Deck 28: Biosynthetic Pathways

Question 1

How will the body respond if a normal biosynthetic pathway is blocked?

A) The body will develop a different and completely new pathway to replace the blocked pathway.
B) The body will not be able to produce the compounds of the blocked pathway and will eventually die.
C) The body will use the reverse of the degradation pathway to make the necessary compounds.
D) The body will not be affected by the blockage of a biosynthetic pathway.

Answer 1

C

Question 2

How does the presence of excess inorganic phosphate affect phosphorylase-catalyzed glycogen synthesis?

A) It favors the hydrolysis of glycogen and the production of glucose-1-phosphate.
B) It prevents the hydrolysis of glycogen and increases cross-linking in glycogen.
C) It enhances the rate of glycogen synthesis.
D) It enhances the rate of glycogen breakdown.

Answer 2

A

Question 3

Which of the following enzymes catalyzes the dark reactions of photosynthesis?

A) RuBisCo
B) succinate dehydrogenase
C) lactate dehydrogenase
D) peroxidase

Answer 3

A

Question 4

Which of the following pathways are called biosynthetic pathways?

A) anabolic pathways
B) catabolic pathways
C) both anabolic and catabolic pathways
D) neither anabolic nor catabolic pathways

Question 5

Identify a reactant in the light reactions of photosynthesis.

A) carbon dioxide
B) water
C) both carbon dioxide and water
D) neither carbon dioxide nor water

Question 6

Which of the following enzymes catalyzes only the reactions of gluconeogenesis?

A) hexokinase
B) phosphoglycerate kinase
C) pyruvate kinase
D) pyruvate carboxylase

Question 7

Which of the following statements is true of ATP usage in gluconeogenesis and glycolysis?

A) ATP is consumed during both gluconeogenesis and glycolysis.
B) ATP is produced during both gluconeogenesis and glycolysis.
C) ATP is consumed during gluconeogenesis and produced during glycolysis.
D) ATP is produced during gluconeogenesis and consumed during glycolysis.

Question 8

During photosynthesis, how many molecules of oxygen are produced per molecule of glucose synthesized?

A) one
B) four
C) six
D) twelve

Question 9

Which of the following pigments is required for the synthesis of glucose by photosynthesis?

A) hemoglobin
B) myoglobin
C) chlorophyll
D) none of these

Question 10

Identify a product of the light reactions of photosynthesis.

A) glucose
B) molecular oxygen
C) both glucose and molecular oxygen
D) neither glucose nor molecular oxygen

Question 11

Which of the following compounds is required to add a unit of glucose to a glycogen molecule?

A) ADP-glucose
B) ATP-glucose
C) UDP-glucose
D) UTP-glucose

Question 12

Identify a product of the dark reactions of photosynthesis.

A) glucose
B) molecular oxygen
C) both glucose and molecular oxygen
D) neither glucose nor molecular oxygen

Question 13

Which of the following statements is true of anabolic and catabolic pathways?

A) Both of these are biosynthetic pathways.
B) Both of these are biodegradation pathways.
C) Anabolic and catabolic pathways are biosynthetic and biodegradation pathways, respectively.
D) These are completely identical and non-flexible pathways.

Question 14

Identify a pathway that involves the reduction of carbon dioxide to carbohydrates in the presence of NADPH coenzymes.

A) glycolysis
B) gluconeogenesis
C) the Calvin cycle
D) the Cori cycle

Question 15

Identify a reactant in the dark reactions of photosynthesis.

A) carbon dioxide
B) water
C) both carbon dioxide and water
D) neither carbon dioxide nor water

Question 16

Which of the following cell organelles contain photosynthetic pigments?

A) mitochondria
B) chloroplasts
C) nuclei
D) lysosomes

Question 17

Identify a pathway in which glucose is synthesized in the body from the intermediates of the glycolytic and citric acid pathways.

A) glycolysis
B) the Calvin cycle
C) gluconeogenesis
D) the Cori cycle

Question 18

Which of the following metabolic cycles utilizes lactate as the starting material for gluconeogenesis?

A) the Calvin cycle
B) the citric acid cycle
C) the Cori cycle
D) the Krebs cycle

Question 19

Which of the following amino acids can serve as the starting material for gluconeogenesis?

A) glucogenic amino acids
B) ketogenic amino acids
C) both glucogenic and ketogenic amino acids
D) neither glucogenic nor ketogenic amino acids

Question 20

Which of the following are the starting materials of photosynthesis?

A) CO₂ and H₂O
B) SO₂ and O₂
C) N₂O and O₂
D) none of these

Question 21

How does malonyl-CoA inhibit the -oxidation of a fatty acid?

A) by inhibiting the activity of acetyl-CoA synthase
B) by inhibiting the activity of carnitine acyltransferase
C) by promoting the activity of acetyl-CoA synthase
D) by promoting the activity of carnitine acyltransferase

Question 22

Which of the following is a pair of essential fatty acids?

A) linoleic acid and oleic acid
B) linoleic acid and linolenic acid
C) linolenic acid and oleic acid
D) oleic acid and stearic acid

Question 23

Which of the following nucleotides activates choline to complete the synthesis of phosphatidylcholine?

A) ATP
B) CTP
C) GTP
D) UTP

Question 24

Identify the process that involves the conversion of glucose into glycogen.

A) glycolysis
B) gluconeogenesis
C) glycogenesis
D) glycogenolysis

Question 25

Identify the product formed by the sequential condensation of three acetyl-CoA molecules during cholesterol synthesis.

A) HMG-CoA
B) acyl-CoA
C) succinyl CoA
D) malonyl-CoA

Question 26

Which of the following fatty acids is present in the membranes of the human eye?

A) palmitic acid
B) myristic acid
C) stearic acid
D) docosahexaenoic acid

Question 27

Which of the following products is formed when a glycerol-1-phosphate molecule reacts with two molecules of acyl CoA?

A) a choline molecule
B) a citrate molecule
C) a phosphatidate molecule
D) a triphosphate molecule

Question 28

Which of the following molecules is the source of carbon during fatty acid synthesis?

A) acetate
B) acetyl-CoA
C) malate
D) succinyl CoA

Question 29

Which of the following compounds is the starting material for the Cori cycle?

A) lactate
B) malate
C) oxaloacetate
D) pyruvate

Question 30

Why are dietary cholesterol and cholesterol synthesized in the liver not available for forming synapses?

A) They are consumed by various parts of the body before they reach the brain.
B) They cannot cross the blood-brain barrier because they are present as LDL.
C) Both of these statements are valid reasons.
D) Neither of these statements is a valid reason.

Question 31

Which of the following enzymes controls the rate of cholesterol synthesis?

A) cholinesterase
B) HMG oxidase
C) HMG-CoA reductase
D) mevalonate decarboxylase

Question 32

Which of the following statements is true of the degradation and synthesis of fatty acids?

A) Both fatty acid synthesis and degradation occur in the cytoplasm.
B) Both fatty acid synthesis and degradation occur in mitochondria.
C) Fatty acid degradation occurs in the cytoplasm, whereas fatty acid synthesis mostly occurs in the mitochondria.
D) Fatty acid degradation occurs in the mitochondria, whereas fatty acid synthesis mostly occurs in the cytoplasm.

Question 33

In which organ does the Cori cycle take place?

A) the intestine
B) the liver
C) the muscles
D) the spleen

Question 34

Which of the following chemical bonds is present in acetyl-ACP?

A) a disulfide bond
B) a thioether bond
C) a thioester bond
D) a thiol bond

Question 35

Which of the following oxidizing agents is required to convert saturated fatty acids to unsaturated fatty acids?

A) FADH₂
B) FADPH₂
C) NADH
D) NADPH

Question 36

Which of the following is the longest saturated fatty acid that can be synthesized by the ACP merry-go-round mechanism?

A) arachidonic acid
B) lauric acid
C) palmitic acid
D) stearic acid

Question 37

Identify a process for the breakdown of fatty acids.

A) glycolysis
B) gluconeogenesis
C) β-oxidation
D) deamination

Question 38

Which of the following chemical bonds is present in ACP?

A) a disulfide bond
B) a thioether bond
C) a thioester bond
D) a thiol bond

Question 39

Which of the following reactions occurs when a saturated fatty acid is converted to an unsaturated fatty acid?

A) a condensation reaction
B) a hydrolysis reaction
C) an oxidation reaction
D) a reduction reaction

Question 40

How many high-energy phosphate anhydride bonds are present in UTP?

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

Question 41

Of the 20 amino acids that are found in human proteins, how many are nonessential amino acids?

A) 5
B) 10
C) 15
D) 20

Question 42

Which of the following coenzymes is required for the synthesis of glutamate from α-ketoglutarate?

A) FAD
B) FADH₂
C) NADH
D) NAD⁺

Question 43

Which of the following amino acids cannot be synthesized from glutamate?

A) alanine
B) asparagine
C) serine
D) tyrosine

Question 44

Of the 20 amino acids that are found in human proteins, how many are essential amino acids?

A) 5
B) 10
C) 15
D) 20

Question 45

In which of the following diseases does the body break down its own proteins?

A) kwashiorkor
B) multiple sclerosis
C) rickets
D) none of these

Question 46

How does prenylation affect a protein?

A) It makes a protein more hydrophilic.
B) It makes a protein more hydrophobic.
C) It causes a protein to become fixed in the lipid bilayer of a membrane.
D) It prevents a protein from participating in signal transduction.

Question 47

Which type of reaction occurs when α-ketoglutarate is synthesized from glutamate?

A) reductive amination
B) reductive deamination
C) oxidative amination
D) oxidative deamination

Question 48

Which of the following amino acids is needed in the synthesis of membrane lipids?

A) cysteine
B) glycine
C) serine
D) threonine

Question 49

What is an essential amino acid?

A) an amino acid that is present in the primary structure of all proteins
B) an amino acid that is necessary for a protein to adopt a proper secondary or tertiary structure
C) an amino acid that cannot be synthesized by the human body and must be supplied in the diet
D) none of these

Question 50

Which of the following cholesterol-lowering drugs was sold under the trade name "Lipitor"?

A) mevastatin
B) lovastatin
C) atorvastatin
D) fluvastatin

Question 51

Which of the following compounds undergo condensation to produce cholesterol?

A) two farnesyl pyrophosphates
B) two geranyl pyrophosphates
C) a farnesyl pyrophosphate and a geranyl pyrophosphate
D) none of these

Question 52

Which of the following compounds form the structural units of farnesyl pyrophosphate and geranyl pyrophosphate?

A) alkaloids
B) alkanes
C) isoprenes
D) none of these

Question 53

Which of the following statements is true of farnesyl pyrophosphate and geranyl pyrophosphate?

A) They are the precursors of cholesterol biosynthesis.
B) They are intermediates in cholesterol biosynthesis.
C) They are structural isomers of each other.
D) None of these statements is correct.

Question 54

How do statin drugs lower cholesterol levels in the body?

A) by breaking down excess cholesterol in the plasma
B) by competitively inhibiting the enzyme HMG-CoA reductase
C) by enhancing the removal of cholesterol through urine
D) by causing excess cholesterol to be stored in the liver

Question 55

Which of the following amino acids can be synthesized from glutamate?

A) asparagine
B) cysteine
C) tyrosine
D) valine

Question 56

Which of the following statements is true of the two hydroxyl groups in mevalonate?

A) Both the groups are primary alcohols.
B) One group is a primary alcohol and the other group is a secondary alcohol.
C) One group is a primary alcohol and the other group is a tertiary alcohol.
D) Both the groups are secondary alcohols.

Question 57

Identify an essential amino acid that the bodies of growing children do not synthesize in sufficient quantities.

A) histidine
B) proline
C) serine
D) tyrosine

Question 58

Consider the following reaction sequence. In which of the following metabolic pathways does the given reaction sequence occur?

A) gluconeogenesis
B) glycolysis
C) glycogenesis
D) glycogenolysis

Question 59

Identify an essential amino acid that the bodies of growing children do not synthesize in sufficient quantities.

A) alanine
B) arginine
C) proline
D) serine

Question 60

Which of the following statements defines prenylation?

A) It is a step of cholesterol synthesis that involves the condensation of isoprene units.
B) It is the process by which multiple isoprene units bind to a protein to make it hydrophobic.
C) Both these statements define prenylation.
D) Neither of these statements defines prenylation.

Question 61

Consider the following reaction sequence. Which of the following statements is true of this reaction sequence?

A) It is a step in a process called glycogenesis.
B) It occurs within the mitochondrial matrix.
C) It can also occur in the absence of nucleotides.
D) All of these statements are true.

Question 62

Which of the following statements is true of anabolic pathways?

A) They use the intermediates of the citric acid cycle as substrates.
B) They use ATP as an energy source.
C) They use the reducing power of NADH and FADH₂.
D) All of these statements are true.

Question 63

Consider the following diagram of a chloroplast. Which of the following is not a similarity between chloroplasts and mitochondria?

A) Both chloroplasts and mitochondria contain the green pigment chlorophyll.
B) Both chloroplasts and mitochondria contain iron-sulfur complexes.
C) Both chloroplasts and mitochondria contain proton-translocating ATPases.
D) Both chloroplasts and mitochondria utilize a proton gradient for ATP synthesis.
E) None, they are similar to each other in all of aspects.

Question 64

Consider the following reaction sequence. Which statement is true of the product formed in the second step of the given reaction sequence?

A) It is called glycogen.
B) It is an example of a polysaccharide.
C) It can have from 30,000 to 120,000 molecules of glucose.
D) All of these statements are true.

Question 65

The cellular concentration of which compound determines the fate of fats?

A) malonyl-CoA
B) acetyl-CoA
C) succinyl CoA
D) acyl CoA

Question 66

What is the central metal ion in a chlorophyll molecule?

A) Ca⁺²
B) Cu⁺²
C) Mg⁺²
D) Mn⁺²

Question 67

Examine the following chemical reaction. Which of the following statements is true of this reaction?

A) Alanine is one of the products of the given reaction.
B) This reaction is an example of a deamination reaction.
C) The product of this reaction is an essential amino acid.
D) All of these statements are true.