SKILL: Completing
Sentences
One reading skill is the ability to complete
an incomplete sentence by logically determining what will complete the unfinished
thought.
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Read the passage below, which covers topics from
your textbook. Answer the questions that follow.
Lipids are divided into categories according to
their structure. Three classes of lipids important to living things contain fatty acids:
triglycerides, phospholipids, and waxes. A triglyceride is composed of three molecules of
fatty acid joined to one molecule of the alcohol glycerol. Saturated triglycerides are composed of
saturated fatty acids. They typically have high melting points and tend to be hard at room
temperature. In contrast, unsaturated triglycerides are composed of unsaturated fatty acids and are
usually soft or liquid at room temperature.
Phospholipids have two,
rather than three, fatty acids joined to a molecule of glycerol. The cell membrane is composed of two
layers of phospholipids, which are referred to as the lipid bilayer. The inability of lipids
to dissolve in water allows the membrane to form a barrier between the inside and outside of the
cell. This bilayer arrangement of molecules produces a stable and effective barrier for a
cell.
A
wax is a type of structural lipid. A wax molecule consists of a long fatty-acid chain joined
to a long alcohol chain. Waxes are highly waterproof, and in plants, waxes form a protective coating.
Waxes also form protective layers in animals.
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1.
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Lipids are divided into categories according to
their .
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2.
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The three (3) classes of lipids are
.
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3.
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Saturated triglycerides are composed of
.
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4.
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At room temperature, unsaturated triglycerides
are .
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5.
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The two layers of phospholipids that
form the cell membrane are called the .
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6.
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Lipids cannot
dissolve in .
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7.
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The bilayer
arrangement of molecules in a cell membrane gives the cell a
.
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8.
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Waxes form a
protective coating on the outer surfaces of .
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SKILL:
Vocabulary Development
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Choose “B” on the line if the
statement describes triglycerides. Choose “C” on the line if the statement describes
phospholipids. Choose “A” on the line if the statement describes
waxes. a. | Waxes | b. | Triglycerides | c. | Phospholipids |
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9.
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They consist of a long fatty-acid chain joined to a long alcohol chain.
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10.
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Two categories of these are saturated and unsaturated.
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11.
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They consist of two molecules of fatty acids joined by a molecule
of
glycerol.
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12.
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Two layers of these enclose a cell.
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13.
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They consist of three molecules of fatty acids joined to one molecule
of
glycerol.
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14.
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They form a protective layer in animals.
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Essay
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15.
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Read the question and write your answer in the
space provided.
The prefix lipo- is derived from a Greek term
meaning “fat.” The suffix “-oid”
means
“resembling” or “having the appearance
of.” What can you infer about a substance
that is described as being lipoid?
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Multiple Choice: Choose the letter of the
phrase that best completes the statement.
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16.
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A main structural difference between the three categories of lipids is the
number of
a. | fattu acid present | c. | oxygen moelcules present | b. | alcohol molecules
present | d. | Both (a) and
(b) |
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