATP by photosynthesis in bacteria generation of energy by mitochondria generation of ATP by oxidative phosphorylation

generation of ATP by photosynthesis in plants generation of ATP by photosynthesis in bacteria generation of energy by mitochondria generation of ATP by oxidative phosphorylation *Correct. The generation of ATP by oxidative phosphorylation differs from the way ATP is produced during glycolysis in that it requires a membrane-bound compartment, such as mitochondria. A related membrane-based process produces ATP during photosynthesis in plants and photosynthetic bacteria.

(Q001) The food molecule whose breakdown generates most of the energy for a majority of animal cells is sucrose. glucose. fat. protein.

glucose *glucose is main energy source for animals

(Q010) The energies of phosphate bonds for different molecules in glycolysis are shown. Based on this graphic, the transfer of a phosphate from which of the molecules to ADP (to form ATP) is energetically UNFAVORABLE? phosphoenolpyruvate 1,3-bisphosphoglycerate glucose 6-phosphate They are all energetically favorable.

glucose 6-phosphate

(Q020) Glycogen synthetase enzyme, which forms glycogen from glucose, is activated by excess ATP. glucose 6-phosphate. phosphate. pyruvate.

glucose 6-phosphate. **glycogen is stored glucose, too much G6P means that its overproduced meaning it should go back to glucose to be stored

When food is plentiful, animals can store glucose as what? glucose 6-phosphate glycogen starch acetyl CoA glycogen or starch

glycogen *Glycogen and starch are both branched polysaccharides made of glucose, but only glycogen is made by animal cells. Starch is made by plants

Useful energy is obtained by cells when sugars derived from food are broken down by which processes? glycolysis, the citric acid cycle, and oxidative phosphorylation glycolysis, the Calvin cycle, and oxidative phosphorylation glycolysis, the citric acid cycle, and gluconeogenesis gluconeogenesis, the citric acid cycle, and oxidative phosphorylation gluconeogenesis, fermentation, and oxidative phosphorylation

glycolysis, the citric acid cycle, and oxidative phosphorylation

(Q003) Individuals with inherited diseases causing mitochondrial dysfunction typically experience which of the following symptoms? heart problems sterilit bone deformities light sensitivity

heart problems

(Q002) Living systems can generate and maintain order without violating the second law of thermodynamics because they generate heat. order. decreased entropy. macromolecules.

heat *not decreased entropy **disorder is still created by releasing energy in the form of heat.

(Q007) If a reaction is energetically favorable (exergonic), then it must produce a(n) increase in entropy. decrease in heat. increase in activation energy. decrease in reaction time.

increase in entropy.

(Q010) Protons are pumped across the mitochondrial inner membrane to accumulate in the mitochondrial matrix. intermembrane space. cytosol. electron-transport chain.

intermembrane space.

(Q007) What is the fermentation product produced in an anaerobic muscle cell? ethanol lactic acid 1 ATP 1 ADP

lactic acid

(Q016) The cytochrome complexes contain heme prosthetic groups, which have a higher redox potential than the iron-sulfur centers found in other electron-transport chain complexes like NADH dehydrogenase. Where in the electron-transport chain would the cytochrome complexes thus be located relative to iron-sulfur center complexes? later in the chain earlier in the chain It cannot be determined. at the same point of the chain

later in the chain

(Q008) Enzymes increase the speed of a chemical reaction because they increase the temperature to provide the necessary boost of energy. lower the activation energy needed to start the reaction. make the reaction more energetically favorable. make the reaction spontaneous.

lower the activation energy needed to start the reaction.

(Q002) Glycolysis alone captures approximately what percentage of the free energy available in a molecule of glucose? 10% 20% 50% 99%

10%

(Q015) The number of ATP molecules that could be synthesized from the energy released by the transfer of two electrons from NADH to molecular oxygen is 2.5. 4. 3. 1.5.

2.5.

(Q005) Shown is the structure of a mitochondrion with different compartments labeled. Which of the numbers represents the most permeable membrane of the mitochondrion?

3. outer membrane

(Q016) In the following condensation reaction, how does ATP power the formation of product A-B? A phosphate is first transferred to reactant A−OH to form a high energy intermediate. A phosphate is first transferred to reactant B−H to form a high energy intermediate. ATP is split into free phosphate and the energy is released as heat. ADP binds to reactant A−OH and releases inorganic phosphate.

A phosphate is first transferred to reactant A−OH to form a high energy intermediate. *PHOSPHATE TRANFERRED TO REACTANT W/ -OH

(Q011) The pH of the mitochondrial matrix is ___________, which is ___________ than that of the intermembrane space. 7.9; higher 7.2; lower 7.2; higher 7.9; lower

7.9; higher

Which statement is true about the removal of a terminal phosphate from ATP? A. The reaction is energetically favorable. B. The reaction is a condensation reaction. C. The reaction is associated with a positive change in ΔG°.

A. The reaction is energetically favorable.

Which part of the mitochondrion contains the proteins that carry out oxidative phosphorylation?

B

Which activated carrier contains a high-energy bond whose hydrolysis releases a large amount of free energy? A. water B. ATP C. NADH D. glucose E. high-energy electrons

B. ATP

Which of the following best describes this reaction? A. hydrolysis B. condensation C. redox

B. condensation **In the reaction shown, water is removed, which signals condensation.

The first living cells on Earth—whether prokaryotes or primitive eukaryotes—most likely generated ATP by what process? A. oxidative phosphorylation B. fermentation C. photosynthesis D. aerobic cell respiration E. nitrogen fixation

B. fermentation *Not nitrogen fixation. Nitrogen fixation is a process for producing nitrogen-containing organic molecules such as amino acids; like carbon fixation, it consumes energy, rather than producing it.

Small molecules diffuse through the cytosol very efficiently by doing which of the following? A. forming noncovalent bonds with other molecules B. moving randomly, knocked around by colliding with other molecules C. migrating along cytoskeletal microtubules D. binding to larger molecules E. taking the shortest path from one location to another

B. moving randomly, knocked around by colliding with other molecules

The ethanol in wine and beer is produced from metabolic reactions carried out by the yeast Saccharomyces cerevisiae. Since it is of great commercial value, researchers have studied factors that influence ethanol production. To maximize ethanol yield, which environmental factor should be limiting? A. sunlight B. oxygen C. glucose D. carbon dioxide

B. oxygen

In a cell, the rate at which an enzyme will encounter its substrate depends on which of the following? A. the concentration of other proteins in the cytosol B. the concentration of the substrate C. the size of the enzyme D. the way that the cytosol is structured

B. the concentration of the substrate

(Q013) For the following uncatalyzed reaction at equilibrium, how would the reaction change if it was now an enzyme-catalyzed reaction at equilibrium? Levels of X would increase. Levels of Y would increase. Nothing would occur, since the reaction is at equilibrium. Both forward and reverse reaction rates would increase.

Both forward and reverse reaction rates would increase.

All four possible reactions in the animation are energetically favorable; the energy of the four products is lower than the energy of the original starting molecule. Why does the starting molecule not completely and quickly convert to its possible products before the addition of heat or an enzyme? A. The starting molecule can only form some of the products quickly. B. The starting substrate does quickly convert to the four products. C. An activation energy barrier exists that must be overcome for conversion to products. D. When heat was added to the reaction, only some of the products were produced.

C. An activation energy barrier exists that must be overcome for conversion to products.

Which of the following statements regarding NADPH and NADH is true? A. NADH carries electrons in animal cells and NADPH does the same in plants. B. NADPH loses a phosphate group to form NADH during biosynthetic reactions. C. NADPH and NADH are used in separate biochemical pathways in cells. D. NADPH and NADH deliver electrons to the same set of enzymes.

C. NADPH and NADH are used in separate biochemical pathways in cells. **REVIEW NADPH and NADH are used in independent pathways in cells. NADPH operates chiefly during biosynthetic reactions, while NADH plays a critical role in the catabolism of food molecules.

Which of the following statements about NADPH and/or NADH is not true? A. NADPH is an activated carrier molecule that is usually used in biosynthetic reactions to build energy-rich molecules. B. NADH is an activated carrier molecule that is usually used in oxidation reactions to produce ATP. C. NADPH is an activated carrier molecule that is used primarily by plants. D. All of these statements are incorrect regarding the activated carrier nature of these molecules.

C. NADPH is an activated carrier molecule that is used primarily by plants. **REVIEW, got wrong 3 times NADPH is an activated carrier molecule that is used throughout the evolutionary tree of life, including but certainly not limited to plants. Animal cells also regularly use the NADPH/NADP+ cycle.

In thermodynamics, what does the term "free energy" refer to? A. energy that cannot be harnessed to do work or drive chemical reactions B. excess energy from a reaction that a cell does not use C. energy that can be harnessed to do work or drive chemical reactions D. energy required to initiate a chemical reaction E. energy that cells borrow from the environment

C. energy that can be harnessed to do work or drive chemical reactions

(Q003) The major products of the citric acid cycle are pyruvate and ATP. CO2 and NADH. H2O and ATP. NADH and ATP.

CO2 and NADH.

(Q013) Each molecule of acetyl-CoA entering the citric acid cycle produces two ___________ and four ___________. NADH; ATP CO2; activated carriers ATP; GTP activated carriers; H2O

CO2; activated carriers

Which statement about enzymes is not true? A. Enzymes reduce the activation energy required to initiate a spontaneous reaction. B. Enzymes can speed up energetically favorable reactions. C. Enzymes can help build large polymers. D. An enzyme can force an energetically unfavorable reaction to take place inside the cell.

D. An enzyme can force an energetically unfavorable reaction to take place inside the cell. **Wrong 1st time Enzymes can couple energetically unfavorable reactions with energetically favorable ones, but they cannot make energetically unfavorable reactions take place without such coupling.

Compared to adding heat to the system, what is the advantage of using an enzyme to overcome an energy barrier? A. An enzyme generates multiple different products using multiple pathways. B. An enzyme speeds up a reaction more than heat does. C. An enzyme can catalyze a reaction in many different ways. D. An enzyme is specific for one desired pathway and end product.

D. An enzyme is specific for one desired pathway and end product.

Which statement about polymers is true? A. Polymer breakdown requires an input of free energy and involves the release of water. B. Polymer synthesis requires an input of free energy and involves the consumption of water. C. Polymer breakdown requires an input of free energy and involves the consumption of water. D. Polymer synthesis requires an input of free energy and involves the release of water.

D. Polymer synthesis requires an input of free energy and involves the release of water. **REVIEW In cells, polymers are synthesized by condensation reactions, which require energy and the release of water. This is the opposite of a hydrolysis reaction, which consumes water.

Which energy conversion characterizes photosynthesis? A. electromagnetic (light) energy → kinetic energy B. electromagnetic (light) energy → heat energy C. electromagnetic (light) energy → CO2 D. electromagnetic (light) energy → chemical bond energy E. electromagnetic (light) energy → oxidation energy

D. electromagnetic (light) energy → chemical bond energy **After 2 wrong attempts

What is the measure of disorder in a system called? A. free energy B. second law of thermodynamics C. catabolism D. entropy E. enthalpy

D. entropy

Which of the following does not describe an oxidation reaction? A. the removal of electrons from a molecule B. the conversion of Fe2+ to Fe3+ C. the addition of oxygen atoms to a molecule D. the conversion of a chlorine atom to Cl-

D. the conversion of a chlorine atom to Cl- *oxidation is losing, Cl is gaining here

Which of the following does not occur in cells? A. the conversion of sunlight into energy stored in chemical bonds during photosynthesis B. the metabolism of nutrients to produce useful energy stores C. the use of chemical energy to transport organelles through the cytosol D. the use of heat to burn foodstuffs and transport glucose

D. the use of heat to burn foodstuffs and transport glucose **Cells do not use heat to burn foodstuffs; they use a series of catabolic reactions that allow them to break down foods and capture some of this chemical energy to power other activities in the cell. Some of this chemical energy is lost as heat. Normal cellular activities include the use of chemical energy to transport organelles through the cytosol, the conversion of sunlight into energy stored in chemical bonds during photosynthesis, and the metabolism of nutrients to produce useful energy stores.

In this simplified diagram of the reactions of the carbon-fixation cycle, which step is catalyzed by the enzyme Rubisco?

E *Rubisco catalyzes the addition of CO2 to a five-carbon molecule of ribulose 1,5-bisphosphate to produce two three-carbon molecules.

Which of the following represents energy in its most disordered form? A. potential energy B. chemical bond energy C. kinetic energy of a moving object D. electromagnetic (light) energy E. heat energy

E. heat energy

(Q002) Why do cells use enzymes to harvest energy from food molecules rather than by direct oxidation? Enzymes transfer energy from food to carrier molecules in small steps. Enzymes release all the energy from food molecules in a single efficient step. Direct oxidation cannot release all the energy from food molecules. Direct oxidation is energetically unfavorable.

Enzymes transfer energy from food to carrier molecules in small steps. *if it was one step too much energy would be released as heat

Which activated carriers are produced by the citric acid cycle? CO2 GTP NADPH FADH2 ATP NADH

GTP FADH2 NADH

In the electron transport chain, the oxygen atoms in O2 become part of which of the following molecules? glucose (C6H12O6) ATP H2O NADH CO2

H2O

When an electron is removed from the reaction center of photosystem II, the missing electron is replaced by an electron from which of the following? manganese H+ sunlight photosystem I H2O

H2O

During electron transport, which serves as a ready source for protons that can be pumped across the membrane? ATP NADH O2 H2O glucose

H2O *NADH produces H- ion

When the difference in redox potential between two molecules is highly positive, what is true of the transfer of electrons between them? It is highly unfavorable. It requires an input of energy. It is accompanied by a rise in ΔG. It produces ATP. It is highly favorable.

It is highly favorable.

What happens to the energy captured during glycolysis and the citric acid cycle by the activated carriers NADH and FADH2. It is used to drive biosynthetic reactions. It is passed to an electron transport chain that uses it to generate a proton gradient across the inner mitochondrial membrane. It is passed to an electron transport chain that uses it to produce oxygen. It is passed to ADP to form ATP. It is passed to an electron transport chain that uses it to oxidize food molecules.

It is passed to an electron transport chain that uses it to generate a proton gradient across the inner mitochondrial membrane.

What is true of stage 2 of photosynthesis? It produces glyceraldehyde 3-phosphate in the stroma. It produces all of the O2 we breathe. It generates a proton gradient across the thylakoid membrane. It begins with the production of ATP and NADPH and ends with their consumption. It takes place in the chloroplast grana.

It produces glyceraldehyde 3-phosphate in the stroma. *In stage 2 of photosynthesis, which begins in the stroma, the ATP and the NADPH produced in stage 1 are used to drive the manufacture of glyceraldehyde 3-phosphate from CO2.

(Q019) Which of the following has a higher concentration in the cell to allow it to be available to accept electrons from oxidation of food molecules? NAD+ NADH NADPH NADP+

NAD+

Although the citric acid cycle itself does not use O2, it requires a functioning electron transport chain (which uses O2) in order to regenerate which molecule for further use in the citric acid cycle? NAD+ ATP FADH2 NADH ADP

NAD+

(Q006) The citric acid cycle produces which activated carriers that transfer high-energy electrons to the electron-transport chain? NADPH and NADH NAD+ and FAD NADP and FAD NADH and FADH2

NADH and FADH2

(Q008) If cells were undergoing glycolysis but could not carry out fermentation, what products would build up in the cytosol? NADH and pyruvate ADP and CO2 H2O and citric acid NAD+ and ATP

NADH and pyruvate *end products are NADH and pyruvate, no fermentation means no reproduction of NAD+

(Q009) Which of the following has the lowest electron affinity? NADH dehydrogenase complex cytochrome c reductase complex cytochrome c oxidase complex oxygen

NADH dehydrogenase complex

Most of the energy for the synthesis of ATP comes from which molecule? NADH produced by the citric acid cycle GTP produced by the citric acid cycle FADH2 produced by the citric acid cycle NADH produced by the conversion of pyruvate to acetyl CoA NADH produced by glycolysis

NADH produced by the citric acid cycle

During Earth's history, with the rise of cyanobacteria, what molecule began accumulating in the atmosphere for the first time? CO2 O2 N2 H2O

O2

CO2 is released in which steps of the citric acid cycle, as shown below? Steps 2 and 4 Steps 2, 3, and 4 Steps 1 and 5 Steps 1 and 8 Steps 3 and 4

Steps 3 and 4

(Q017) Cytochrome c oxidase catalyzes the reaction that reduces molecular oxygen (two oxygen atoms) to two water molecules. The electrons are added sequentially, and during the process cytochrome c oxidase must bind the oxygen tightly in the active site. Why? If the oxygen escapes, it will bubble out as a gas and escape quickly. Superoxide radicals are formed as an intermediate, and are dangerous to the cell. Oxygen will bind to the electron-transport chain and reverse the pumping of protons. The escaped oxygen will form carbon monoxide and kill the cell.

Superoxide radicals are formed as an intermediate, and are dangerous to the cell.

(Q012) For a reaction Y à X with a very high equilibrium constant, K, which of the following is true? The amount of product will be higher than the amount of substrate at equilibrium. The forward reaction rate greatly exceeds the reverse reaction rate at equilibrium. The standard free-energy change is large and positive. The amount of product and substrate are equal at equilibrium.

The amount of product will be higher than the amount of substrate at equilibrium.

What is one reason that plants do not generally produce sugars after dark? CO2 is unavailable after dark. The enzymes involved in stage 1 of photosynthesis are inactivated in the dark. O2 is unavailable after dark. The enzymes involved in stage 2 of photosynthesis are inactivated in the light. The enzymes involved in stage 2 of photosynthesis are inactivated in the dark.

The enzymes involved in stage 2 of photosynthesis are inactivated in the dark. *In addition to requiring the ATP and NADPH produced by the light-dependent reactions in stage 1 of photosynthesis, several of the enzymes required for carbon fixation are inactivated in the dark and reactivated by light-stimulated electron transport.

(Q004) In a sperm cell, where are the mitochondria located? The mitochondria form elongated tubes that wrap around the flagellar core. They are located in a tubular network that are just inside the plasma membrane. Mitochondria are randomly scattered around in the cytoplasm of the cell. The mitochondria surround the nucleus of the cell.

The mitochondria form elongated tubes that wrap around the flagellar core.

(Q018) Why is the oxidation of NADPH energetically favorable? The oxidized form of NADPH is more stable than the reduced form. NADPH is the form of the molecule that can gain two high-energy electrons. The biosynthetic reactions that are coupled to NADPH oxidation are energetically favorable. Oxidation of NADPH breaks a high-energy phosphoanhydride bond.

The oxidized form of NADPH is more stable than the reduced form. *NADP+ (oxidized) is more stable!! chose c but it was wrong

(Q018) Shown below (second figure) is the mechanism believed to be used for pumping protons by cytochrome c oxidase across the inner mitochondrial membrane. One of the steps shown is unidirectional because it is driven by the energy of electron transport. Why must this step be performed only in one direction? The protons could be also captured from the intermembrane space and released back into the matrix. The complex would stay stuck in the closed (center conformation). The inner membrane would become porous to all molecules. The H+ affinity in the two conformations would reverse.

The protons could be also captured from the intermembrane space and released back into the matrix.

(Q015) Which of the following is a reason why ATP hydrolysis has a negative ΔG0? ATP has a high concentration in cells. The removal of the phosphate is energetically favorable. The reverse reaction is extremely fast. The products have more free energy than the reactants.

The removal of the phosphate is energetically favorable.

For the simple reaction Y → X, the equilibrium constant K is equal to which of the following equations? [X] × [Y] [Y] × [X] [Y] / [X] [X] / [Y]

[X] / [Y]

(Q020) In oxidative phosphorylation in mitochondria, high-energy electrons are transferred to the electron-transport chain from activated carriers like NADH. Stage 1 of photosynthesis also uses an electron-transport chain to pump protons and make ATP. In this case, where do the high-energy electrons come from? NADPH chlorophyll ADP FADH2

chlorophyll

How do enzymes maximize the energy harvested from the oxidation of food molecules? They allow the stepwise oxidation of food molecules, which releases energy in small amounts. They allow a larger amount of energy to be released from food molecules such as glucose. They guarantee that each reaction involved in the oxidation of food molecules proceeds in just one direction. They allow what would otherwise be an energetically unfavorable oxidation reaction to occur. They allow oxidation reactions to take place without an input of activation energy.

They allow the stepwise oxidation of food molecules, which releases energy in small amounts. *Enzymes allow cells to carry out the oxidation of sugars in a tightly controlled stepwise series of reactions. These reactions pay out energy in small packets to activated carriers, which allows cells to capture much of the energy released by the oxidative breakdown of glucose in the high-energy bonds of ATP and other activated carriers.

What is true of the evolution of electron transport systems? A. The earliest ones involved using H2O as an electron donor. B. They are a relatively recent evolutionary innovation. C. Their requirement for oxygen as an electron acceptor means they evolved first in photosynthetic prokaryotes. D. They are evolutionarily ancient and likely provided energy for the earliest cells on Earth. E. In ancient prokaryotes, they did not require the use of a membrane.

They are evolutionarily ancient and likely provided energy for the earliest cells on Earth.

(Q007) How do the high-energy electrons of activated carriers contribute to forming the high-energy phosphate bonds of ATP? They are transferred directly to ADP to form ATP. They are passed to ATP synthase to power ATP synthesis. They are used by the electron-transport chain to make a proton gradient. They are pumped across the membrane to form an electron gradient.

They are used by the electron-transport chain to make a proton gradient.

(Q014) What is the role of activated carriers in cells? They are enzymes that catalyze biosynthetic reactions and make them feasible at the temperature of a cell. They capture energy from energy releasing reactions and transfer it to other reactions. They are enzymes that catalyze the reactions that break down foodstuffs for energy generation in the cell. They carry energy from anabolic reactions for use in catabolic reactions.

They capture energy from energy releasing reactions and transfer it to other reactions.

What is true of the organelles that produce ATP in eukaryotic animal cells? They harbor eukaryotic-like biosynthetic machinery for making RNA and protein. They evolved from bacteria engulfed by ancestral cells billions of years ago. They contain the same genes as the chloroplasts of plant cells. They reproduce sexually. They have a separate set of DNA that contains many of the same genes found in the nucleus.

They evolved from bacteria engulfed by ancestral cells billions of years ago.

Which two-carbon molecule enters the citric acid cycle? pyruvate acetyl CoA oxaloacetate carbon dioxide citrate

acetyl CoA

(Q011) Fatty acids can be used to produce energy by conversion to ___________ in the ___________ of the cell. acetyl CoA; mitochondria pyruvate; endoplasmic reticulum lipids; plasma membrane NADH; cytosol

acetyl CoA; mitochondria *Fatty acid --> acetyl CoA

For a biochemical reaction, _______ energy is the term for the extra energy boost required to initiate an energetically favorable reaction within the cell.

activation

Reactions that use energy to drive the synthesis of molecules inside the cell are most specifically considered _________

anabolic

(Q001) Reactions that build larger molecules in the cell are called ___________; reactions that break down molecules into smaller ones are called ___________. anabolic; catabolic catabolic; anabolic anabolic; metabolic metabolic; anabolic

anabolic; catabolic

(Q003) Why is sunlight the ultimate source of energy for nearly all living things on Earth? a. because the Earth makes a full rotation on it's axis, which provides light once a day b. because photosynthetic organisms produce food molecules using light energy c. because animals obtain heat energy from the sun, which keeps them alive d. because all animals must consume plants for obtaining energy

b. because photosynthetic organisms produce food molecules using light energy *

(Q006) Why is CO2 an end product of cellular respiration? because it is the most stable form of carbon in our atmosphere because it can accept electrons and produce a reduced form of carbon because it captures light energy for photosynthesis because plants can use it for respiration

because it is the most stable form of carbon in our atmosphere

(Q012) Why is the presence of oxygen required for the citric acid cycle to operate? because oxygen combines with carbon from acetyl CoA to form the citric acid product CO2 because the NADH passes its electrons to oxygen in the electron transport chain to renew NAD+ because oxygen oxidizes several enzymes in the citric acid cycle because oxygen forms the water that is used in hydrolysis reactions in the citric acid cycle

because the NADH passes its electrons to oxygen in the electron transport chain to renew NAD+

(Q004) Cellular respiration ___________ and produces ___________, whereas photosynthesis ___________ and produces ___________. a. requires energy input; oxygen + sugars; releases energy; water + carbon dioxide b. releases energy; oxygen + sugars; requires energy input; water + carbon dioxide c. requires energy input; water + carbon dioxide; releases energy; oxygen + sugars d. releases energy; water + carbon dioxide; requires energy input; oxygen + sugars

d. releases energy; water + carbon dioxide; requires energy input; oxygen + sugars #*cellular respiration breaks down releasing energy making water and co2; photosynthesis uses energy to make oxygen and sugars

(Q017) What purpose does NADPH serve in biosynthetic reactions like the one pictured below? accepting electrons from an oxidation reaction donating electrons for a reduction reaction storing energy in high-energy phosphate groups releasing energy from high-energy phosphate groups

donating electrons for a reduction reaction

(Q014) What is the role of oxygen in the electron transport chain? electron acceptor coenzyme reducing agent transporter

electron acceptor

Which of the following processes generates the largest number of ATP molecules? fermentation citric acid cycle gluconeogenesis glycolysis electron transport chain

electron transport chain *glycolysis only forms gtp

You are packing for a hiking trip during which you'll be burning a lot of calories with physical activity. You want to pack as efficiently as possible since you need to carry a tent and all your food. You can get the most calories out of 5kg of food if it is in the form of ______

fat

(Q023) The first living things on Earth probably generated ATP by what mechanism? fermentation oxidative phosphorylation photosynthesis carbon fixation

fermentation

Under anaerobic conditions, which metabolic pathway regenerates the supply of NAD+ needed for glycolysis? formation of acetyl CoA citric acid cycle fermentation breakdown of fats breakdown of amino acids

fermentation *Fermentation reactions convert the pyruvate produced during glycolysis into lactate or ethanol. In the process, NADH gives up its electrons, thereby producing NAD+.

The NADH generated during glycolysis and the citric acid cycle feeds its high-energy electrons to which of the following? FAD the electron transport chain ADP the citric acid cycle H2O

the electron transport chain

(Q017) What is gluconeogenesis? the synthesis of glucose from pyruvate the mobilization of glucose from glycogen stores the production of glucose from starch the blockage of glycolysis at the first step

the synthesis of glucose from pyruvate

What does the term "gluconeogenesis" refer to? the synthesis of glucose from small organic molecules such as pyruvate the transport of glucose across a cell membrane the breakdown of glucose during fermentation the release of glucose from molecules such as glycogen the breakdown of glucose during glycolysis

the synthesis of glucose from small organic molecules such as pyruvate

(Q019) Shown is a chloroplast with labeled structures. The photosynthetic machinery is found in which of the compartments shown? stroma thylakoid membrane inner membrane outer membrane

thylakoid membrane

(Q005) What is the function of a kinase? to oxidize a molecule to add a phosphate group to a molecule to rearrange the bonds into an isomeric form to shift a chemical group from one position to another in a molecule

to add a phosphate group to a molecule

In what form do plant and animal cells store fat? triacylglycerol glycogen nitroglycerin phospholipids starch

triacylglycerol *Correct. The triacylglycerol in plants and animals differs only in the types of fatty acids that predominate: plant oils contain unsaturated fatty acids (with one or more double bonds) and animal fats are saturated.

(Q004) During glycolysis, the number of ATP consumed (per glucose molecule) is ___________, while the number produced is ___________. one; two two; four six; thirty-six four; two

two; four

(Q015) Glycolysis produces ___________ ATP molecules, whereas the complete oxidation of glucose to water and carbon dioxide produces ___________ ATP molecules. two; ten four; thirty-four two; thirty four; twenty

two; thirty *glycolysis produces NET of 2 ATP

(Q008) Which of the following is a mobile electron carrier in the electron-transport chain? NADH dehydrogenase complex cytochrome c reductase complex cytochrome c oxidase complex ubiquinone

ubiquinone

(Q020) Condensation reactions are energetically ___________ and hydrolysis reactions are energetically ___________. unfavorable; unfavorable favorable; favorable favorable; unfavorable unfavorable; favorable

unfavorable; favorable

(Q011) What is the relationship between ΔG and ΔG0? ΔG0 is the free-energy change at standard temperature. ΔG0 is the free-energy change at standard pressure. ΔG0 is the free-energy change at standard concentrations. ΔG0 is the free-energy change at standard temperature and concentrations.

ΔG0 is the free-energy change at standard temperature and concentrations.