Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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1.
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Which
of the following organisms do not have cell walls? a. | plants | c. | bacteria | b. | fungi | d. | animals | | | | |
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2.
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Which
of the following is NOT true of plasma membranes? a. | Folded membranes increase surface area for
efficiency. | b. | Folded membranes do not form compartments in the
cell. | c. | Endoplasmic reticulum is made up of folded
membranes. | d. | Ribosomes are sometimes attached to folded
membranes. | | |
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3.
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Folded membranes are an advantage to a cell because _____. a. | cell processes
can be more efficient | b. | the membranes provide a large surface
area | c. | the membranes
form interconnected compartments | d. | all of these | | |
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4.
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Who
concluded that all plants are made of living cells? a. | Virchow | c. | Schwann | b. | Hooke | d. | Schleiden | | | | |
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5.
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All
living things are made up of _____. a. | cells | c. | wastes | b. | cork | d. | cellulose | | | | |
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6.
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What
do electron microscopes use to focus and magnify an image? a. | glass
lenses | c. | electron
beams | b. | X rays | d. | light | | | | |
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7.
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Each
of the following is a main idea of the cell theory except _____. a. | all organisms
are composed of cells | b. | the cell is the basic unit of organization of
organisms | c. | all cells are similar in structure and
function | d. | all cells come from preexisting cells | | |
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8.
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The
scientist who first described living cells as seen through a simple microscope was
_____. a. | van
Leeuwenhoek | c. | Hooke | b. | Schleiden | d. | Schwann | | | | |
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9.
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One
advantage of electron microscopes over light microscopes is their _____. a. | size | c. | two-dimensional
image | b. | higher magnification | d. | use of live specimens | | | | |
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10.
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If a
cell contains a nucleus, it must be a(n) _____. a. | plant cell | c. | animal cell | b. | eukaryotic
cell | d. | prokaryotic
cell | | | | |
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11.
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In a
chloroplast, the stacks of membranous sacs are called _____. a. | stroma | c. | plastids | b. | grana | d. | thylakoid membrane | | | | |
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12.
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Because cells have a watery environment both inside and outside, the polar ends of the
phospholipids in the plasma membrane form ____ layers a. | several | c. | double | b. | mosaic | d. | single | | | | |
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13.
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The
fluid mosaic model describes a structure with ____. a. | polar layers on
the outside and nonpolar layer on the inside | b. | nonpolar layers
on the outside and a polar layer on the inside | c. | polar layers on
both inside and outside | d. | nonpolar layers on both inside and
outside | | |
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14.
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Because the phospholipid molecules and some proteins are free to move, the plasma
membrane is said to be a ____. a. | bilayer | c. | fluid mosaic | b. | solid | d. | fatty
acid | | | | |
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15.
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Which
of the following might be a result of a disease that causes a thickened plasma
membrane? a. | increased
movement of molecules entering the cell | b. | decreased movement of molecules within the
cell | c. | decreased
movement of molecules entering the cell | d. | increased movement of molecules leaving the
cell | | |
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16.
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A
cell's contents would be the same as its surrounds, were it not for ____. a. | plasmolysis | c. | phagocytosis | b. | selective permeability | d. | dynamic equilibrium | | | | |
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17.
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A
plasma membrane is made up of a(n) _____. a. | cholesterol layer | c. | lipid bilayer | b. | enzyme
bilayer | d. | protein
layer | | | | |
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18.
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Which
is not a way that Figure 7-2 is a model of cellular theory?
Figure
7-2 a. | bricks are small
units in a building | b. | bricks are solid | c. | there are many
bricks in a building | d. | bricks are organized to make a larger
unit | | |
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Figure 7-3
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19.
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What
is the approximate size of A in Figure 7-3? a. | 400 mm | c. | 700 mm | b. | 500 mm | d. | 1000 mm | | | | |
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20.
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What
is the approximate size of B in figure 7-3? a. | 400 mm | c. | 700 mm | b. | 500 mm | d. | 1000 mm | | | | |
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21.
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What
would be the best way to estimate the size of C in Figure 7-3? a. | increase
magnification | c. | estimate by what
you can see | b. | decrease magnification | d. | assume it is 2000 mm | | | | |
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Figure 7-4
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22.
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What
would happen to the structure in Figure 7-4 if part D is completely removed? a. | it would become
solid | c. | it would have
holes in it | b. | it would disintegrate | d. | it would collapse in on itself | | | | |
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23.
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What
structure is analogous to a sewage system?
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24.
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Where
are you least likely to find water in the structure shown in Figure 7-4
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25.
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Which
of the following pictures in Figure 7-5 most likely approximate the motion phospholipids make in a
plasma membrane?
Figure 7-5
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Figure 7-6
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26.
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Which
structure in Figure 7-6 is the cell control center?
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27.
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Which
structure in Figure 7-6 maintains homeostasis?
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28.
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Which
structure in Figure 7-6 is responsible for chemical reactions?
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29.
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Which
structure in Figure 7-6 transforms energy?
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30.
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Which
structure in Figure 7-6 sorts and transports?
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31.
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Which
parts of Figure 7-6 are in a prokaryotic cell? a. | D and M | c. | C and J | b. | A and
K | d. | G and
L | | | | |
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32.
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A
cell contains the structure shown in Figure 7-7. What other cell structure that is not found in all
eukaryotic cells is likely to be found in this cell?
Figure 7-7 a. | mitochondria | c. | cell wall | b. | ribosomes | d. | plasma
membrane | | | | |
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Completion
Complete each sentence or
statement.
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33.
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In a
cell, the sites of protein synthesis are the ____________________.
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34.
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The
small, membrane-bound structures inside a cell are ____________________.
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35.
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An
organism with a cell that lacks a true nucleus is a(n) ____________________.
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36.
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In a
cell, the breakdown of molecules in order to release energy occurs in the
____________________.
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37.
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Short, hairlike projections used for locomotion are
____________________.
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38.
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In
plants, the structures that transform light energy into chemical energy are called
____________________.
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39.
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The
pigment that gives plants their green color is ____________________.
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40.
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The
folded system of membranes that forms a network of interconnected compartments inside the cell is
called the _________________________.
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41.
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In a
cell, the tangles of long strands of DNA form the ____________________.
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42.
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The
functions of a eukaryotic cell are managed by the ____________________.
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Short Answer
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Figure 7-1
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43.
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Figure 7-1 shows a light area with no surrounding membrane in the center of the cell.
This area contains a single large DNA molecule. Would scientists classify this cell as a prokaryote
or a eukaryote? Explain.
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44.
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Identify the structures labeled A, B, and C in Figure 7-1.
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45.
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The
inner membrane of the mitochondria is folded many times. What advantage does this folding
provide?
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46.
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At
one time people believed that organisms could be formed spontaneously from nonliving matter. Evaluate
this belief in light of the cell theory.
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47.
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What
is the difference between an electron microscope and a compound microscope?
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48.
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Based
on what you know about cells, why are microscopes important to the study of cells?
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49.
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Between which cell types is the difference greater--plant and animal cells or
prokaryotic and eukaryotic cells? Give reasons for your answer.
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For
many years, scientists thought of the nucleus as "a bag of chromatin floating in a sea of
cytoplasm." Using electron microscopes, scientists saw that the nucleus was much more complex.
The nuclear envelope was two layered and covered with pores.
Scientists began further research. Scientist S punched small holes in the nuclear
envelope, allowing the contents to pour out. He observed that the nucleus retained its spherical
shape. From this, scientist S hypothesized that the nucleus had some other structural framework,
beyond the membrane itself. The next experiment performed by scientist S revealed that the nucleus
indeed had a fibrous protein framework, now called the nuclear matrix.
Three other scientists repeated this experiment, but each changed one part of it.
Scientist X used detergents and salt to remove the nuclear contents. Scientist Y used chemicals, and
scientist Z used enzymes. All three observed that a nuclear matrix remained.
Further electron microscopy revealed that the chromatin strands were anchored to a
fibrous layer that lines the inner layer of the nuclear envelope.
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50.
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Describe a procedure to determine whether the attachment of the chromatin to the
nuclear envelope is necessary for the chromatin to become chromosomes.
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51.
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Why
did scientists X, Y, and Z use different substances to remove the nuclear contents?
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52.
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What
was the variable in the experiments by scientists X, Y, and Z?
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53.
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Why
did scientists X, Y, and Z carry out their experiments?
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54.
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What
observation from scientist S's second experiment supported the original hypothesis?
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55.
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What
was the hypothesis of scientist S in his first experiment?
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In
the 1890s, E. Overton performed experiments to determine the structure of the plasma membrane. After
many years and various procedures, he determined that large, uncharged molecules enter a cell at a
rate proportional to their solubility in lipids. This observation was the first indication that the
plasma membrane is probably made up of lipids. Many scientists began to pursue the question of how
the lipids were arranged.
In 1925, two
Dutch scientists determined that the area covered by the lipids from a single red blood cell is twice
the area of the surface of the cell. From this, they reasoned that the cell is covered by a double
layer of lipid molecules. Based on this work, various scientists hypothesized that the membrane was
like a "fat sandwich" with two outer layers of protein on the surface of the lipid
layer.
None of the ideas seemed a satisfactory explanation
until microscopic studies of membranes prepared by a new technique of "freeze-fracture"
revealed that the proteins are actually embedded in the lipid layer. In 1972, on the basis on these
results and other evidence, two American scientists proposed the fluid-mosaic model.
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56.
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Why
was it almost 50 years between the Dutch scientists' research and the proposal of a fluid mosaic
model?
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57.
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What
model of the plasma membrane was based on the Dutch scientists' results?
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58.
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What
inference did the Dutch scientists make to reach their conclusion?
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59.
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What
conclusion did the Dutch scientists reach?
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60.
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The
result of one experiment often leads to further experiments. How do Overton's experiments illustrate
this fact?
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61.
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Is
Overton's hypothesis stated in the discussion above? If so, what was it?
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62.
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What
was the problem that Overton was trying to solve with his experiment?
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