Deck 1: An Overview of Cells and Cell Research

Question 1

RNA is believed to have been the original genetic system because it can

A) form a stable double helix with a complementary nucleic acid strand.
B) catalyze the polymerization of nucleotides into another RNA strand.
C) form ribosomes.
D) transfer amino acids to ribosomes.

Answer 1

B

Question 2

The initial importance of membrane-enclosing, self-replicating RNA molecules and associated proteins was that they

A) maintained these molecules as a unit capable of reproduction and evolution.
B) provided sites for proteins to function.
C) transported materials in and out of the compartment.
D) kept other molecules out of the compartment.

Answer 2

A

Question 3

Stanley Miller applied electric sparks to a reducing atmosphere of methane, ammonia, water, and hydrogen, and the resulting products showed that under these conditions,

A) amino acids can form.
B) nucleotides can form.
C) amino acids can polymerize into polypeptides.
D) nucleotides can polymerize into nucleic acids.

Answer 3

A

Question 4

Which energy-producing process is thought to have come first during cellular evolution?

A) Photosynthesis
B) Glycolysis
C) Oxidative phosphorylation
D) Proteolysis

Question 5

At the time life arose on Earth, Earth's atmosphere contained abundant amounts of all of the following except

A) H₂.
B) N₂.
C) O₂.
D) H₂S.

Question 6

Organisms that evolved the ability to use H₂O as a donor of electrons and hydrogen for the photosynthetic conversion of CO₂ to organic compounds radically changed Earth by producing

A) sugar.
B) cellulose.
C) H₂.
D) O₂.

Question 7

The feature that most clearly distinguishes eukaryotes from prokaryotes is the presence of _______ in eukaryotic cells.

A) ribosomes
B) oxidative phosphorylation
C) RNA molecules
D) a nucleus

Question 8

Cytoplasmic organelles are

A) absent in prokaryotic cells and present in eukaryotic cells.
B) present in both prokaryotic and eukaryotic cells.
C) present in prokaryotic cells and absent in eukaryotic cells.
D) absent in both prokaryotic and eukaryotic cells.

Question 9

The eukaryotic nucleus contains _______ DNA molecule(s).

A) a single linear
B) a single circular
C) multiple linear
D) multiple circular

Question 10

The bacterial genome is located in a portion of the cell called the

A) nucleus.
B) nucleolus.
C) mesosome.
D) nucleoid.

Question 11

Eukaryotic cell nuclei contain genes that are

A) primarily of bacterial origin.
B) primarily of archaebacterial origin.
C) partly archaebacterial and partly bacterial in origin.
D) all of eukaryotic origin.

Question 12

Organelles such as mitochondria and chloroplasts are thought to have originated in eukaryotic cells via a process called

A) phagocytosis.
B) endosymbiosis.
C) endocytosis.
D) exocytosis.

Question 13

Mitochondria and chloroplasts resemble bacteria in that they

A) have their own DNA.
B) have their own ribosomes.
C) reproduce by simple division into two.
D) All of the above

Question 14

Which of the following is a colonial organism closely related to the evolutionary precursors of present-day plants?

A) Paramecium
B) Dictyostelium discoideum
C) Volvox
D) Arabidopsis thaliana

Question 15

The human body is composed of more than _______ different types of cells.

A) 100
B) 200
C) 400
D) 2,000

Question 16

E. coli is a useful model system for molecular biology studies because

A) it has a small genome.
B) it reproduces rapidly.
C) mutants can easily be isolated from culture dishes.
D) All of the above

Question 17

A yeast cell divides in culture about every

A) 20 minutes.
B) 40 minutes.
C) 2 hours.
D) 12 hours.

Question 18

How many genes does the haploid yeast nuclear genome contain?

A) 1,000
B) 6,000
C) 10,000
D) 20,000

Question 19

The adult nematode worm Caenorhabditis elegans consists of _______ somatic cells.

A) 95
B) 959
C) 1,500
D) 9,590

Question 20

The simplicity and clarity of Caenorhabditis elegans allowed researchers to

A) trace the developmental lineages of all cells in the adult.
B) identify the genes involved in differentiation of each cell type.
C) observe the process of fertilization better than had been possible in the past.
D) follow the process by which cell aggregation forms a multicellular organism.

Question 21

Drosophila melanogaster was an organism of choice for the study of

A) the process of fertilization.
B) the process of cell aggregation to form a multicellular organism.
C) the process of development.
D) mammalian genetics.

Question 22

Studies on which model organism led to the initial discovery of important mechanisms controlling the development of the animal body plan?

A) Mice
B) Drosophila melanogaster
C) Xenopus laevis
D) Yeast

Question 23

Arabidopsis thaliana is a model organism for studying the molecular biology of

A) plants.
B) fungi.
C) fruit flies.
D) vertebrates.

Question 24

Which fish is proving to be a useful model organism for the study of vertebrate development?

A) Zebrafish
B) Goldfish
C) Salmon
D) Guppy

Question 25

Cultures grown from cells of a dissociated tissue are called

A) primary cell cultures.
B) transformed cell lines.
C) normal cell lines.
D) secondary cell cultures.

Question 26

Most laboratories make use of cultured cells to study human disease. What makes these cultured cells such useful models?

A) Cells only function when they are not organized into tissues.
B) Cells cultured in the lab behave exactly the same as cells in the human body.
C) Cells are very inexpensive to grow.
D) They provide a continuous and uniform source of new cells.

Question 27

Viruses are useful model systems for studying

A) tooth development.
B) cell signaling.
C) DNA replication.
D) regulation of cell cycle control.

Question 28

The light microscope was used to observe the cellular structure of cork by _______, who named the chambers "cells."

A) Schleiden and Schwann
B) Hooke
C) Virchow
D) Leeuwenhoek

Question 29

The diffraction limited resolution of a standard light microscope is determined by which equation?

A) R = 0.61λNA
B) R = 0.61NA / λ
C) R = 0.61λ / NA
D) R = 0.61 / λNA

Question 30

Living cells are commonly visualized by means of _______ microscopy.

A) phase-contrast
B) bright-field
C) fluorescence
D) electron

Question 31

Fluorescent-labeled antibodies are used on cells primarily to locate a specific

A) DNA sequence.
B) RNA sequence.
C) protein.
D) carbohydrate.

Question 32

A common use of green fluorescent protein (GFP) is to

A) label antibodies.
B) visualize proteins in living cells.
C) photobleach other fluorescent proteins.
D) label DNA sequences.

Question 33

Which of the following experimental approaches would be useful for studying protein-protein interactions within a cell?

A) Differential interference-contrast microscopy
B) Differential centrifugation
C) Fluorescence pulse field gel electrophoresis (FPFGE)
D) Fluorescence resonance energy transfer (FRET)

Question 34

In fluorescence photobleaching experiments, recovery time is defined as the amount of time it takes the bleached area to regain its fluorescence. The recovery time for a cell with fluorescently labeled membrane proteins is

A) longer than the recovery time for a cell with fluorescently labeled lipids because lipids diffuse faster than proteins.
B) shorter than the recovery time for a cell with fluorescently labeled lipids because proteins diffuse faster than lipids.
C) equal to the recovery time for a cell with fluorescently labeled lipids because proteins and lipids diffuse at the same rate.
D) shorter than the recovery time for a cell with fluorescently labeled lipids because lipids diffuse faster than proteins.

Question 35

Super-resolution light microscopes extend the resolution limits of light microscopy to

A) 0.2 to 0.5 mm.
B) 0.2 to 0.5 μm.
C) 20 to 100 nm.
D) 20 to 100 Å.

Question 36

Electron microscopes have a resolution advantage over light microscopes because

A) electron microscopes allow the viewer to examine living cells.
B) electron microscope lenses have a larger numerical aperture.
C) electron microscopes are easier to use.
D) the wavelength of electrons is shorter than that of light.

Question 37

Specific proteins can be localized in the transmission electron microscope by use of

A) positive staining.
B) negative staining.
C) fluorescent-labeled antibodies.
D) gold-labeled antibodies.

Question 38

The method by which cell components are separated by centrifugation at progressively higher speeds is called _______ centrifugation.

A) differential
B) velocity
C) density-gradient
D) equilibrium

Question 39

Which of the following cell components will be concentrated in the first pellet produced by differential centrifugation?

A) Mitochondria
B) Nuclei
C) Endoplasmic reticulum
D) The cytosol

Question 40

It is generally believed that Earth's original cell enclosed a self-replicating _______ molecule.

Question 41

RNA, unlike DNA, is capable of _______ a number of different chemical reactions.

Question 42

The common source of electrons in the conversion of CO₂ into organic molecules in photosynthesis is _______.

Question 43

The two major groups of prokaryotic cells are the _______ and the _______, which diverged early in evolution.

Question 44

The DNA in a bacterium is located in a region termed the _______.

Question 45

The cell lineage that eventually became the plants acquired _______before acquiring _______.

Question 46

The amoeba _______ exists as a unicellular organism in abundant nutrient conditions and forms multicellular fruiting bodies in starvation conditions.

Question 47

_______ cells cover the surface of internal organs in the body, such as the intestine.

Question 48

Short generation time is one of the major factors that support using yeast or _______ for many fundamental molecular genetics experiments.

Question 49

Model systems serve as simplified examples in which the properties and development of cells can be examined easily. For mammals, a common model system is _______, and _______ is a common model for plants.

Question 50

Model systems such as Caenorhabditis elegans, Drosophila melanogaster, and zebrafish are especially useful for studying problems in cell differentiation and developmental biology because, in contrast to single cells such as E. coli and yeast, they are _______ systems.

Question 51

_______ cells, the most commonly used cell line, were derived from a biopsy of a tumor carried by Henrietta Lacks.

Question 52

Viruses have proven to be useful tools with which to explore the properties of cells and complex processes such as cancer because viruses are dependent on _______ processes for much of their replication and metabolism.

Question 53

_______ is a light microscope technique for studying the interaction of proteins.

Question 54

In the _______ microscope, imaging is restricted to a single focal plane by the use of an aperture pinhole to reject out of focus light; whereas in the _______ microscope, the same outcome is achieved through the use of light wavelengths such that excitation of the fluorescent dye requires the simultaneous absorption of two or more photons.

Question 55

In transmission electron microscopy, objects are imaged by their differences in _______ density.

Question 56

Similarities in basic metabolic mechanisms indicate that all present-day cells on Earth descended from a single primordial ancestor.

Question 57

Most of the genes of the bacterial symbionts that evolved into mitochondria are now found in the nucleus.

Question 58

Eukaryotes contain a mixture of genes from eubacteria and archaebacteria.

Question 59

Photosynthesis first evolved in the green algae.

Question 60

Compared to humans, E. coli has about a thousand times less DNA.

Question 61

Higher plants and higher animals are similar in that they contain about the same number of different cell types.

Question 62

Epithelial cells form sheets that cover the surface of the animal body and line internal organs.

Question 63

In good culture conditions, E. coli typically divides every two hours.

Question 64

Yeasts are simple eukaryotes.

Question 65

Caenorhabditis elegans is an important organism for the study of plant development.

Question 66

Studies on Arabidopsis thaliana have indicated that the mechanisms that control development in plants are completely different from those that control development in animals.

Question 67

The frog Xenopus laevis is useful for studying early development because its eggs are small and clear.

Question 68

Xenopus laevis, an amphibian vertebrate, is useful for developmental studies because when its eggs are fertilized, the embryos develop outside its body.

Question 69

A single somatic animal cell in culture is capable of forming an entire animal.

Question 70

Normal human fibroblasts can be grown only for 50-100 doublings in culture, after which they stop growing and die.

Question 71

Immortal cell lines are cells that can continue to proliferate in culture for an indefinite number of generations.

Question 72

A single immortalized fibroblast in culture is capable of forming an entire human.

Question 73

With appropriate stimulation, mammalian stem cells in culture can give rise to individual mammalian cell types and hence may provide a source of patient-specific replacement cells.

Question 74

Viruses are complexes of nucleic acid and protein that can replicate on their own.

Question 75

Viruses can have either RNA or DNA for their genetic material.

Question 76

Synthesis of DNA from RNA was first observed using retroviruses.

Question 77

Robert Hooke first coined the term "cell" following his observation, with a light microscope, of the pattern of cell walls in cork.

Question 78

Because the wavelength of electrons is 100,000 times shorter than the wavelength of visible light, the resolution of the electron microscope is 100,000 times better than the resolution of the light microscope.

Question 79

Scanning electron microscopy is usually used for a three-dimensional view of the surface of cells.

Question 80

Freeze fracture splits lipid bilayers and allows examination of the distribution of proteins that span the bilayer.