Deck 17: Metabolism: an Overview

Question 1

All are characteristics of anabolism EXCEPT:

A) assembly of complex molecules.
B) formation of new covalent bonds.
C) ATP provides energy.
D) NADPH is an electron donor.
E) all are true.

Answer 1

E

Question 2

Most organisms show ____ in their major pathways of metabolism.

A) marked similarity
B) some similarity
C) minimal similarity
D) considerable diversity
E) major diversity

Answer 2

A

Question 3

All are characteristics of metabolism EXCEPT:

A) a process which synthesizes either energy or complex cellular substances.
B) a process of intermediates.
C) the conversion of food energy into energy of motion.
D) a free-flow unregulated process.
E) a process responding to the momentary energy requirements of a cell.

Answer 3

D

Question 4

In the case of shared anabolic and catabolic pathways, the ____ serve as the points of regulation.

A) largest enzymes
B) ATP producing enzymes
C) NADH utilizing enzymes
D) rate-limiting enzymes
E) all are true

Question 5

Metabolon characteristics include all EXCEPT:

A) "units of metabolism".
B) discrete multienzyme complex.
C) soluble enzymes associated into stable multienzyme complexes.
D) membrane bound multienzyme systems.
E) all are characteristics.

Question 6

Which statement is most likely to be true concerning obligate anaerobes?

A) These organisms can use oxygen if it is present in their environment.
B) These organisms cannot use oxygen as their final electron acceptor.
C) These organisms carry out fermentation for at least 50% of their ATP production.
D) Most of these organisms are vegetative fungi.
E) None of the above.

Question 7

Likely the most ancient of the metabolic pathways in which energy is released from glucose and captured in the form of ATP under anaerobic conditions is called:

A) photooxidation.
B) oxidative phosphorylation.
C) citric acid cycle.
D) glycolysis.
E) none of the above.

Question 8

Solar energy is converted to the chemical energy of organic molecules by ____, and ____ recover this energy by metabolizing the organic substrates.

A) photoautotrophs; heterotrophs
B) heterotrophs; chemoautotrophs
C) chemoautotrophs; heterotrophs
D) photoautotrophs; chemoautotrophs
E) none are true.

Question 9

All are true about the relationship between catabolism and anabolism EXCEPT:

A) They occur simultaneously.
B) Products of one process provide substrates for the other.
C) They occur in many of the same organelles.
D) The generation of ATP by catabolism provides the energy required by anabolism.
E) Anabolism is endergonic while catabolism is exergonic.

Question 10

Which of the following is the major advantage of a multi-enzyme complex?

A) it's large size enables it to span an entire membrane
B) the product of one enzyme is passed directly to the next enzyme without the possibility of diffusion
C) multi-enzyme complexes are much less likely to be inhibited
D) all of the above
E) none of the above

Question 11

What are the final products of aerobic catabolism?

A) pyruvate and H₂O.
B) acetyl-CoA and CO₂.
C) CO₂ and H₂O.
D) pyruvate and acetyl-CoA.
E) ammonia and O₂.

Question 12

Since both glycolysis and gluconeogenesis are spontaneous pathways, which of the following explains how this is true?

A) glycolysis uses 10 enzyme catalyzed steps while gluconeogenesis uses 11
B) the three irreversible steps of glycolysis have alternate routes for gluconeogenesis
C) glycolysis converts glucose to pyruvate while gluconeogenesis converts pyruvate to glucose
D) glycolysis is oxidative while gluconeogenesis is reductive
E) glycolysis is catabolic while gluconeogenesis is anabolic

Question 13

What is the relationship between photoautotrophs and heterotrophic cells?

A) Photoautotrophs use light energy for synthesis of organic molecules while heterotrophs metabolize organic substances for fuel and building blocks.
B) photoautotrophs use organic compounds as a source of carbon while heterotrophs use CO₂ as a source of carbon.
C) Photoautotrophs synthesize CO₂ while heterotrophs synthesize O₂.
D) Heterotrophs convert solar energy into chemical energy while photoautotrophs break down organic molecules.
E) There is no relationship between the two.

Question 14

The definition of an amphibolic pathway is:

A) a pathway found in animals living in both land and water.
B) a pathway that is carried out both in water and organic solvents.
C) a pathway found on both sides of the mitochondrial membrane.
D) a pathway that is both anabolic and catabolic in nature.
E) all of the above.

Question 15

In phototrophs, ____ and ____ are the two energy-rich primary products from the transformation of light energy into chemical energy.

A) ATP; NAD⁺
B) NADPH; ATP
C) NADH; NADPH
D) ATP; NADH
E) ATP; NADH

Question 16

Photoheterotrophs require:

A) organic carbon sources and light.
B) carbon dioxide and light.
C) organic carbon sources and oxidation-reduction reactions.
D) carbon dioxide and inorganic compounds.
E) carbon dioxide and oxidation-reduction reactions.

Question 17

Which of the following statements is true regarding metabolic pathways?

A) catabolic pathways are generally reductive while anabolic pathways are generally oxidative
B) catabolic pathways use a wide variety of substrates to produce a small number of waste products.
C) an amphibolic pathway is extremely wasteful because it simultaneously operates as both an anabolic pathway and a catabolic pathway.
D) NAD⁺ is used as a reducing agent in catabolic pathways while NADPH is used as an oxidizing agent in anabolic pathways
E) none of the above

Question 18

All of the following are chemoheterotrophs EXCEPT:

A) Staphylococci aureus.
B) fungi.
C) algae.
D) animals.
E) non-photosynthetic roots.

Question 19

Some species can adapt to anaerobic conditions by substituting other electron acceptors for oxygen in their energy-producing pathways and are called:

A) aerobes.
B) obligate aerobes.
C) facultative anaerobes.
D) obligate anaerobes.
E) none of the above.

Question 20

Many of the catabolic pathways converge to the common two-carbon intermediate:

A) alanine.
B) acetyl group of acetyl-CoA.
C) lactic acid.
D) glucose.
E) carbon dioxide.

Question 21

In photosynthesis, NADPH is generated as light is used to oxidize ____ to ____.

A) water; O₂
B) water; CO₂
C) NADPH; O₂
D) water; NADP⁺
E) CO₂; NADPH

Question 22

One advantage of nuclear magnetic resonance (NMR) spectroscopy for the investigation of metabolism is that it utilizes:

A) radioisotopes.
B) specific metabolic inhibitors.
C) autoradiography.
D) non-invasive techniques.
E) none are true.

Question 23

When an individual has a ____ nitrogen balance, excess dietary protein is converted into ____.

A) negative; energy
B) positive; energy
C) negative; nucleic acids
D) positive; protein for storage
E) both b and d are true

Question 24

When dietary carbohydrate consumption exceeds the energy needs of the individual, excess carbohydrate is converted to ____ and ____ for energy storage.

A) amino acids; glucose
B) fructose; triacylglycerols
C) triacylglycerols; glycogen
D) glycogen; protein
E) none of the above.

Question 25

All of the following are a coenzyme or a precursor of a coenzyme EXCEPT:

A) thiamin.
B) riboflavin.
C) retinol.
D) niacin.
E) biotin.

Question 26

In prokaryotic cells, phospholipid synthesis and oxidative phosphorylation are carried out in:

A) plasma membranes.
B) cytosol.
C) mitochondria.
D) ribosomes.
E) endoplasmic reticulum.

Question 27

Excess carbohydrate and fat in the human diet is stored as triacylglycerols. The risk of which of the following would be increased in an individual who consistently consumes too much fat and carbohydrate?

A) atherosclerosis
B) heart disease
C) colon cancer
D) breast cancer
E) all of the above

Question 28

Which of the following statements regarding nutrition is FALSE?

A) Dietary protein is a source of essential amino acids
B) Organisms can produce all of the essential energy yielding nutrients and micronutrients needed
C) Complex carbohydrates can provide simple sugars for the glycolytic pathway
D) Essential fatty acids are components of biological membranes
E) Fiber is needed to help clear the digestive tract

Question 29

All are characteristics of coenzymes EXCEPT:

A) carry functional groups.
B) maintenance of original structure.
C) provide a broader range of catalytic properties.
D) can be derived from water-soluble vitamins.
E) can serve as an electron carrier.

Question 30

The dehydrogenase enzymes facilitate the direct transfer of hydride anion. Which of the following coenzymes is required for this transfer?

A) biotin
B) folic acid
C) lipoic acid
D) TPP
E) NAD⁺

Question 31

When carbohydrate intake is low, ____ are formed from acetate units to provide metabolic fuel for the ____ and other tissue.

A) fatty acids; liver
B) ketone bodies; brain
C) ketone bodies; liver
D) amino acids; brain
E) sterols; heart

Question 32

Energy is generally extracted from phototrophs and chemotrophs by:

A) hydrolysis reactions.
B) condensation-cleavage reactions.
C) oxidative-reduction reactions.
D) acid-base reactions.
E) phosphorylation reactions.

Question 33

The enzymes of glycolysis and those of the citric acid cycle are found in which cellular compartments in muscle cells?

A) both in the cytoplasm
B) glycolysis in cytoplasm and citric acid cycle in mitochondria
C) both in mitochondria
D) glycolysis in cytoplasm and citric acid cycle in lumen of the endoplasmic reticulum
E) both in the lumen of the endoplasmic reticulum

Question 34

Which of the following is a result of a high fat, high protein, low carbohydrate diet?

A) the bloodstream has a healthy level of ketone bodies
B) glycogen stores are close to maximum capacity
C) the brain operates most efficiently on this type of diet
D) ketone body production generally exceeds rate of elimination
E) none of the above

Question 35

A possible function of NADPH is to:

A) provide reducing equivalents to synthesize glucose from CO₂.
B) carry electrons from anabolic reactions.
C) provide a source of hydrogens for oxidative biosynthesis.
D) be reduced by hydride ions to form NAD⁺.
E) produce an oxidative product.

Question 36

All of the following are examples of energy transduction EXCEPT:

A) dehydrogenase catalyzed reactions
B) isomerase reactions
C) oxidative phosphorylation
D) NAD⁺- NADH shuttle
E) all of the above are correct

Question 37

From the following types of organic molecules, the order of most reduced to most oxidized is:
A)aldehyde
B)hydrocarbon
C)CO₂
D)alcohol
E)carboxylic acid

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

Question 38

Whcih of the following is NOT a characteristic of aerobic catabolic pathways?

A) an example of a catabolic pathway is the conversion of hexoses to 3-carbon compounds
B) ADP is phosphorylated to ATP as a result of such pathways.
C) NADH is a common product of such pathways
D) Water is oxidized to O₂
E) generally, the energy produced by such pathways is greater than the energy required to activate the substrates for the pathway

Question 39

All are coenzymes with an adenine nucleotide portion EXCEPT:

A) ATP.
B) NADH.
C) Coenzyme A.
D) FADH₂.
E) FMNH₂.

Question 40

Dehydrogenases are enzymes that:

A) move hydrogens within the molecule.
B) add hydrogens across double bonds.
C) transfer hydrogens between substrates.
D) transfer hydride ions to NAD⁺ (or NADP⁺) and release a proton.
E) all are true.

Question 41

Thioesters have higher ____ than that of oxygen esters.

A) mobility
B) electronegativity
C) resonance
D) positive ΔG
E) group transfer potential

Question 42

What vitamin is needed for coagulation of blood and what must happen for it to be functional?

A) vitamin D, a co-translational modification of serine.
B) vitamin K, a posttranslational carboxylation of glutamate.
C) vitamin K, a co-translational carboxylation of aspartate.
D) vitamin D, a posttranslational glycosylation of serine.
E) vitamin E, a posttranslational glycosylation of tyrosine.

Question 43

What are the principal minerals in the human body?

A) iron and chloride
B) sodium and potassium
C) calcium and sodium
D) calcium and phosphorus
E) sulfur and phosphorus

Question 44

What causes pyridoxal-5-phosphate (PLP) to be so versatile?

A) It reacts very quickly with simple sugars.
B) Its ability to be a one or two electron carrier.
C) The formation of a thioester bond.
D) Its ability to transfer methyl groups.
E) Its ability to form a Schiff base and act as an electron sink.

Question 45

Pantothenic acid is the vitamin portion of ____.

A) ATP
B) FAD
C) pyridoxal phosphate
D) Coenzyme A
E) TPP

Question 46

______ is often used in carboxylation reactions while ____ is often used in decarboxylation reactions.

A) thiamine pyrophosphate; lipoate
B) lipoate; biotin
C) biotin; thiamine pyrophosphate
D) pyridoxal-5-phosphate; biotin
E) lipoate; pyridoxal-5-phosphate

Question 47

Unsaturated fatty acids in membranes are particularly susceptible to ____ and vitamin E may provide protection because it is a potent ____.

A) oxidation; antioxidant
B) reduction; reducing agent
C) reduction; reducing agent
D) substitution; reactant
E) substitution; reactant

Question 48

What coenzyme is found in pyruvate decarboxylase that aids in the decarboxylation of α-keto acids?

A) Thiamine pyrophosphate
B) Folic acid
C) Biotin
D) Lipoic acid
E) none of the above

Question 49

The conversion of glucose-6-phosphate to glucose-1-phosphate has a ΔG´° of + 8.4 kJ/mol. How can a reaction such as this proceed in a cell?

A) it must be coupled to ATP hydrolysis
B) the product must be rapidly used in a subsequent step of the pathway
C) it can only occur with the help of an enzyme
D) this reaction can not proceed and must go in the reverse manner
E) both B and C are correct

Question 50

In a biotin-dependent carboxylation, _____ provides the energy for activation of ____.

A) acetyl CoA; carbon dioxide
B) ATP; lysine amine group
C) NADH; bicarbonate
D) ATP; bicarbonate
E) acetyl CoA; carboxyl group

Question 51

Pyruvate + CoA + NAD⁺ → ____ + CO₂ + ____

A) oxaloacetate; ATP
B) malonyl CoA; NADH + H⁺
C) methylmalonyl CoA; biotin
D) acetyl CoA; NADH + H⁺
E) succinyl CoA; NAD⁺

Question 52

The cofactors NAD⁺, NADPH and FAD all have what common chemical feature?

A) they all contain a guanine nucleotide
B) they all contain a sulfhydryl group that acts as a nucleophile
C) they all pick up or release two electrons during an oxidation/reduction reaction
D) they all can be used for phosphorylation of enzyme substrates
E) none of the above

Question 53

Pyridoxal-5-phosphate (PLP) is involved in all EXCEPT:

A) aminotransferases (transaminases).
B) α- and β-decarboxylations.
C) β- and γ-eliminations.
D) racemizations.
E) all of the above.

Question 54

Which vitamin is essential to vision?

A) A
B) C
C) D₂
D) B₁₂
E) B₁

Question 55

Retinol and the carotenoids follow the pathways of ____ digestion and absorption.

A) complex carbohydrates
B) proteins
C) simple sugars
D) nucleic acids
E) lipids

Question 56

Cholecalciferol is hydroxylated twice to form ____ that acts like a ____ to regulate ____ and ____ metabolism.

A) 24,25-hydroxyvitamin D; vitamin D-binding protein; calcium; chloride
B) ergosterol; vitamin D-binding protein; sodium; calcium
C) 7-dehydrocholesterol; hormone; calcium; phosphate
D) 1,25-dihydroxycolecarciferol; prehormone; sodium; phosphate
E) 1,25-dihydroxycolecarciferol; hormone; calcium; phosphate

Question 57

All of the coenzymes listed participate in electron transfer EXCEPT:

A) FAD.
B) biotin.
C) NAD⁺.
D) vitamin C.
E) lipoic acid.

Question 58

____ functions to couple acyl-group transfer and electron transfer during oxidation and decarboxylations of ____.

A) biotin; propionate
B) lipoate; propionate
C) lipoate; α-keto acids
D) TPP; α-keto acids
E) TPP; acetyl-CoA

Question 59

The statements are correct about the diseases caused by vitamin deficiencies EXCEPT:

A) niacin deficiency leads to gout.
B) vitamin A deficiency leads to night blindness that can be reversed by adding β-carotene to the diet.
C) vitamin B₁₂ prevents pernicious anemia.
D) vitamin D deficiency leads to demineralization of bones and rickets.
E) vitamin C prevents scurvy.

Question 60

What is a characteristic difference between FAD and NAD⁺?

A) NAD⁺ is a stronger oxidizing agent than FAD.
B) Only FAD participates in oxidation-reduction reactions.
C) NAD⁺ binds tightly to its enzyme while FAD only binds loosely.
D) NAD⁺ transfers two electrons while FAD can transfer one or two.
E) NAD⁺ is re-oxidized easily by molecular oxygen while FAD is not.

Question 61

Discuss the role of NADPH in anabolic processes.​

Question 62

Discuss fluxomics and the fluxome.​

Question 63

For the following reaction, what coenzyme is missing from the reactants?

A) FADH₂
B) NAD⁺
C) acetyl CoA
D) NADH
E) NADPH

Question 64

Discuss the classification of organisms based on their use of oxygen as an electron acceptor.​

Question 65

Explain the significance of carbohydrates.​

Question 66

Discuss an experiment that used heavy isotopes to elucidate a metabolic pathway.​

Question 67

What coenzyme would be required in the following reaction?

A) NAD⁺
B) thiamine pyrophosphate
C) biotin
D) lipoic acid
E) coenzyme A

Question 68

What coenzyme would be required in the following reaction?

A) ADP
B) thiamine pyrophosphate
C) biotin
D) lipoic acid
E) coenzyme A