Deck 5: Essential Concepts of Metabolism

Question 1

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 centered around the use of inorganic substances

Answer 1

D

Question 2

Substrate-level phosphorylation during glycolysis refers to the transfer of phosphate groups from:

A)ATP to glucose
B)1,3 diphosphoglyceric acid to ADP
C)phosphoenolpyruvic acid to ADP
D)ATP to ADP

Answer 2

B

Question 3

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

A)Cytochrome
B)FAD
C)Niacin
D)NAD⁺

Answer 3

C

Question 4

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 organic substances as a carbon source

Question 5

Sulfa drugs bind to the active site of the enzyme which normally converts para-amino benzoic acid (PABA)to folic acid,preventing the production of folic acid and,eventually purine synthesis. In this case,the sulfa drug is acting as a/an:

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

Question 6

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 7

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.

Question 8

Competitive inhibition of enzymes occurs when the inhibitor:

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

Question 9

A holoenzyme can consist 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

Question 10

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

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

Question 11

Organisms which get their carbon from other organisms are:

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

Question 12

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 13

Degradation reactions where large molecules are broken down into smaller molecule is referred to as:

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

Question 14

Animals (humans for example)are:

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

Question 15

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 16

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

Question 17

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 affect 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 18

Factors that affect the rate of enzyme catalyzed reactions include:

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

Question 19

Which one of the following pairs is mismatched?

A)Alcohol - Fermentation
B)Pyruvate - Glycolysis
C)Carbon dioxide - Glycolysis
D)Oxaloacetic acid - Krebs cycle

Question 20

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 21

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

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

Question 22

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

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

Question 23

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 24

Chemiosmosis:

A)forms ATP
B)occurs in the cell membrane of prokaryotes
C)uses a proton gradient to activate ATP synthase
D)all the above

Question 25

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 26

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

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

Question 27

Which statement about fermentation is true?

A)All fermentation of pyruvic acid always results in the same end product.
B)All fermentation starts with glucose going through glycolysis.
C)The same fermentation reaction produces both wine and cheese.
D)None of the above

Question 28

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 29

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

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

Question 30

In aerobic respiration,the final electron acceptor is:

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

Question 31

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 32

How is ATP formed by chemiosmosis?

A)Proton gradient across a membrane provides motive force
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 33

Which reaction takes place in the mitochondrial membrane?

A)Glycolysis
B)Fermentation
C)Krebs cycle
D)Electron transport chain

Question 34

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

A)FADH₂
B)NADH
C)both FADH₂ and NADH
D)neither FADH₂ nor NADH

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

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 37

During glycolysis,electrons are initially transferred to:

A)NAD⁺
B)FAD
C)NADP
D)H₂O

Question 38

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

A)four pairs of electrons
B)three molecules of NADH
C)one molecule of GTP
D)all of these choices

Question 39

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

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

Question 40

The initial substrate molecule for the Krebs cycle is:

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

Question 41

As electrons are passed from carrier to carrier,their energy changes.At which point in the chain would you expect the energy of the electrons to be the highest?

A)A
B)B
C)C
D)D
E)E

Question 42

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 43

In algae,the dark reactions of photosynthesis occur in the:

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

Question 44

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 45

Glucose is to photosynthesis as pyruvate is to:

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

Question 46

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 47

At which temperature do enzymes begin to denature?

A)20 degrees Celsius
B)30 degrees Celsius
C)40 degrees Celsius
D)50 degrees Celsius

Question 48

A surfactant:

A)lowers the surface tension at the bacterium's posterior end allowing Myxococcus 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 49

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 50

In photosynthesis,light energy is used to:

A)break down proteins
B)phosphorylate ADP to form ATP
C)synthesize carbohydrates
D)two of these choices

Question 51

The initial breakdown of glucose in a eukaryotic cell takes place in the _____.

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

Question 52

Compare anaerobic and anaerobic respiration in terms of energy yields and reactants within the pathways. Anaerobic respiration and fermentation are both pathways that may occur in the absence of oxygen. Which confers a greater advantage to the cell? Why is the less advantageous pathway in existence within cells at all?"

Question 53

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

A)ATP
B)Light
C)Energy
D)Electrons

Question 54

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

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

Question 55

As electrons are passed from carrier to carrier,their energy changes.At which point in the chain would you expect the energy of the electrons to be the lowest?

A)A
B)G
C)C
D)F
E)E

Question 56

Bioluminescent microbes:

A)may have evolved because of aerobic metabolism
B)are often beneficiaries 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