Deck 14: Enzymes As Biological Catalysts

Question 1

What does lactase do?

A) metabolizes lactose into carbon dioxide and water
B) hydrolyzes lactose into smaller sugars, glucose and galactose
C) synthesizes lactose in the body
D) removes lactose from the body

Answer 1

B

Question 2

The purpose of an enzyme is to

A) transport nutrients through the body.
B) provide structure, such as hair or cell walls.
C) speed the rate of a chemical reaction.
D) transport oxygen throughout the body.

Answer 2

C

Question 3

Which of the following describes reaction energy?

A) the energy difference between the reactants and transition state
B) the energy difference between the transition state and products
C) the energy possessed by the reactants
D) the energy difference between the products and reactants

Answer 3

D

Question 4

Activation energy is the energy input that is required to form the

A) reactants.
B) transition state.
C) products.
D) all of the above

Question 5

In the reaction CH₃Br + OH^- $\rightarrow$ CH₃OH + Br^-, what is the hypothesized shape of the transition state?

A) tetrahedral
B) trigonal planar
C) trigonal bipyramidal
D) octahedral

Question 6

In the reaction CH₃Br + OH- $\rightarrow$ CH₃OH + Br^-, what is the shape of the CH₃Br?

A) tetrahedral
B) trigonal planar
C) trigonal bipyramidal
D) octahedral

Question 7

A catalyst increases the rate of a chemical reaction by

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

Question 8

What is the substance produced by the catalytic converter in your car when carbon monoxide, CO, passes through it?

A) methane, CH₄
B) carbonate, CO₃^2-
C) carbon dioxide, CO₂
D) carbon, C

Question 9

What is the catalyst coating on the inside of a catalytic converter?

A) activated carbon
B) stainless steel
C) transition metals
D) magnesium

Question 10

Why are the transition metals good catalysts?

A) They can form positive ions.
B) They react readily with carbon monoxide.
C) They can readily change oxidation state and absorb other substances on to their surface and activate them toward other reactions.
D) They are good conductors of heat.

Question 11

The catalytic activity of an enzyme occurs where?

A) at the cofactor
B) at the active site
C) on the substrate
D) anywhere on the enzyme

Question 12

What are most enzymes?

A) metal ions
B) vitamins
C) minerals
D) proteins with a specific structure

Question 13

What substance does lactase use to catalyze the hydrolysis of lactose?

A) H₂O
B) HCl
C) H₂O₂
D) NaOH

Question 14

What is missing in people who are lactose intolerant?

A) vitamin K
B) lactase
C) bacteria in their intestines
D) protease

Question 15

What causes the production of lactase in people who are lactose tolerant?

A) The transcription factor does not bind to the promoter site.
B) The transcription factor binds to the promoter site.
C) The mRNA carrying the gene can't leave the cell nucleus.
D) An incorrect amino acid is used during translation.

Question 16

What historical event may have selected for people who are lactose tolerant?

A) raising cows and goats to make cheese
B) hunting for meat
C) famine causing dairy farmers to drink milk
D) farming grains, such as wheat and barley

Question 17

What are ribozymes?

A) protein enzymes
B) RNA enzymes
C) DNA enzymes
D) substance that translates amino acids into protein enzymes

Question 18

Alpha Centauri is a star that is 4.37 light-years away. A rocket ship travelling at the speed of light would require 2,300,000 minutes to reach the star. If the rocket ship traveled at a speed 1 million times faster than the speed of light, how many minutes would it take the rocket ship to reach Alpha Centauri?

A) 2.3 minutes
B) 2300 minutes
C) 0.23 minutes
D) 23 minutes

Question 19

An auxiliary molecule that some enzymes require to carry out their function is called a(an)

A) substrate.
B) cofactor.
C) active site.
D) transition state.

Question 20

In the induced-fit model of the enzyme function, what is changing shape?

A) the substrate only
B) the enzyme only
C) both the substrate and enzyme
D) neither the substrate or enzyme

Question 21

How does gene-culture co-evolution explain lactase persistence in some adult populations in the world?

A) It was an advantage to be lactose tolerant to consume cheese.
B) Milk which was drunk in times of famine caused a mutation in the lactase gene.
C) Adults who were able to consume milk survived better in famines and so had a selective advantage.
D) Over time some populations developed bacteria in the gut that consume lactose.

Question 22

Why are lactose intolerant people incapable of producing lactase?

A) The gene that expresses lactase is missing.
B) Transcription factor binds to the promoter site and does not express lactase.
C) Transcription factor does not bind to the promoter site and does not express lactase.
D) The RNA that is transcribed from the lactose gene fails to translate amino acids into lactase.

Question 23

Lactase persistence is the

A) ability of babies and infants to produce lactase.
B) inability of adults to produce lactase.
C) switch from being able to produce lactase to not producing lactase.
D) the ability for some adults to produce lactase.

Question 24

How does lactose intolerance vary in global geography?

A) Lactose intolerance is common in people in all parts of the globe.
B) Lactose intolerance is common in Northern Europe.
C) Lactose intolerance is common in East Asia.
D) Lactose intolerance is not common in any part of the globe.

Question 25

Activation energy refers to what energy in the reaction pathway?

A) the energy of the reactants
B) the difference in energy between the transition state and the products
C) the difference in energy between products and reactants
D) the difference in energy between the transition state and the reactants.

Question 26

A catalyst affects which energy?

A) the energy of the reactants
B) the energy of the products
C) the reaction energy
D) the activation energy

Question 27

Which energy is required to be input to complete a reaction?

A) the energy of the reactants
B) the energy of the products
C) the reaction energy
D) the activation energy

Question 28

The catalyst in the catalytic converter accelerates the rate of the reaction C≡O + O=O $\rightarrow$ O=C=O + O. How does it accomplish this?

A) It mixes carbon monoxide and oxygen.
B) It creates a turbulent mixing of carbon monoxide and oxygen.
C) It raises the temperature of the carbon monoxide and oxygen.
D) It lowers the energy barrier between the carbon monoxide/oxygen reactants and the carbon dioxide/oxygen products.

Question 29

According to the naming convention, which of the following is likely an enzyme?

A) amylose
B) amylase
C) galactose
D) amyloid

Question 30

Other than proteins, what other biochemical may act as a catalyst?

A) DNA
B) polysaccharides
C) vitamins
D) RNA

Question 31

Which of the following is a correct assumption made for the lock-and-key model of enzymes?

A) Both the enzyme and substrate are flexible in shape.
B) The enzyme is flexible while the substrate shape is rigid.
C) Both the enzyme and substrate are rigid in shape.
D) The substrate shape is flexible while the enzyme shape is rigid.

Question 32

A catalyst is consumed or altered when it is used in a chemical reaction.

Question 33

A catalyst can accelerate hundreds, thousands, or millions of individual reactions.

Question 34

A transition metal catalyst speeds up reactions more than an enzyme.

Question 35

All people carry the gene to produce lactase.

Question 36

An enzyme speeds up reactions billions or trillions of times greater than a metal catalyst.

Question 37

The shape of the active site on the enzyme determines the binding of the substrate.

Question 38

Enzymes are more selective in which substrates they bind than metal catalysts.

Question 39

Two very similar molecules that differ only in being chiral, such as D- or L-, will always bind similarly to an enzyme.

Question 40

People who are lactose intolerant cannot digest cheese which contains no lactose.

Question 41

Milk contains the protein lactase.

Question 42

A reaction component with higher potential energy is more stable.

Question 43

The energy barrier between reactants and products in a reaction is ____________________.

Question 44

The stages by which reactants are transformed into products is called ____________________.

Question 45

In the reaction of methyl bromide and hydroxide the orientation of the C-H bonds flips. This is called ____________________.

Question 46

The binding of substrate to an enzyme is the ____________________ model.

Question 47

The binding of a substrate to a catalyst where both components change shape is the ____________________ model.

Question 48

Catalysts operate through a series of steps called the ____________________.

Question 49

The sugars glucose and galactose are joined in lactose by ____________________ bonds.

Question 50

Describe the transition state for the reaction of methyl bromide and hydroxide.

Question 51

How does a catalyst lower the activation energy of a chemical reaction?

Question 52

Describe the steps of a catalytic cycle.

Question 53

What are the four complementary functional group interactions between the enzyme and substrate?

Question 54

Explain why you can't increase temperature to speed up a biological reaction.

Question 55

How is an enzyme capable of catalyzing more than one cycle of a reaction pathway?

Question 56

Explain how the induced-fit model of the enzyme allows the enzyme to catalyze reactions millions of times faster than a metal catalyst.

Question 57

Why would so few adults in East Asia be lactose tolerant?

Question 58

The Inuit, indigenous people of the Arctic, rely on fish, sea mammals, and land animals for food. Would you expect them to be lactose tolerant or lactose intolerant?

Question 59

What causes the symptoms experienced by lactose intolerant people who consume milk?

Question 60

Why are enzymes so highly selective in which substrates they bind?