Deck 5: Essential Concepts of Metabolism

Question 1

Oxidation is defined as the ________ while reduction is the ________ .

A) gain of electrons, loss of protons
B) loss of electrons, gain of protons
C) loss of electrons, gain of electrons
D) loss of protons, gain of protons

Answer 1

C

Question 2

A holoenzyme consists of

A) an apoenzyme plus a cofactor
B) an apoenzyme plus a coenzyme
C) a protein and non-protein component
D) all of the above

Answer 2

D

Question 3

Which of the following statements about enzyme inhibition is true?

A) most noncompetitive inhibitors bind to several different sites on an enzyme
B) enzymes become less efficient as temperatures drop because they begin to denature
C) noncompetitive inhibitors bind to a site other than the active site
D) most human enzymes have an optimum temperature below normal body temperature

Answer 3

C

Question 4

Chemoautotrophic bacteria obtain the energy they need from

A) the reactions of photosynthesis
B) sunlight
C) carbon dioxide in the atmosphere
D) chemical reactions in their cytoplasm

Question 5

Digestive reactions where large molecules are broken down into smaller ones is called:

A) metabolism
B) catabolism
C) biosynthesis
D) anabolism

Question 6

The synthesis of DNA,in which small nucleotides are joined together to make a single large molecule would be most correctly described as being a/n ________ reaction.

A) metabolic
B) anabolic
C) catabolic
D) cytobolic

Question 7

Animals (humans for example)are

A) photoautotrophs
B) photheterotrophs
C) chemoautotrophs
D) chemoheterotrophs

Question 8

Competitive inhibition of enzymes occurs when

A) the inhibitor binds to the active site of the enzyme
B) the inhibitor binds to the allosteric site of the enzyme
C) the inhibitor changes the shape of the enzyme
D) the inhibitor is acted upon by the enzyme

Question 9

Enzymes work by

A) lowering the energy of the reactants
B) raising the energy of the products
C) decreasing the activation energy of the reaction
D) increasing the activation energy of the reaction

Question 10

Organisms which get their carbon from other organisms are

A) autotrophs
B) chemotrophs
C) phototrophs
D) heterotrophs

Question 11

Which one of the following pairs is mismatched?

A) alcohol - fermentation
B) pyruvate - glycolysis
C) carbon dioxide - glycolysis
D) NADH - Krebs cycle

Question 12

An enzyme-substrate complex forms when substrate binds to an enzyme at the enzyme's ______ site.

A) catalytic
B) allosteric
C) operative
D) active

Question 13

Photoautotrophs obtain energy from

A) light and use carbon dioxide as a carbon source
B) organic molecules and use carbon dioxide as a carbon source
C) inorganic substances and use carbon dioxide as a carbon source
D) light and use inorganic substances as a carbon source

Question 14

Sulfa drugs bind to the active site of the enzyme which normally converts PABA to folic acid,preventing the production of folic acid and,eventually,purine synthesis. In this case,the sulfa drug is acting as a/n

A) allosteric inhibitor
B) competitive inhibitor
C) noncompetitive inhibitor
D) uncompetitive inhibitor

Question 15

Which statement is true about enzymes?

A) Enzyme catalyzed reactions would not go forward without their specific enzymes.
B) Most enzymes catalyze several different reactions.
C) Coenzymes are organic molecules while cofactors are inorganic molecules.
D) A holoenzyme is an apoenzyme that is missing its cofactor.

Question 16

Factors that affect the rate of enzyme catalyzed reactions include

A) temperature
B) pH
C) concentration of enzyme
D) all of the above

Question 17

Substrate level phosphorylation during glycolysis refers to

A) The transfer of phosphate groups from ATP to glucose
B) The transfer of phosphate groups from 1,3 diphosphoglyceric acid to ADP
C) The transfer of phosphate groups from phosphoenolpyruvic acid to ADP
D) The transfer of phosphate groups from ATP to ADP

Question 18

In glycolysis each molecule of glucose eventually produces ________ molecules of pyruvic acid.

A) one
B) two
C) three
D) four

Question 19

How does concentration affect enzyme-catalyzed reactions?

A) as the concentration of the product goes up the enzyme increases the rate it produces the product
B) concentration does not effect enzyme-catalyzed reactions because they are irreversible
C) at chemical equilibrium no net change in the concentration of the product or substrate occurs
D) the quantity of enzyme available usually controls the rate of a metabolic reaction.

Question 20

Which of the following is not a carrier molecule that carries hydrogen atoms or electrons in oxidative reactions?

A) Iron
B) FAD
C) Niacin
D) NAD

Question 21

Which of the following is true about glycolysis?

A) the net yield of ATP is two ATPs for each molecule of glucose
B) it provides cells with a relatively large amount of energy
C) four molecules of ATP are used in the initial phosphorylation steps
D) the ATP that is used up during glycolysis is not considered in calculating the net yield of ATP

Question 22

Electron transport chain

A) involves transfer of O₂ to electrons in the substrate
B) results in a net consumption of ATP
C) can be thought of as electrons acting as fish increasing in energy as they jump up a waterfall
D) none of the above

Question 23

The prokaryotic aerobic metabolism of glucose produces a total (net)of ________ molecules of ATP.

A) 24
B) 30
C) 34
D) 38

Question 24

The initial substrate molecule for the Krebs cycle is

A) pyruvic acid
B) acetyl-CoA
C) acetic acid
D) butanediol

Question 25

In aerobic respiration,the final electron acceptor is

A) water
B) oxygen
C) sulfur
D) coenzyme Q

Question 26

During glycolysis,electrons are initially transferred to

A) NAD
B) FAD
C) NADP
D) H₂O

Question 27

All of the following are electron acceptors for anaerobic respiration,except:

A) carbon dioxide
B) oxygen
C) nitrate ions
D) sulfate ions

Question 28

The first step in protein metabolism is the breakdown of proteins into

A) nucleotides
B) fatty acids
C) amino acids
D) coenzymes

Question 29

Each acetyl-CoA molecule will eventually produce ________ in the Krebs cycle.

A) four pairs of electrons
B) three molecules of NAD
C) one molecule of GTP
D) two molecules of pyruvic acid

Question 30

In the electron transport chain,the energy to make ATP comes directly from

A) FAD
B) NAD
C) both FAD and NAD
D) neither FAD nor NAD

Question 31

Organisms that can use oxygen for metabolic reactions but can also function in an environment devoid of oxygen are termed

A) aerobes
B) anaerobes
C) aerophiles
D) facultative anaerobes

Question 32

During the metabolism of fats,the product of beta-oxidation enters

A) glycolysis
B) the Krebs cycle
C) oxidative phosphorylation
D) electron transport chain

Question 33

Which statement about fermentation is true?

A) all fermentation of pyruvic acid always results in the same end product
B) all fermentation of glucose begins with pyruvic acid as a substrate
C) the same fermentation reaction produces both wine and cheese
D) none of the above

Question 34

The electrons transferred from acetyl groups in the Krebs cycle are transferred to

A) NAD only
B) FAD only
C) neither NAD and FAD
D) both NAD and FAD

Question 35

The end product of glycolysis is

A) fructose-1,6-diphosphate
B) 1,3 diphosphoglyceric acid
C) phosphoenolpyruvic acid
D) pyruvic acid

Question 36

Which reaction takes place in the mitochondrial matrix?

A) glycolysis
B) fermentation
C) Krebs cycle
D) electron transport

Question 37

Chemiosmosis

A) forms ATP
B) occurs in the cell membrane of prokaryotes
C) transfers electrons along transport chain and pumps protons out of membrane
D) all the above

Question 38

In fermentation reactions occurring in yeast to produce wine,two products of the reaction are __________ and _________

A) acid; hydrogen gas
B) hydrogen gas; propionic acid
C) ethyl alcohol; methane
D) carbon dioxide; ethyl alcohol

Question 39

How is ATP formed from the electron transport chain?

A) charge difference of outer and inner membrane gives motive force to generate ATP
B) nitrates are used as their final electron acceptor
C) the last step involves H₂O to be split into O₂
D) all of the metabolites enter the Krebs cycle

Question 40

Pyruvic acid is metabolized in the absence of oxygen during the process of

A) glycolysis
B) fermentation
C) oxidation
D) dark reactions

Question 41

In photosynthesis,light energy is used to

A) break down proteins
B) phosphorylate ADP to form ATP
C) metabolize glycerol
D) synthesize carbohydrates

Question 42

In photosynthesis,chemical energy is used to make organic molecules in the

A) light reaction
B) dark reaction
C) hydrolytic reaction
D) photophosphorylation reaction

Question 43

Which of the following statements about the Krebs cycle is false?

A) the only true substrate is acetyl-CoA.
B) ATP and NADPH are used to reduce carbon dioxide
C) many nutrients are degraded to products that can enter the Krebs cycle
D) GTP is generated

Question 44

Distinguish between aerobic and anaerobic respiration. Is fermentation aerobic or anaerobic respiration? Can you think of any advantage afforded to those microorganisms that can carry out fermentation?

Question 45

The initial breakdown of glucose in a eukaryotic cell takes place in

A) cytoplasm
B) golgi
C) nucleus
D) cell membranes

Question 46

Glucose is to photosynthesis as pyruvate is to

A) oxidative phosphorylation
B) glycolysis
C) fermentation
D) Krebs cycle

Question 47

What are chemoheterotrophs and how do they obtain energy? Name and describe two other ways microorganisms obtain energy. Why do you think so many different ways of obtaining energy evolved?

Question 48

The green sulfur and purple sulfur bacteria are capable of

A) carrying out photosynthesis
B) only obtaining energy from organic molecules
C) bypassing glycolysis for the Krebs cycle
D) metabolizing without enzymes

Question 49

Describe the chemical characteristics of enzymes and indicate why they are important in the metabolism of large molecules and how they determine which metabolic pathways occur in a cell.

Question 50

A metabolic pathway that is involved in both breakdown and synthetic reactions is properly termed

A) catabolic
B) amphibolic
C) metabolic
D) anabolic

Question 51

What is returned to chlorophyll in cyclic photophosphorylation that is not returned in noncyclic photoreduction?

A) ATP
B) light
C) energy
D) electrons

Question 52

Bioluminescent microbes

A) may have evolved to remove oxygen from the atmosphere
B) are often beneficiares of symbiotic relationships with a larger host, producing light in exchange for nutrients
C) often have the enzyme luciferase which catalyzes the oxidation reaction that emits light
D) all of the above

Question 53

A surfactant

A) lowers the surface tension at the bacterium's posterior end allowing Myxcoccus to glide
B) is metabolized to produce phosphoenolpyruvate
C) forms channels through the outer membrane
D) emits light as it returns to its unexcited state

Question 54

In algae,the dark reactions of photosynthesis occur

A) in the cell membrane
B) in the matrix of the mitochondria
C) in the stroma of the chloroplast
D) in the nucleus