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Worksheets1.2 Enzymes
Total questions: 19
Worksheet time: 10mins
Name
Class
Date
1.
Energy is commonly defined as "the capacity to do work." This definition is
a)
a. incorrect
b)
b. adequate in the physical sciences
c)
c. adequate in the biological sciences
d)
d. a clue to the actual properties of the concept
e)
e. not accepted by most scientists
2.
According to the first law of thermodynamics
a)
a. the energy of a system may increase if there is a corresponding decrease in energy elsewhere in the universe
b)
b. the amount of energy in the universe is constant
c)
c. chemical reactions do not create or destroy energy
d)
d. energy can change from one form to another
e)
e. all of these are true
3.
Which of the following statements is false?
a)
a. The universe has a specific amount of energy
b)
b. One form of energy can be converted to other forms of energy
c)
c. Whenever energy conversions occur, some energy is converted to less concentrated forms
d)
d. Once energy is utilized, it disappears
e)
e. There are differences in the quality of energy
4.
Which of the following is an application of the first law of thermodynamics?
a)
a. The level of entropy increases as time passes
b)
b. Living organisms represent an exception to the laws of energy
c)
c. The quantity of energy does not increase or decrease in the universe
d)
d. Fungi and plants do not make their own energy but derive it from somewhere else
e)
e. The amount of energy found in the compounds on one side of an equation is equal to that on the other side
5.
The activation energy of a reaction refers to the minimum amount of energy
a)
a. released by the reaction
b)
b. in the reactants
c)
c. in the products
d)
d. necessary to cause a reaction to proceed on its own
e)
e. difference between the energy of the reactants and the energy of the products
6.
CO2 and H2O will not form glucose on their own because
a)
a. CO2 does not contain sufficient energy
b)
b. H2O does not contain sufficient energy
c)
c. neither CO2 nor H2O contain sufficient energy
d)
d. the concentration of CO2 is too low in the atmosphere
e)
e. the bonds of CO2 and H2O are too stable to be broken without an input of energy
7.
Endergonic reactions
a)
a. result in products with less energy than the reactants
b)
b. require a net input of energy
c)
c. occur in the breakdown of glucose
d)
d. are used by cells to provide energy for biological reactions
e)
e. break down large molecules into smaller molecules
8.
Which of the following statements about exergonic reactions is false?
a)
a. They release energy
b)
b. Glucose metabolism is an example
c)
c. Their products have more energy than the reactants
d)
d. Some energy is converted to less biologically useful forms
e)
e. Bonds are broken
9.
Which of the following is NOT true of enzyme behavior?
a)
a. Enzyme shape may change during catalysis
b)
b. The active site of an enzyme orients its substrate molecules, thereby promoting interaction of their reactive parts
c)
c. All enzymes have an active site where substrates are temporarily bound
d)
d. Each enzyme can catalyze only a specific reaction
e)
e. Enzyme activity is not affected by pH and temperature
10.
Enzymes do not
a)
a. control the speed of a reaction
b)
b. change shapes to facilitate certain reactions
c)
c. may place physical stress on the bonds of the substrate
d)
d. always work on their own
e)
e. do all of these
11.
Which of the following statements is false?
a)
a. Enzymes catalyze reversible reactions in either direction
b)
b. Enzymes are highly specific
c)
c. Most enzymes are carbohydrate molecules
d)
d. Enzymes allow some reactions to occur that would never occur without them
e)
e. Enzymes may be temporarily modified during their involvement with the substrate
12.
The active site of an enzyme
a)
a. is where the coenzyme is located
b)
b. is a specific bulge or protuberance on an enzyme
c)
c. is a groove or crevice in the structure of the enzyme complementary to the substrate
d)
d. will react with only one substrate no matter how many molecules may resemble the shape of the substrate
e)
e. rigidly resists any alteration of its shape
13.
All of the following are factors in enzyme-catalyzed reactions that work alone or in combination to lower the activation energy EXCEPT
a)
a. helping substrates get together
b)
b. orienting substrates in positions favoring reaction
c)
c. breaking the laws of thermodynamics
d)
d. shutting out water molecules
e)
e. inducing a fit between enzyme and substrate
14.
An enzyme is thought to optimize the fit between substrates by restraining and stretching or squeezing them into certain shapes and moving them to the transition state as described by the ____ model of enzyme activity.
a)
a. lock and key
b)
b. induced-fit
c)
c. template
d)
d. activation
e)
e. conformational
15.
Which of the following statements is false?
a)
a. Enzymes are highly specific and act on chemicals called substrates
b)
b. Enzymes act as catalysts and speed up chemical reactions within cells
c)
c. Most enzymes work best under very low pH conditions
d)
d. Most enzymes are proteins
e)
e. Enzymes can become deactivated by high fevers
16.
Allosteric inhibition generally results from
a)
a. excess substrates
b)
b. binding of regulatory molecules at sites other than the active sites
c)
c. a change in the temperature of the system
d)
d. a lack of coenzymes
e)
e. changes in pH
17.
Allosteric enzymes
a)
a. have regions that bind with inhibitor or activator molecules
b)
b. are associated with important energy-carrying nucleotides
c)
c. are not affected by temperature or pH
d)
d. have two active sites
e)
e. have all of these
18.
Which of the following statements is true of metabolic pathways?
a)
a. They are enzyme-mediated sequences of reactions
b)
b. They may be biosynthetic or degradative
c)
c. Photosynthesis is a biosynthetic pathway
d)
d. Catabolism is a degradative pathway
e)
e. All of these statements are true
19.
A "high-energy bond" in ATP
a)
a. absorbs a large amount of free energy when the phosphate group is attached during phosphorylation
b)
b. is formed when ADP is phosphorylated to ATP
c)
c. is similar to the bonds in GTP
d)
d. contributes to the “energy in” part of some reactions
e)
e. is/does all of these
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