AnswersFL-2000310-Biology 1 Sem 1 - FlexCatalysts

Catalysts — Unit test Answers

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1
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Which will increase the rate of a chemical reaction?

A
adding a catalyst
B
decreasing the pressure
C
decreasing the temperature
D
removing a catalyst
2
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Which statement about enzymes is true?

A
An enzyme functions to decrease the rate of a chemical reaction.
B
Enzymes are proteins that function as catalysts in nonliving things.
C
Each enzyme can catalyze many different biochemical reactions.
D
Enzymes and substrates fit together like a lock and key.
3

Which statement best describes the relationship between activation energy and rate of reaction?

A
Increasing the activation energy can increase the rate of a reaction.
B
Reducing the activation energy can increase the rate of a reaction.
C
Increasing the reaction energy does not alter the rate of reaction.
D
Reducing the activation energy can decrease the rate of a reaction.
4

The graph below compares the rates of reaction of a burning candle and an exploding firework.What can you conclude from the graph?

Question illustration
A
The reaction that causes a firework to explode requires less energy to start, and occurs more rapidly than the reaction that causes a candle to burn.
B
The reaction that causes a firework to explode requires less energy to start, and occurs less rapidly than the reaction that causes a candle to burn.
C
The reaction that causes a firework to explode requires more energy to start, and occurs less rapidly than the reaction that causes a candle to burn.
D
The reaction that causes a firework to explode requires more energy to start, and occurs more rapidly than the reaction that causes a candle to burn.
5

Which statement best describes how a catalyst can speed up a chemical reaction?

A
The catalyst decreases the activation energy needed.
B
The catalyst increases the concentration of products.
C
The catalyst binds to enzymes to release substrates.
D
The catalyst increases the concentration of reactants.
6

If the activation energy required for a chemical reaction were reduced, what would happen to the rate of the reaction?

A
The rate would increase.
B
The rate would decrease.
C
The rate would remain the same.
D
The rate would be zero.
7

Which two substances bind using a lock-and-key mechanism?

A
enzyme and substrate
B
reactant and substrate
C
substrate and product
D
reactant and product
8

Photosynthesis is an example of

A
an exothermic reaction.
B
an endothermic reaction.
C
a reaction that gives off heat.
D
a reaction that emits energy.
9

A researcher is designing a laboratory experiment to determine whether the inorganic substance A affects the rate of a reaction between two colored liquids, X and Y. When the reaction is complete, the liquid is clear. The reaction between X and Y is similar to one used by manufacturers to produce certain chemicals in factories.Which method would best answer his question about reaction rate and what will he find out about substance A?

A
First, he should measure the final temperature of the liquid when X and Y react without substance A. Then, he should measure the final temperature when he adds substance A to X and Y. He will find out if substance A is a catalyst.
B
First, he should measure how long it takes for the liquid to become clear if X and Y are mixed together. Then, he should measure how long it takes if he also adds substance A to X and Y. He will find out if substance A is a catalyst.
C
First, he should measure the final temperature of the liquid when X and Y react without substance A. Then, he should measure the final temperature when he adds substance A to X and Y. He will find out if substance A is an enzyme.
D
First, he should measure how long it takes for the liquid to become clear if X and Y are mixed together. Then, he should measure how long it takes if he also adds substance A to X and Y. He will find out if substance A is an enzyme.
10

How does a catalyst work?

A
by increasing the temperature of a chemical reaction
B
by decreasing the pressure of a chemical reaction
C
by increasing the concentration of reactants in a reaction
D
by decreasing the activation energy of a reaction
11

A substance that influences the reaction but does not participate in the reaction is a

A
catalyst
B
reactant
C
product
D
substrate
12

A student wants to create a liquid volcano. The student observes bubbles in the soft drink prior to opening it. The student first proceeds to open the soft drink bottle and place it on the floor.Next the student drops candy tablets into the drink at a continuous pace. The student notices a very powerful reaction in which the candies, still intact, are pushed out of the soda as the drink fizzes and starts to bubble.In this scenario, what would be the catalyst?

A
The candy tablets being added to the drink.
B
The gasses being released when the drink was first opened.
C
The liquid in the container.
D
The container that holds the liquid.
13

Which statement correctly describes a chemical reaction?

A
Reactants come out of a reaction.
B
Energy is always released.
C
Bonds between atoms break and reform.
D
Products go into a reaction.
14

Lactase and carbonic anhydrase are examples of what type of substance?

A
substrate
B
reactant
C
product
D
enzyme
15

Which is the best definition of activation energy?

A
the energy required to end a chemical reaction
B
the energy required to bind a substrate to an active site
C
the energy required to form or break the bonds of reactant molecules
D
the energy required to re-form bonds in product molecules
16

What is a substrate?

A
a molecule that acts as a catalyst
B
a place on the enzyme where the reaction occurs
C
a place on the product where the enzyme fits
D
a reactant that is catalyzed by an enzyme
17

Which statement best describes the amount of catalyst that remains at the end of a reaction?

A
More catalyst is present at the end than at the beginning of the reaction.
B
Less catalyst is present at the end than at the beginning of the reaction.
C
The amount of catalyst is the same at the end as at the beginning of the reaction.
D
The catalyst is consumed by the reaction, so none remains at the end of the reaction.
18

What must happen before a chemical reaction can begin?

A
The activation energy must be exceeded.
B
The activation energy must be reached.
C
The concentrations of products and reactants must be equal.
D
The concentration of reactant molecules must be reduced.
19

Which component is released from the active site of an enzyme during a chemical reaction?

A
reactant
B
product
C
substrate
D
protein
20

The lock-and-key mechanism refers to

A
the complementary shapes of an enzyme and a substrate.
B
the attractive forces between an enzyme and a substrate.
C
the ability of an enzyme to lower the activation energy of a reaction.
D
the ability of an enzyme to “unlock” the products of a reaction.

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