Chapter 2: Chemistry of Life

Chapter 2: Chemistry of Life
1.
A)
B)
C)
D)
Ans:
The smallest unit of matter is the
molecule.
atom.
compound.
isotope.
B
2.
A)
B)
C)
D)
Ans:
An element is any substance that contains one type of
molecule.
isotope.
atom.
proton.
C
3.
A)
B)
C)
D)
Ans:
Organic compounds always contain ___________ atoms.
water
carbon
nitrogen
oxygen
B
4.
A)
B)
C)
D)
Ans:
The subunit molecules for proteins are
atoms.
amino acids.
enzymes.
polymers.
B
5.
A)
B)
C)
D)
Ans:
The positively charged particles in the nucleus of an atom are
neutrons.
electrons.
protons.
isotopes.
C
6.
A)
B)
C)
D)
Ans:
In the reactions that occur in metabolism, enzymes function as
amino acids.
lipids.
catalysts.
compounds.
C
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7.
A)
B)
C)
D)
Ans:
The most abundant molecule in living organisms is
water.
glucose.
oxygen.
saline.
A
8.
A)
B)
C)
D)
Ans:
Compounds that form ions when put into water are called
mixtures.
solvents.
electrolytes.
suspensions.
C
9.
A)
B)
C)
D)
Ans:
Molecules form because of
the shape of the individual atoms.
the attraction between electrons.
transfer or sharing of electrons.
a drive toward solubility.
C
10.
A)
B)
C)
D)
Ans:
An ion is an atom or molecule that
is in a gaseous state.
carries an electrical charge.
is attracted to a north-seeking pole.
forms a visible glow.
B
11.
A)
B)
C)
Ans:
The lower the pH,
the greater the hydrogen ion concentration.
the more acidic the solution.
Both of the choices are correct.
C
12.
A)
B)
C)
D)
E)
Ans:
The pH of the blood is slightly basic. Which of the following describes this pH?
6.4
4.6
4.7
7.4
13.8
D
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13.
A)
B)
C)
D)
Ans:
The differences between one polypeptide and another lies in
the type of peptide bond they contain.
the type of sugar they contain.
whether they are saturated or not.
the sequence of amino acids.
D
14. Which arrow in the following equation represents dehydration?
A) arrow 1
B) arrow 2
Ans: A
15.
A)
B)
C)
D)
Ans:
Glycogen is
a monosaccharide used for quick energy.
a protein found in cell membranes.
a polysaccharide used as stored energy.
a fat found in margarine.
C
figure 2.1
16.
A)
B)
C)
D)
Ans:
Which letter in figure 2.1 would you associate with a polypeptide?
a
b
c
d
C
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17.
A)
B)
C)
D)
Ans:
At which letter in figure 2.1 would it be appropriate to show the production of water?
a
b
c
d
B
18.
A)
B)
C)
D)
E)
Ans:
Organic compounds that are always insoluble in water are called
sugars.
lipids.
nucleotides.
proteins.
All of these choices are correct.
B
19.
A)
B)
C)
D)
Ans:
Which of the following contains glucose?
protein
fat
nucleic acid
starch
D
20.
A)
B)
C)
D)
Ans:
Which of the following is a nucleic acid?
DNA
RNA
both DNA and RNA
None of the choices are correct.
C
21.
A)
B)
C)
D)
Ans:
Which of the following is the main ingredient of fiber in our diet?
glycogen
protein
cellulose
lipid
C
22.
A)
B)
C)
D)
E)
Ans:
Which of the following contains high-energy phosphate bonds?
DNA
glycogen
RNA
ATP
phospholipids
D
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23. Explain how hydrogen bonding contributes to the characteristics of the water molecule.
Ans: Hydrogen bonding occurs between the negative (oxygen) and positive (hydrogen) sides
of adjacent water molecules. Hydrogen bonding makes water molecules cohesive so
water does not boil or freeze easily. Hydrogen bonding between water molecules and
ions also makes water a powerful solvent.
24. Explain the difference between an ionic bond and a covalent bond.
Ans: An ionic bond is formed when oppositely charged ions are attracted to one another; a
covalent bond is formed when atoms share electrons.
25. What is the significance of buffers?
Ans: They are substances or compounds that prevent large changes in the pH of a solution.
26. Explain how enzymes are essential to the body's homeostasis.
Ans: Enzymes are proteins that function as organic catalysts that speed up chemical reactions.
They are necessary for the chemical working of the cells and the body.
27. Explain the structure and function of ATP.
Ans: ATP is composed of the base adenine, the sugar ribose, and three phosphate groups and
is used in body cells to fuel synthetic reactions, active transport, nerve impulse
conduction, and muscle contraction.
28. If you need quick energy, would you eat foods high in carbohydrates, fats, or proteins?
Why?
Ans: Carbohydrates. They are the quickest and most readily available energy source for the
body.
29. Explain the difference between an isotope and an ion.
Ans: Isotopes are forms of a single element with different numbers of protons. Ions are forms
of a single element with different numbers of electrons.
30. Compare and contrast glycogen, starch, and cellulose regarding structure, function, and
nutritional value.
Ans: All three of these molecules are polymers of glucose. Glycogen is a glucose storage
form that is synthesized in the liver. Starch is a glucose storage form in plants and is an
important source of glucose in our diet. Cellulose is also formed by plants but is not
digestible by humans. Cellulose is an important source of fiber in the diet.
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31. Describe each of the three subatomic particles with regard to charge, weight, and
location in an atom.
Ans: Protons are positively charged particles with a weight of one atomic mass unit that are
located in the nucleus of an atom. Neutrons are uncharged particles with a weight of
one atomic mass unit that are also found in the nucleus of an atom. Electrons are
negatively charged particles with no appreciable weight that are located in the electron
shells that surround the nucleus of an atom.
32. Phosphorus has an atomic number of 15 and an atomic weight of 31. How many
protons, neutrons, and electrons does an atom of the element phosphorus have?
Ans: Phosphorus has 15 protons, 16 neutrons, and 15 electrons.
33. What is the relationship between the dissociation of water and the pH scale?
Ans: When water molecules dissociate they release hydrogen ions and hydroxide ions. In
pure water, the numbers of these ions are equal at 10–7. The values of the pH scale
represent hydrogen ion concentrations and the central value of the scale, which
represents a neutral pH, is 7. This is the negative of the exponent of the value for the
number of hydrogen ions in water.
34. How are ATP and DNA similar?
Ans: ATP is a nucleotide with a sugar, a base, and three phosphate groups. DNA is a nucleic
acid that is composed of nucleotides. Each nucleotide in DNA has a sugar, a base, and
one phosphate group.
35.
A)
B)
C)
D)
Ans:
Low levels of radiation are commonly used to:
sterilize dental products.
destroy cancer cells.
produce images of body parts.
All of these choices are correct.
C
36. Which of the following types of reactions involves the production of a larger product by
combining smaller reactants?
A) degradation
B) replacement
C) synthesis
D) Both replacement and synthesis are correct.
Ans: D
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37.
A)
B)
C)
D)
Ans:
Which type of chemical bond forms when atoms share pairs of electrons?
covalent
hydrogen
ionic
Both convalent and hydrogen are correct.
A
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