Bio Test 2 Practice, Exam 2

How many oxygen molecules are required each time a molecule of glucose is completely oxidized to carbon dioxide and water vie aerobic respiration

6

A mutation in yeast makes it unable to convert pyruvate to ethanol. How will this mutation affect these yeast cells? A. The mutant yeast will be unable to grow anaerobically. B. The mutant yeast will be unable to metabolize glucose. C. The mutant yeast will metabolize only fatty acids. D. The mutant yeast will die because they cannot regenerate NAD+ from NAD. E. The mutant yeast will grow anaerobically only when given glucose.

A

Brown fat cells produce a protein called thermogenin in their mitochondrial inner membrane. Thermogenin is a channel for facilitated transport of protons across the membrane. What will occur in the brown fat cells when they produce thermogenin? A. ATP synthesis will decrease, and heat generation will increase. B. ATP synthesis and heat generation will both increase. C. ATP synthesis and heat generation will both decrease. D. ATP synthesis will increase, and heat generation will decrease. E. ATP synthesis and heat generation will stay the same.

A

During intense exercise, as skeletal muscle cells switch to fermentation, the human body will increase its catabolism of A. carbohydrates only. B. proteins only. C. fats, carbohydrates, and proteins. D. fats and proteins only. E. fats only.

A

Even though plants carry on photosynthesis, plant cells still use their mitochondria for oxidation of pyruvate. When and where will this occur? A. in all cells all the time B. in photosynthesizing cells in the light and in other tissues in the dark C. in cells that are storing glucose only D. in photosynthetic cells in the light, while photosynthesis occurs concurrently E. in nonphotosynthesizing cells only

A

In a mitochondrion, if the matrix ATP concentration is high, and the intermembrane space proton concentration is too low to generate sufficient proton-motive force, then A. ATP synthase will hydrolyze ATP and pump protons into the intermembrane space. B. ATP synthase will stop working. C. ATP synthase will hydrolyze ATP and pump protons into the matrix. D. ATP synthase will increase the rate of ATP synthesis.

A

During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level? A. NAD+ B. ADP +P i C. FADH2 D. ATP E. NADH

C

During glycolysis, when each molecule of glucose is catabolized to two molecules of pyruvate, most of the potential energy contained in glucose is A. stored in the NADH produced. B. transferred to ADP, forming ATP. C. retained in the two pyruvates. D. used to phosphorylate fructose to form fructose 6-phosphate. E. transferred directly to ATP.

C

If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized to carbon dioxide and water, approximately how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water? A. 26 B. 12 C. 14 D. 0 E. 1

C

In addition to ATP, what are the end products of glycolysis? A. CO2and NADH B. CO2 and pyruvate C. NADH and pyruvate D. CO2 and H2O E. H2O , FADH2, and citrate

C

Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C6H12O6) in aerobic cellular respiration? A. 30-32 B. 4 C. 15 D. 2 E. 60-64

E

During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from? A. glucose B. carbon dioxide C. pyruvate D. lactate E. molecular oxygen

E

During aerobic respiration, electrons travel downhill in which sequence? A. food → glycolysis → citric acid cycle → NADH → ATP B. glucose → ATP → electron transport chain → NADH C. glucose → pyruvate → ATP → oxygen D. food → citric acid cycle → ATP → NAD+ E. food → NADH → electron transport chain → oxygen

E

During cellular respiration, acetyl CoA accumulates in which location? A. cytosol B. mitochondrial inner membrane C. mitochondrial outer membrane D. mitochondrial intermembrane space E. mitochondrial matrix

E

What is the function of extracellular matrix (ECM)?

For cells ECM provides: mechanical support a biochemical barrier a medium for: extracellular communication that is assisted by CAMs (cell adhesion molecules) the stable positioning of cells in tissues through cell matrix adhesion the repositioning of cells by cell migration during cell development and wound repair

vacuole

Found in Plant cells. Stores water and other substances

nucleolus

Found inside the nucleus and produces ribosomes

gap junction

Junction between cells formed by the joining of two adjacent plasma membranes.

What is the function of keratin?

Keratin is an important protein in the epidermis. Keratin has two main functions; to adhere cells to each other, and to form a protective layer on the outside of the skin. In epithelial cells, keratin proteins inside the cell attach to proteins called desmosomes on the surface. (desmosome = a structure by which two adjacent cells are attached, formed from protein plaques in the cell membranes linked by filaments.)

What is the function of kinesin? How does its structure relate to its function?

Kinesin converts the chemical energy in ATP into mechanical energy in the form of movement. More specifically, when ATP is hydrolyzed by kinesin, the protein moves along microtubules in a directional manner: toward the plus end The current model depicting how kinesin "walks" along a microtubule track to transport vesicles. The two head segments act like feet that alternately attach, pivot, and release in response to the gain or loss of a phosphate group from ATP.

ribosomes

Makes proteins

In the Calvin cycle, why are fewer than six RuBP molecules required to fix six molecules of CO2?

RuBP is regenerated in the Calvin cycle. In the regeneration phase of the Calvin cycle, the carbon skeletons of five G3P molecules are rearranged into three RuBP molecules, so fewer than six RuBP molecules are required to fix six CO2.

Carbon fixation involves the addition of carbon dioxide to ___

RuBP

Why are receptors for steroid hormones located inside the cell rather than on the membrane surface?

Since steroids are lipids, they can pass the lipid membrane and therefore their receptors are located inside of the cell

How many carbon dioxide molecules must be added to RuBP to make a single molecule of glucose?

Six carbon dioxide molecules are required to produce two G3P molecules, which can be combined to make one glucose molecule.

what enters the citric acid cycle

acetyl CoA

following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the original glucose molecule at that point in the process, however, is in the form of

acetyl-CoA

what three things make up the cytoskeleton of cells

actin filaments (microfilaments), intermediate filaments, and microtubules

what event accompanies energy absorption by chlorophyll (or other pigmnt molecules of the antenna complex)?

an electron is excited

electrons have more potential energy when they are in electron shells

away from the nucleus. In this position they are farther from the positively charged protons and are hence less stable, with more potential energy.

what has an identical structure to centrioles

basal bodies

mitochondrion

bean-shaped organelle that supplies energy to the cell and has its own ribosomes and DNA.

Why oils are liquid at room temperature?

because they have unsaturated bonds that do stack well, they are not solid.

Chlorophylls adsorb light in which colors of the visible range

blue and red

What are the second messenger molecules?

cAMP, DAG, IP3, cGMP, Ca2+

What molecule is produced in the citric acid cycle as a by-product of glucose oxidation and is considered a waste product?

carbon dioxide. Carbon dioxide is not processed further and is removed from the organism.

what is a difference between chlorophyll a and chlorophyll b

chlorophyll a and b absorb light energy at slightly different wavelengths

only plant cells have:

chloroplasts and vacuoles

which of the following statements about cellular metabolism is false

citric acid cycle activity is dependent solely on availability of substrate, otherwise it is unregulated

During pyruvate processing, two carbons from pyruvate combine with ____

coenzyme A. One carbon of the three-carbon pyruvate becomes oxidized to CO2 and the remaining two carbons (acetate) combine with coenzyme A to form acetyl coenzyme A

smooth endoplasmic reticulum

creates lipids or fat

all cells have:

cytoplasm, ribosomes, genetic information, cytoskeleton, and plasma membrane

What is diffusion in terms of thermodynamics? Why diffusion occurs spontaneously?

diffusion is a spontaneous process that contributes to the overall entropy of a molecule

peroxisome

enzyme-filled vesicle that breaks down amino acids, fatty acids, and toxic substances.

which process in eukaryotic cells will proceed normally whether oxygen is present or absent

glycolysis

what are the by-products of cellular respiration?

heat, water, and carbon dioxide

what is the by-product formed by peroxisomes

hydrogen peroxide

chlorophyll molecules donate electrons to an electron acceptor ____

in the reaction center. Reaction center chlorophylls are the only chlorophylls that donate electrons to an electron acceptor.

In eukaryotes, the components of the electron transport chain are located in the ____

inner mitochondrial membrane. Proteins in the mitochondrial inner membrane pump protons into the intermembrane space, creating a proton motive force.

Describe the function of integrins.

integrins connect the extracellular matrix to the cytoskeleton

nuclear envelope

the double membrane that surrounds the nucleus

what modifies, stores, and packages products of the ER

the golgi apparatus

How do the length and saturation of fatty acids in the membrane phospholipids effect the structure and function of membrane?

the longer and more saturated a fatty acid is, the more rigid and solid the membrane is

How do proteins find their way into the organelles?

1. proteins made by ribosomes enter the ER 2. molecules synthesized in the ER are transported to the golgi apparatus 3. the golgi sorts them by "zip code" in specific vesicles 4. the vesicles interact with receptor proteins at the target location so that the contentsa re delivered correctly

What is the function of signal sequence on polypeptides synthesized by ribosomes that are not attached to the endoplasmic reticulum?

1. signal sequence is synthesized by ribosome 2. signal sequence binds to signal recognition particle (SRP) and halts synthesis. 3. SRP binds to receoptor in ER membrane 4. SRP is released. protein synthesis continues. protein enters the ER. 5. signal sequence is removed. protein synthesis then proceeds to completion. It allows the protein destined for secretion being made by the ribosome to enter the endomembrane system.

Photosystem II splits water into

1/2 O2, H+, and e- .

How many NADH are produced by glycolysis?

2

In glycolysis there is a net gain of _____ ATP.

2

in the carbon fixation step of the calvin cycle, ribulose-1,5-biphosphate is carboxylated to produce

2 three-carbon compounds

In the Calvin cycle, how many ATP molecules are required to regenerate RuBP from five G3P molecules?

3

Inside an active mitochondrion, most electrons follow which pathway? A. citric acid cycle → NADH → electron transport chain → oxygen B. glycolysis → NADH → oxidative phosphorylation → ATP → oxygen C. citric acid cycle → FADH2 → electron transport chain → ATP D. pyruvate → citric acid cycle → ATP → NADH → oxygen E. electron transport chain → citric acid cycle → ATP → oxygen

A

Select all that apply. A. The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis. B. The basic function of fermentation is the production of ethyl alcohol or lactic acid. C. The basic function of fermentation is the production of additional ATP by further oxidation of the products of glycolysis.

A

Select the correct statement about cellular respiration. A. Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level. B. Animals carry out cellular respiration whereas plants carry out photosynthesis. C. Plants carry out cellular respiration only in organs such as roots that cannot carry out photosynthesis.

A

The citric acid cycle. For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of are released in the citric acid cycle (see the figure)? A. 4 B. 3 C. 2 D. 12 E. 6

A

When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes A. reduced. B. oxidized. C. redoxed. D. dehydrogenated. E. hydrolyzed.

A

When an individual is exercising heavily and when the muscle becomes oxygen-deprived, muscle cells convert pyruvate to lactate. What happens to the lactate in skeletal muscle cells? A. It is taken to the liver and converted back to pyruvate. B. It produces and water. C. It is converted to NAD+. D. It is converted to alcohol. E. It reduces FADH2 to FAD+.

A

Which kind of metabolic poison would most directly interfere with glycolysis? A. an agent that closely mimics the structure of glucose but is not metabolized B. an agent that reacts with NADH and oxidizes it to NAD+ C. an agent that reacts with oxygen and depletes its concentration in the cell D. an agent that binds to pyruvate and inactivates it E. an agent that blocks the passage of electrons along the electron transport chain

A

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule? A. glycolysis B. the citric acid cycle C. the electron transport chain D. synthesis of acetyl CoA from pyruvate E. reduction of pyruvate to lactate

A

Which of the following normally occurs regardless of whether or not oxygen is present? A. glycolysis B. oxidative phosphorylation (chemiosmosis) C. oxidation of pyruvate to acetyl CoA D. fermentation E. citric acid cycle

A

Which of the following occurs in the cytosol of a eukaryotic cell? A. glycolysis and fermentation B. citric acid cycle C. fermentation and chemiosmosis D. oxidative phosphorylation E. oxidation of pyruvate to acetyl CoA

A

Which of the following statements accurately describes the function of a metabolic pathway involved in cellular respiration? A. The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP. B. 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. C. The function of the citric acid cycle is the transfer of electrons from pyruvate to NADH to O2.

A

You have a friend who lost 7 kg (about 15 pounds) of fat on a regimen of strict diet and exercise. How did the fat leave her body? A. It was released CO2 as and H20 . B. It was converted to heat and then released. C. It was broken down to amino acids and eliminated from the body. D. It was converted to ATP, which weighs much less than fat. E. It was converted to urine and eliminated from the body.

A

which of the following statements concerning chloroplasts is false A. they are unrelated to plants B. they have outer and inner membranes C. they have their own DNA D. They have an internal membrane system known as the thylakoids

A

plasma membrane

A selectively-permeable phospholipid bilayer forming the boundary of the cells

golgi apparatus

A system of membranes that modifies and packages proteins for export by the cell

In glycolysis, what starts the process of glucose oxidation?

ATP

What is the chemiosmotic hypothesis?

ATP is generated using a proton-motive force that is produced by the electron transport chain.

Why is ATP production during cellular respiration characterized as indirect

ATP is not produced directly by the ETC but instead via the proton gradient generated during electron transport through the ETC. Biologists characterize ATP production as indirect because ATP is not synthesized by the ETC (or associated enzymes) via substrate-level phosphorylation.

What is the form of energy extracted from glucose in the energy‐yielding phase of glycolysis?

ATP.

What form of ATP has the highest energy

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.

Where are the proteins of the electron transport chain located? A. mitochondrial outer membrane B. mitochondrial inner membrane C. mitochondrial matrix D. cytosol E. mitochondrial intermembrane space

B

what is kinase?

An enzyme that transfers phosphate ions from one molecule to another

lysosome

An organelle containing digestive enzymes

chloroplast

An organelle found in plant and algae cells where photosynthesis occurs

An electron loses potential energy when it A. shifts to a less electronegative atom. B. shifts to a more electronegative atom. C. increases its activity as an oxidizing agent. D. moves further away from the nucleus of the atom. E. increases its kinetic energy.

B

Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells? A. mitochondrial matrix B. mitochondrial intermembrane space C. mitochondrial outer membrane D. mitochondrial inner membrane E. cytosol

B

How will a healthy individual's ATP production change during an eight-hour fast? A. The individual's ATP production will increase significantly. B. The individual's ATP production will not change significantly. C. The individual's ATP production will decrease significantly.

B

In alcohol fermentation, NAD+ is regenerated from NADH by A. reduction of pyruvate to form lactate. B. reduction of acetaldehyde to ethanol (ethyl alcohol). C. oxidation of pyruvate to acetyl CoA. D. oxidation of ethanol to acetyl CoA. E. reduction of ethanol to pyruvate.

B

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? A. The advantage of an electron transport chain is the production of a large number of reduced, high-energy intermediates. B. 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. C. The advantage of the respiratory electron transport chain is that oxygen is the final electron acceptor.

B

In chemiosmosis, what is the most direct source of energy that is used to convert ADP + ADP +Pi to ATP? A. energy released from dehydration synthesis reactions B. energy released from movement of protons through ATP synthase, down their electrochemical gradient C. energy released as electrons flow through the electron transport system D. No external source of energy is required because the reaction is exergonic. E. energy released from substrate-level phosphorylation

B

In prokaryotes, the respiratory electron transport chain is located A. in the mitochondrial outer membrane. B. in the plasma membrane. C. in the mitochondrial inner membrane. D. in the bacterial outer membrane. E. in the cytoplasm.

B

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 A. inhibit the enzyme and thus increase the rates of glycolysis and the citric acid cycle. B. inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle. C. activate the enzyme and thus slow the rates of glycolysis and the citric acid cycle. D. activate the enzyme and increase the rates of glycolysis and the citric acid cycle. E. inhibit the enzyme and thus increase the rate of glycolysis and the concentration of citrate.

B

The ATP made during fermentation is generated by which of the following? A. chemiosmosis B. substrate-level phosphorylation C. aerobic respiration D. oxidative phosphorylation E. the electron transport chain

B

The citric acid cycle. For each molecule of glucose that is metabolized by glycolysis and the citric acid cycle (see the figure), what is the total number of NADH + FADH2 molecules produced? A. 5 B. 12 C. 10 D. 4 E. 6

B

The citric acid cycle. If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the figure? A. Oxaloacetate will decrease and citric acid will accumulate. B. Both oxaloacetate and citric acid will decrease. C. Both oxaloacetate and citric acid will accumulate. D. There will be no change in the levels of oxaloacetate and citric acid. E. Oxaloacetate will accumulate and citric acid will decrease.

B

The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction A. loses electrons and gains potential energy. B. loses electrons and loses potential energy. C. gains electrons and loses potential energy. D. gains electrons and gains potential energy. E. neither gains nor loses electrons, but gains or loses potential energy.

B

What is proton-motive force? A. the force that moves hydrogen to NAD+ B. the force provided by a transmembrane hydrogen ion gradient C. the force that moves hydrogen into the intermembrane space D. the force that moves hydrogen into the mitochondrion E. the force required to remove an electron from hydrogen

B

What is the term for metabolic pathways that release stored energy by breaking down complex molecules? A. bioenergetic pathways B. catabolic pathways C. fermentation pathways D. anabolic pathways E. thermodynamic pathways

B

When electrons move closer to a more electronegative atom, what happens? A. The more electronegative atom is oxidized, and energy is released. B. The more electronegative atom is reduced, and energy is released. C. The more electronegative atom is reduced, and entropy decreases. D. The more electronegative atom is oxidized, and energy is consumed. E. The more electronegative atom is reduced, and energy is consumed.

B

Which of the following statements describes the results of this reaction? C6H12O6+ 602--> 6CO2 + 6H20 + Energy A. CO2 is reduced and is O2 oxidized. B. C6H12O6 is oxidized and 02 is reduced. C. C6H12O6 is reduced and CO2 is oxidized. D. O2 is reduced and CO2 is oxidized. E. O2 is oxidized and H20 is reduced.

B

Why are carbohydrates and fats considered high energy foods? A. They can have very long carbon skeletons. B. They have a lot of electrons associated with hydrogen. C. They have no nitrogen in their makeup. D. They have a lot of oxygen atoms. E. They are easily reduced.

B

if you introduce rediolabeled carbon dioxide into plants, which of the following molecules should be expected to have radiolabel first

B-phosphoglycerate

A molecule that is phosphorylated A. has a decreased chemical reactivity; it is less likely to provide energy for cellular work. B. has less energy than before its phosphorylation and therefore less energy for cellular work. C. has an increased chemical potential energy; it is primed to do cellular work. D. has been reduced as a result of a redox reaction involving the loss of an inorganic phosphate. E. has been oxidized as a result of a redox reaction involving the gain of an inorganic phosphate.

C

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 , (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A. How does the addition of coenzyme A, a sulfur-containing molecule derived from a B vitamin, function in the subsequent reaction? A. It drives the reaction that regenerates NAD+. B. It utilizes this portion of a B vitamin, which would otherwise be a waste product from another pathway. C. It provides a relatively unstable molecule whose acetyl portion can be readily transferred to a compound in the citric acid cycle. D. It removes one molecule of CO2. E. It provides the sulfur needed for the molecule to enter the mitochondrion.

C

Most CO2 from catabolism is released during A electron transport. B. lactate fermentation. C. the citric acid cycle. D. oxidative phosphorylation. E. glycolysis.

C

One function of both alcohol fermentation and lactic acid fermentation is to A. reduce NAD+ to NADH. B. reduce FAD+ to FADH2. C. oxidize NADH to NAD+. D. reduce FADH2 to FAD+. E. do none of the above.

C

Starting with one molecule of glucose, the energy-containing products of glycolysis are A. 6 CO2, 2 pyruvate, and 30 ATP. B. 6 CO2, 2 pyruvate, and 2 ATP. C. 2 NADH, 2 pyruvate, and 2 ATP. D. 2 FADH2, 2 pyruvate, and 4 ATP. E. 2 NAD+, 2 pyruvate, and 2 ATP.

C

Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis? A. 2% B. 0% C. 100% D. 10% E. 38%

C

The ATP made during glycolysis is generated by A. photophosphorylation. B. oxidation of NADH to NAD+. C. substrate-level phosphorylation. D. electron transport. E. chemiosmosis.

C

The citric acid cycle Starting with one molecule of isocitrate and ending with fumarate, how many ATP molecules can be made through substrate-level phosphorylation (see the figure)? A. 12 B. 11 C. 1 D. 2 E. 24

C

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is A. pyruvate. B. ADP. C. oxygen. D. NAD+. E. water.

C

The oxygen consumed during cellular respiration is involved directly in which process or event? A. glycolysis B. the citric acid cycle C. accepting electrons at the end of the electron transport chain D. the phosphorylation of ADP to form ATP E. the oxidation of pyruvate to acetyl CoA

C

What carbon sources can yeast cells metabolize to make ATP from ADP under anaerobic conditions? A. either ethanol or lactic acid B. ethanol C. glucose D. pyruvate E. lactic acid

C

What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ S Lactate + NAD+ A. NAD+ B. oxygen C. pyruvate D. NADH E. lactate

C

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes A. hydrolyzed. B. an oxidizing agent. C. oxidized. D. reduced. E. hydrogenated.

C

Where do the catabolic products of fatty acid breakdown enter into the citric acid cycle? A. malate or fumarate B. α-ketoglutarate C. acetyl CoA D. succinyl CoA E. pyruvate

C

Which of the following most accurately describes what is happening along the electron transport chain in the figure? A. Chemiosmosis is coupled with electron transfer. B. Energy of the electrons increases at each step. C. Molecules in the chain give up some of their potential energy. D. ATP is generated at each step. E. Each electron carrier alternates between being reduced and being oxidized.

C

Why is glycolysis described as having an investment phase and a payoff phase? A. It attaches and detaches phosphate groups. B. It both splits molecules and assembles molecules. C. It uses stored ATP and then forms a net increase in ATP. D. It uses glucose and generates pyruvate. E. It shifts molecules from cytosol to mitochondrion.

C

centrioles

Cell organelle that aids in cell division in animal cells only. cylinder-shaped organelles made of short microtubules arranged in a circle

What are the proteins found in the extracellular matrix of animal cells?

Collagen proteins are modified with carbohydrates, and once they're released from the cell, they assemble into long fibers called collagen fibrils Collagen plays a key role in giving tissues strength and structural integrity Additionally, proteins called integrins connect the extracellular matrix to the cytoskeleton

rough endoplasmic reticulum

Contains ribosomes; proteins are manufactured here.

A young animal has never had much energy. He is brought to a veterinarian for help and is sent to the animal hospital for some tests. There they discover his mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of his condition? A. His cells cannot move NADH from glycolysis into the mitochondria. B. His cells lack the enzyme in glycolysis that forms pyruvate. C. His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA. D. His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane. E. His cells contain something that inhibits oxygen use in his mitochondria.

D

An organism is discovered that thrives both in the presence and absence of oxygen in the air. Curiously, the consumption of sugar increases as oxygen is removed from the organism's environment, even though the organism does not gain much weight. This organism E. must use a molecule other than oxygen to accept electrons from the electron transport chain. A. is a normal eukaryotic organism. B. is photosynthetic. C. is an anaerobic organism. D. is a facultative anaerobe.

D

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration? A. glycolysis and the oxidation of pyruvate to acetyl CoA B. the citric acid cycle and oxidative phosphorylation C. fermentation and glycolysis D. oxidation of pyruvate to acetyl CoA and the citric acid cycle E. oxidative phosphorylation and fermentation

D

Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in A. only eukaryotic cells, in the presence of oxygen. B. all cells, in the absence of respiration. C. all cells, but only in the presence of oxygen. D. all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors. E. only in mitochondria, using either oxygen or other electron acceptors.

D

In cellular respiration, the energy for most ATP synthesis is supplied by A. converting oxygen to ATP. B. transferring electrons from organic mOlecules to pyruvate. C. generating carbon dioxide and oxygen in the electron transport chain. D. a proton gradient across a membrane. E. high energy phosphate bonds in organic molecules.

D

Phosphofructokinase is an important control enzyme in the regulation of cellular respiration. Which of the following statements correctly describes phosphofructokinase activity? A. It catalyzes the conversion of fructose 1,6-bisphosphate to fructose 6-phosphate, an early step of glycolysis. B. It is activated by ATP. C. It is activated by citrate, an intermediate of the citric acid cycle. D. It is an allosteric enzyme. E. It is inhibited by AMP.

D

The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation in eukaryotic cells is A. oxidation of glucose to and water. B. the thermodynamically favorable transfer of phosphate from glycolysis and the citric acid cycle intermediate molecules of ADP. C. the thermodynamically favorable flow of electrons from NADH to the mitochondrial electron transport carriers. D. the proton-motive force across the inner mitochondrial membrane. E. the final transfer of electrons to oxygen.

D

The free energy for the oxidation of glucose to CO2 and water is -686 kcal/mol and the free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed? A.Glycolysis is a very inefficient reaction, with much of the energy of glucose released as heat. B. Glycolysis consists of many enzymatic reactions, each of which extracts some energy from the glucose molecule. C. There is no CO2 or water produced as products of glycolysis. D. Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis. E. Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis.

D

The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the A. affinity of oxygen for electrons. B. transfer of phosphate to ADP. C. oxidation of glucose and other organic compounds. D. H+ concentration across the membrane holding ATP synthase. E. flow of electrons down the electron transport chain.

D

The primary role of oxygen in cellular respiration is to A. yield energy in the form of ATP as it is passed down the respiratory chain. B. catalyze the reactions of glycolysis. C. combine with lactate, forming pyruvate. D. act as an acceptor for electrons and hydrogen, forming water. E. combine with carbon, forming .

D

The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of A. a reaction with a positive ΔG . B. osmosis. C. allosteric regulation. D. an endergonic reaction coupled to an exergonic process. E. active transport.

D

Which catabolic processes may have been used by cells on ancient Earth before free oxygen became available? A. glycolysis, pyruvate oxidation, and the citric acid cycle B. glycolysis and the citric acid cycle only C. glycolysis and fermentation only D. glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation, using an electron acceptor other than oxygen E. oxidative phosphorylation only

D

Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide (CO2) and water? A. citric acid cycle B. glycolysis C. oxidation of pyruvate to acetyl CoA D. oxidative phosphorylation (chemiosmosis) E. fermentation

D

Which process in eukaryotic cells will proceed normally whether oxygen () is present or absent? A. oxidative phosphorylation B. electron transport C. the citric acid cycle D. glycolysis E. chemiosmosis

D

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? A. Glycolysis is found in all eukaryotic cells. B. Ancient prokaryotic cells, the most primitive of cells, made extensive use of glycolysis long before oxygen was present in Earth's atmosphere. C. Glycolysis neither uses nor needs . D. Glycolysis is widespread and is found in the domains Bacteria, Archaea, and Eukarya. E. The enzymes of glycolysis are found in the cytosol rather than in a membrane-enclosed organelle.

D

Why is glycolysis considered to be one of the first metabolic pathways to have evolved? A. It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells. B. It produces much less ATP than does oxidative phosphorylation. C. It is found in prokaryotic cells but not in eukaryotic cells. D. It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms. E. It relies on chemiosmosis, which is a metabolic mechanism present only in the first cells' prokaryotic cells.

D

Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy? A. glucose, proteins, and fatty acids B. fatty acids C. proteins D. glucose E. Such yeast cells will not be capable of catabolizing any food molecules, and will therefore die.

D

chromatin are composed of

DNA and protein

A young dog has never had much energy. He is brought to a veterinarian for help and she decides to conduct several diagnostic tests. She discovers that the dog's mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of the dog's condition? A. His cells contain something that inhibits oxygen use in his mitochondria. B. His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA. C. His cells lack the enzyme in glycolysis that forms pyruvate. D. His cells cannot move NADH from glycolysis into the mitochondria. E. His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.

E

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. After the disruption, when electron transfer and ATP synthesis still occur, what must be present? A. all of the electron transport system and the ability to add CoA to acetyl groups B. the ATP synthase system C. plasma membranes like those bacteria use for respiration D. the electron transport system E. all of the electron transport proteins as well as ATP synthase

E

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. These inside-out membrane vesicles A. will reverse electron flow to generate NADH from NAD+ in the absence of oxygen. B. will become alkaline inside the vesicles when NADH is added. C. will make ATP from ADP and i if transferred to a pH 4 buffered solution after incubation in a pH 7 buffered solution. D. will hydrolyze ATP to pump protons out of the interior of the vesicle to the exterior. E. will become acidic inside the vesicles when NADH is added.

E

How does the pyruvate produced by glycolysis enter the mitochondrion? A. facilitated diffusion B. through a channel C. through a pore D. diffusion E. active transport

E

How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate? A. four B. six C. ten D. eight E. two

E

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve? A. It increases the surface for substrate-level phosphorylation. B. It allows for an increased rate of glycolysis. C. It allows for an increased rate of the citric acid cycle. D. It allows the liver cell to have fewer mitochondria. E. It increases the surface for oxidative phosphorylation.

E

In mitochondria, exergonic redox reactions A. are the source of energy driving prokaryotic ATP synthesis. B. reduce carbon atoms to carbon dioxide. C. are directly coupled to substrate-level phosphorylation. D. are coupled via phosphorylated intermediates to ender-gonic processes. E. provide the energy that establishes the proton gradient.

E

In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of A. ATP, CO2, and lactate. B. ATP, pyruvate, and oxygen. C. ATP, pyruvate, and acetyl CoA. D. ATP, NADH, and pyruvate. E. ATP, CO2, and ethanol (ethyl alcohol)

E

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 , (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 A. acetyl CoA, FAD, , and . B. acetyl CoA, NAD+, ATP, and . C. acetyl CoA, FADH2, and . D. acetyl CoA, , and ATP. E. acetyl CoA, NADH, , and .

E

In vertebrate animals, brown fat tissue's color is due to abundant blood vessels and capillaries. White fat tissue, on the other hand, is specialized for fat storage and contains relatively few blood vessels or capillaries. Brown fat cells have a specialized protein that dissipates the proton-motive force across the mitochondrial membranes. Which of the following might be the function of the brown fat tissue? A. to increase the production of ATP B. to increase the rate of oxidative phosphorylation from its few mitochondria C. to allow the animals to regulate their metabolic rate when it is especially hot D. to allow other membranes of the cell to perform mitochondrial functions E. to regulate temperature by converting most of the energy from NADH oxidation to heat

E

It is possible to prepare vesicles from portions of the inner mitochondrial membrane. Which one of the following processes might still be carried on by this isolated inner membrane? A. the citric acid cycle B. both the citric acid cycle and oxidative phosphorylation C. reduction of NAD+ D. glycolysis and fermentation E. oxidative phosphorylation

E

The citric acid cycle. Carbon skeletons for amino acid biosynthesis are supplied by intermediates of the citric acid cycle. Which intermediate would supply the carbon skeleton for synthesis of a five-carbon amino acid (see the figure)? A. malate B. citrate C. isocitrate D. succinate E. α-ketoglutarate

E

The figure shows the electron transport chain. Which of the following is the combination of substances that is initially added to the chain? A. oxygen and protons B. NAD+, FAD, and electrons C. NADH, FADH2, and protons D. oxygen, carbon dioxide, and water E. NADH, FADH2, and

E

What fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle, if glucose is the sole energy source? A. all of it B. 1/6 C. 1/2 D. 1/3 E. 2/3

E

What is the purpose of beta oxidation in respiration? A. oxidation of glucose B. control of ATP accumulation C. oxidation of pyruvate D. feedback regulation E. breakdown of fatty acids

E

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs? A. NAD+ is oxidized. B. The electrons gain free energy. C. The cytochromes phosphorylate ADP to form ATP. D. ATP synthase pumps protons by active transport. E. The pH of the matrix increases.

E

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the A. reduction of NAD+. B. lowering of pH in the mitochondrial matrix. C. restoration of the NA+ /K+ balance across the membrane. D. formation of ATP. E. creation of a proton-motive force.

E

Where does glycolysis take place in eukaryotic cells? A. mitochondrial intermembrane space B. mitochondrial inner membrane C. mitochondrial outer membrane D. mitochondrial matrix E. cytosol

E

Where is ATP synthase located in the mitochondrion? A. outer membrane B. electron transport chain C. mitochondrial matrix D. cytosol E. inner membrane

E

Which of the following most accurately describes what is happening along the electron transport chain in the figure? A. Chemiosmosis is coupled with electron transfer. B. Energy of the electrons increases at each step. C. Molecules in the chain give up some of their potential energy. D. ATP is generated at each step. E. Each electron carrier alternates between being reduced and being oxidized.

E

Which of the following statements describes NAD+? A. NAD+ has more chemical energy than NADH. B. NAD+ is oxidized by the action of hydrogenases. C. NAD+ can donate electrons for use in oxidative phosphorylation. D. In the absence of NAD+, glycolysis can still function. E. NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.

E

Which one of the following is formed by the removal of a carbon (as ) from a molecule of pyruvate? A. citrate B. oxaloacetate C. glyceraldehyde-3-phosphate D. lactate E. acetyl CoA

E

Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy? A. The covalent bonds in organic molecules and molecular oxygen have more kinetic energy than the covalent bonds in water and carbon dioxide. B. The oxidation of organic compounds can be used to make ATP. C. The electrons have a higher potential energy when associated with water and CO2 than they do in organic compounds. D. The covalent bond in O2 is unstable and easily broken by electrons from organic molecules. E. 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).

E

products of the citric acid cycle

FADH2 + NADH + CO2 + ATP

What molecule produced during the citric acid cycle feeds into the electron transport chain?

FADH2. FADH2 is a reduced molecule and an electron donor.

Which statement is correct regarding how CO2 is delivered to rubisco in C3, C4, or CAM plants?

In C4 plants, CO2 is delivered via four-carbon organic acids. In C4 plants, CO2 is delivered via four-carbon organic acids synthesized in mesophyll cells where rubisco is inactive.

both C3 and C4 plants have the enzymes of the Calvin cycle. How are C4 plants more efficient than C3 plants at fixing carbon

In C4, plants, carbon fixation takes place in mesophyll cells, whereas the Calvin cycle takes place in bundle sheath cells

What is the role of plastocyanin in the Z-scheme model?

It shuttles electrons between the cytochrome complex and photosystem I. Plastocyanin protein forms a link between photosystem II and photosystem I. It is reduced by the cytochrome complex and then diffuses through the thylakoid lumen to donate electrons to photosystem I.

In the Z-scheme ____ is the initial electron donor and ____ is the final electron acceptor.

In the Z-scheme ____ is the initial electron donor and ____ is the final electron acceptor. Water becomes oxidized, releasing oxygen gas, and NADP+ becomes reduced, producing NADPH.

Where is the energy in a glucose molecule?

In the bonds

as electrons are passed through the system of electron carriers associated with photosystem II, they lose energy. What happens to this energy?

It is used to establish and maintain a proton gradient

What is the effect of cholesterol on the permeability of biological membranes?

It reduces fluidity in high temp and reduces rigidity in low temp

Why are fermentation reactions important for cells?

It regenerates NAD+ from NADH to keep glycolysis going in the absence of oxygen. Fermentation is unlikely to occur when oxygen is available as the final electron acceptor at the end of the electron transport chain.

which of the following statements about NAD+ is true

NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle

What are the electron carrier(s) in the Krebs cycle?

NADH and FADH2

What two molecules produced during the light-capturing reactions of photosynthesis are used in the Calvin cycle?

NADPH and ATP These two molecules are produced in the light-capturing reactions of photosynthesis and are used to provide energy and reducing power to convert carbon dioxide into sugar.

After 3-PGA is phosphorylated, it is reduced by _____

NADPH supplies the electrons that reduce the phosphorylated 3-PGA.

Is Krebs cycle regulated? If yes, how?

The citric acid cycle can be turned off at multiple points, via several different mechanisms of feedback inhibition. Reaction rates are high when ATP is scarce; reaction rates are low when ATP is abundant

what is the role of the inner and outer mitochondrial membrane

The inner membrane folds over many times and creates layered structures called cristae. The fluid contained in the mitochondria is called the matrix. The folding of the inner membrane increases the surface area inside the organelle. The outer membrane is the gateway to the mitochondrion, just like the cell membrane is for the cell.

What is the functional role of the inter‐membrane space?

The main function of mitochondrial intermembrane space is oxidative phosphorylation. Channel proteins called porins in the outer membrane allow free movement of ions and small molecules into the intermembrane space.

In fermentation _____ is reduced and _____ is oxidized.

The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+.

Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions? Hints

The γ-phosphate is the primary phosphate group on the ATP molecule that is hydrolyzed when energy is needed to drive anabolic reactions. Located the farthest from the ribose sugar, it has a higher energy than either the α- or β-phosphate.

When is the overall free energy change ΔG in a reaction most likely to be negative

When products have lower potential energy and higher entropy than reactants

What is a phospholipid?

a lipid that contains phosphorus and that is a structural component in cell membranes

What is an amphipathic lipid?

a liquid that contains both hydrophillic and hydrophobic portions

cytoskeleton

a network of protein filaments that helps the cell to maintain its shape

photorespiration is

a process involving the addition of oxygen to ribulose-1,5-biphosphate and the formation of the products 3-phosphoglycerate and 2-phosphoglycolate

What is a second messenger?

a small, nonprotein signaling molecule that elicits an intracellular response to the first messenger (the signaling molecule that arrived at the cell surface).

What is a desmosome?

a structure by which two adjacent cells are attached, formed from protein plaques in the cell membranes linked by filaments

In muscle cells, fermentation produces _____

lactate and NAD+

What cellular compartment will be more in cells that secrete large quantities of digestive enzymes?

lysosomes

only animal cells have:

lysosomes

what provides the cell with support and are a component of the cytoskeleton

microfilaments

cilia and flagella are composed of

microtubules

what directs the movement of molecules into and out of the cell

nuclear pore

ribosomes are manufactured by the

nucleolus

Describe the transport process across cell membrane in terms of different types of molecules (large, small, charged, polar, etc)

only small and nonpolar can pass unfacilitated. the others need active or passive transport

What is osmosis in terms of thermodynamics? Why osmosis occurs spontaneously?

osmosis is the diffusion of water. It resolves the concentration gradient.

What is the major regulatory enzyme for glycolysis?

phosphofructokinase

only prokaryotic cells have:

photosynthetic membranes, magnetite-containing structures, flagella and fimbriae, and the nucleoid (circular DNA)

What is the difference between plant ECM and mammalian ECM?

plant ECM is made of cellulose and it very rigid. in animals, it is made of polysaccharides

what is the major adaptive advantage of cellular respiration

produce adenosine triphosphate

Energized electrons from photosystem I are used to

reduce NADP+.

During the Calvin cycle, carbon dioxide is _____ to drive the formation of sugars.

reduced. Sugars are reduced compared to carbon dioxide. NADPH provides the reducing power.

as membrane proteins grow from ribosomes on the ------, the proteins are embedded into the rough ER membrane

rough ER

data suggest that rubisco makes up 10% of the total protein found in spinach leaves. research elucidating the structure of the rubisco shows that is has four active sites. Why, with four active sites, might there be such a large concentration of rubisco in plant matter

rubisco is a very slow enzyme; what it lacks in speed, it makes up in numbers

How does carbon fixation differ between C3 and C4 plants

rubisco is the primary enzyme that catalyzes carbon fixation in C3 plnats and phosphoenolpyruvate carboxylase can catalyze carbon fixation in C4 plants.

what stores calcium and plays a role in detoxification and lipid synthesis

smooth ER

cell wall

strong supporting layer around the cell membrane in plants, algae, and some bacteria

the ATP made during fermentation is generated by

substrate-level phosphorylation

In the citric acid cycle, ATP molecules are produced by _____

substrate-level phosphorylation. A phosphate group is transferred from GTP to ADP.

In glycolysis, ATP molecules are produced by _____.

substrate-level phosphorylation. A phosphate group is transferred from glyceraldehyde phosphate to ADP.

what is the role of a cell that contains an extensive smooth ER

synthesizes large quantities of lipids

What is the role of cytoskeletal proteins in changing cell shape or location or any type of cell movement?

the proteins provide 1. structural support and a framework for arranging and organizing organelles and other cell components 2. paths for moving vesicles inside cells 3. machinery for moving the cell as a whole through the beating of flagella or cilia, or through cell crawling

what is the role of the mitochondrial matrix

the solution enclosed within the inner membrane that contains the enzymes responsible for synthesizing ATP

Most of the enzymes of the Calvin cycle also function in other metabolic pathways. This should not be a surprising finding, because

there is a close relationship between carbohydrate synthesis and metabolic breakdown

How do amphipathic lipids organize in water?

they form structures whose hydrophobic ends are insulated away from water. ex. miscelles

what happens to ribosomes that synthesize proteins without ER signal sequences

they remain in the cytosol and release the proteins there

chromosomes

threadlike structures made of DNA molecules that contain the genes

What is the function of the nuclear pore complex?

traffic across the nuclear envelope occurs through the nuclear pore that has a multiprotein nuclear pore compex that serves as a gatekeeper small molecules can passively diffuse through the nuclear pore. larger molecules enter the nucleus only if they contain a specific molecular signal that directs them through the pore via nuclear transport proteins.

If you were to expose cells that are undergoing cellular respiration to a radioactive oxygen isotope in the form of O2, which of the following molecules would you expect to be radiolabeled?

water

the electrons of photosystem II are excited and transferred to electron carriers. From which molecule or structure do the photosystem II replacement electrons come.

water