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may be a distinct entity or a building block of a more complex organism.
. Darwin noted that all populations have _______ potential to grow, but that in nature most populations _______ over time.
a group of morphologically similar organisms capable of interbreeding.
The nature and diversity of life have changed over time.
. Earth is approximately _______ years old.
It is thought that the process by which some prokaryotes were consumed by, then integrated into, other prokaryotes took place about _______ years ago.
c. all conversions of matter and energy taking place in an organism.
13. The initial accumulation of oxygen in the atmosphere was the result of photosynthesis from an organism most like modern
14. A prerequisite for the survival of life on land was the accumulation of
15. The chemical formula for ozone is
16. Ozone is important to life on Earth because it
c. blocks much ultraviolet radiation.c. blocks much ultraviolet radiation.
17. Most _______ must obtain their energy from the sun.
18. Plants are
a. eukaryotic, multicellular photosynthesizers.
19. When biologists organize species into groups, they attempt to do so based on
d. degree of relatedness.
20. Scientists group species on an evolutionary tree based on
the fossil record.
b. physical structures.
c. gene similarities.d. All of the above
21. Domain Eukarya includes
b. Kingdom Plantae.
c. Kingdom Fungi.
d. Kingdom Animalia.
e. All of the above
22. An evolutionary tree
a. shows evolutionary relationships.
b. places the most closely related groups on the same branch of the tree.
c. places the organisms that share a common ancestor on the same branch of the tree.
d. shows the order in which populations split and evolved into new species.
e. All of the above
23. The branching patterns of the evolutionary Tree of Life are based on a rich array of evidence from
b. DNA sequencing.
c. metabolic processes.
d. Both a and c
e. All of the above
24. Heterotrophs cannot obtain their energy directly from
25. Members of the kingdom Animalia obtain their energy directly from
c. other organisms.
26. Heterotrophs obtain their energy from
c. other organisms.
27. Which of the following is not a major step in the hypothetico-deductive method?
a. Controlling an environment
28. After observing that fish live in clean water but not in polluted water, you make the statement, “polluted water kills fish.” Your statement is an example of
d. a hypothesis.
29. The key purpose of any single experiment is to
e. test predictions that are based on hypotheses.
30. Which of the following is not a feature of scientific hypotheses?
a. They are unable to be falsified.
31. Which of the following statements about Pieter Johnson’s experiments on frog limb deformities is correct?
a. In a set of comparative experiments, he had to reject his hypothesis that environmental contaminants were causing limb deformities in the frogs.
32. Which of the following statements about the scientific method is correct?
a. Deductive logic is used to make predictions from a hypothesis.
33. The advantage of controlled experiments is that
a. all variables are held constant except one.
34. Which of the following statements is false?
d. Scientists generally conclude that the differences they measure are true if the statistical tests show that the probability of error is 5 percent or lower.
35. Which of the following questions cannot be answered using the hypothetico-deductive method?
b. Are red roses more beautiful than yellow roses?
1. Most living organisms consist of one or more _______, contain _______ that is used to _______ themselves, are genetically related, have _______, and can regulate their _______.
2. _______ are structural, physiological, or behavioral traits that enhance an organism’s chance of survival and reproduction in its environment.
3. Currently, scientists agree with the estimate that life first appeared approximately _______ years ago.
4. Fatlike molecules were the critical ingredient in the enclosure of biological molecules in _______ because these molecules are _______ in water and tend to form membrane-like _______.
5. About _______ years ago, prokaryotes acquired the ability to photosynthesize.
6. Some organelles in eukaryotes can be described as _______ within a cell.
7. In contrast to eukaryotic cells, prokaryotes lack _______.
8. The total chemical activity of a living organism is its _______.
9. Single-celled organisms that lack discrete intracellular compartments belong to the two kingdoms called _______ and _______.
10. There are three domains used to categorize life forms that have evolved separately for about a billion years: _______, _______, and _______.
11. As many as _______ species inhabit Earth.
12. A Pacific tree frog has the scientific nomenclature of Hyla regilla. This particular tree frog belongs to the genus _______.
13. An _______ shows the evolutionary relationships among species.
14. Multicellular organisms that are photosynthetic belong to the kingdom called _______.
15. Fungi and animals are both _______.
16. Nonphotosynthetic multicellular organisms that ingest their food and absorb the products of digestion belong to the kingdom called _______.
17. All scientific study begins with making observations, asking questions, and forming testable _______.
18. The _______ hypothesis states that no difference exists due to the variable under investigation.
1. Probes indicating that there is a dry lake bed and trapped water beneath the poles on Mars are of major significance because they suggest that
2. The part of the atom that determines how the atom behaves chemically is the
3. Which component of an atom does not significantly add to the mass of an atom?
4. What is the difference between an atom and an element?
a. An atom is made of protons, electrons, and sometimes neutrons; an element is a substance composed of only one kind of atom.
5. The number of protons in an atom equals the number of
6. Which of the following statements about atoms is true?
c. When protons equal electrons, an atom has a neutral charge.
7. 3115P and 3215P have virtually identical chemical and biological properties because they have the same
e. number of electrons.
8. An atom that is neutrally charged contains
d. the same number of positive particles as negative particles.
9. Phosphorus has an atomic number of 15 and an atomic weight of 30.974. How many neutrons does phosphorus have?
10. The atomic number of an element is the same as the number of _______ in each atom.
11. The number of different elements found in the universe is closest to
12. The best reference source for the atomic number and mass number of elements is
13. Which of the following elements is contained by all living things?
d. Carbone. All of the above
14. Which of the following pairs has similar chemical properties?
d. 12C and 14C
15. The four elements most common in organisms are
c. carbon, oxygen, hydrogen, and nitrogen.
16. Because atoms can have the same number of protons but a different number of neutrons, elements have
17. An element has a weight of 131.3. The reason the number is not a whole number is that
b. atomic weight is the average of the mass numbers of all the element’s isotopes.
18. Why is the atomic weight of hydrogen 1.008 and not exactly its mass number, 1.000?
b. Atomic weight is the average of the mass numbers of a representative sample of the element, including all its isotopes.
19. The mass number of an atom is determined primarily by the _______ it contains.
d. sum of the number of protons and neutrons
20. Hydrogen, deuterium, and tritium all have the same
21. Of the following atomic configurations, the one that has an atomic mass of 14 is the atom with
22. The ability of atoms to combine with other atoms is determined by
b. the number and distribution of electrons.
23. Phosphorus has an atomic number of 15 and an atomic weight of 30.974. From this information it can be determined that this element
a. has isotopes.
24. The atomic mass of an element is the same as the number of _______ in each atom.
d. protons plus neutrons
25. Which of the following elements is the most chemically reactive?
26. When magnesium (Mg) bonds with another element, you would expect that it would
c. lose two electrons to the other element.
27. All of the elements listed below follow the octet rule except
28. Which of the following statements about the difference between ionic bonds and covalent bonds is true?
b. Electron sharing is more equal in the covalent bond.
29. Which of the following is the correct order (in decreasing order) for the relative strengths of chemical bonds?
a. Covalent, ionic, hydrogen, van der Waals forces
30. In a hydrogen molecule, the two atoms are held together by
b. a shared pair of electrons.
31. What determines if a molecule is polar, nonpolar, or ionic?
c. The differences in the electronegativities of the atoms
32. A single covalent chemical bond represents the sharing of how many electrons?
33. All of the following are nonpolar except
34. Two atoms are held together in four covalent bonds because of forces between the
35. Two carbon atoms held together in a double covalent bond share _______ electron(s).
36. Which of the following atoms usually has the greatest number of covalent bonds with other atoms?
37. Oxygen forms _______ bond(s), carbon forms _______, and hydrogen forms _______.
d. two; four; one
38. A covalent bond is the sharing of _______ between atoms, whereas an ironic bond is the _______.
e. electrons; transfer of electrons from one atom to another
39. Chemical bonds formed by electrical attractions are
40. Ionic bonds are
a. attractions between oppositely charged ions.
41. Particles having a net negative charge are called
42. Which of the following molecules is held together primarily by ionic bonds?
43. Hydrogen bonds
c. form between a strong electronegative atom and hydrogen.
44. Cholesterol is composed primarily of carbon and hydrogen atoms. Therefore, one would expect cholesterol to be
a. insoluble in water.
45. A van der Waals interaction is an attraction between
a. the electrons of a nonpolar molecule and the nucleus of a nearby nonpolar molecule.
46. In addition to covalent and ionic bonds, which of the following interactions are important in biological systems?
van der Waals interactions
b. Hydrogen bonds
c. Hydrophobic interactions
d. Both a and b
e. All of the above
47. The hydrogen bond between two water molecules arises because water is
48. Which of the following correctly states an unusual property of water?
e. The hydrogen bonds between water molecules continually form and break.
49. Two characteristics of water make it different from most other compounds: Its solid state is _______ its liquid state and it takes up _______ heat to change to its gaseous state.
a. less dense than; large amounts of
50. Sweating is a useful cooling device for humans because water
a. takes up a great deal of heat in changing from its liquid state to its gaseous state.
51. When exposed to extreme heat, the human body relies on _______ to absorb excess calories of heat and maintain normal body temperature.
52. Which characteristic of water contributes to the relatively constant temperatures of the oceans?
e. It takes a large amount of heat energy to raise the temperature of water.
53. Ice floats because
a. the crystal takes up more space than the liquid.
54. Ice is used in beverages because
e. it absorbs a lot of heat when it melts.
55. If you place a paper towel in a dish of water, the water will move up the towel by capillary action because water
d. can form hydrogen bonds.
56. Surface tension and capillary action occur in water because it
c. has hydrogen bonds.
57. The molecular weight of water is 18.0154. One mole of water weighs exactly _______ grams.
58. When sodium hydroxide (NaOH) is added to water, it ionizes, releasing OH– and Na+ ions. The resulting solution is
59. H2SO4 can ionize to yield two H+ ions and one SO42– ion. H2SO4 is
e. an acid.
60. Which contains more molecules, a mole of hydrogen or a mole of carbon?
c. Both contain the same number of molecules.
61. The difference between an acid and a base is that an acid _______, whereas a base _______.
e. releases H+ ions in solution; accepts H+ ions
62. To determine the number of molecules in a teaspoon of sugar you need to know
e. the weight and molecular weight of the sugar, and Avogadro’s number.
63. How would you make 100 ml of an aqueous solution with a 0.25 M concentration of a compound that has a molecular weight of 200 daltons?
e. Take 5 grams of the compound and add water until the volume equals 100 ml.
64. Of the following compounds containing 1H, 12C, and 16O, the one with the greatest number of molecules in a sample with a mass of 2 grams would be
65. A basic solution contains
a. more OH– ions than H+ ions.
66. A 1.0 M solution of HCl has a pH of
67. The pH 6.0 contains
e. 10–6 moles of hydrogen ions.
68. The more acidic of two solutions has
c. more H+ ions per liter.
69. Solutions that contain buffers tend to resist pH changes because buffers
c. change from nonionic to ionic in response to changes in pH and release or absorb H+.
70. Acid rain is a serious environmental problem. A sample of rainwater collected in the Adirondack Mountains had an H+ concentration of 10–4 mol/L. The pH of this sample was
71. Carbonic acid and sodium bicarbonate act as buffers in the blood. When a small amount of acid is added to this buffer, the H+ ions are used up as they combine with the bicarbonate ions. When this happens, the pH of the blood
c. does not change.
72. The notation [H+] refers to the
d. concentration of H+ ions in moles per liter.
73. Which of the following has the greatest concentration of hydrogen ions?
e. Cola at pH 3
74. The optimum pH for growing strawberries is 6.5, whereas the optimum pH for growing blueberries is 4.5. Therefore, the number of hydrogen ions needed to grow strawberries is _______ times the number needed for blueberries.
1. One dalton is the same as the mass of one _______.
2. Every atom except for _______ has one or more neutrons in its nucleus.
3. Oxygen and carbon are defined as different elements because they have atoms with a different number of _______.
4. The sum of the atomic weights in any given molecule is called its _______.
5. The chemical properties of an element are determined by the number of _______ its atoms contain.
6. _______ occurs when one atom, such as 14C, is transformed into another atom, such as 14N, with an accompanying emission of energy.
7. The tendency of atoms in stable molecules to have eight electrons in their outermost shells is known as the _______.
8. A _______ is two or more atoms linked by chemical bonds.
10. The electronegativity of an atom depends upon the number of _______ and how far the _______ are from the nucleus.
11. Molecules that have an unequal distribution of electric charge are called _______ molecules.
12. Of the different types of chemical bonds, the strongest bond in biological systems is the _______ bond.
13. The attraction between a slight positive charge on a hydrogen atom and the slight negative charge of a nearby electronegative atom is a _______.
14. In the equation, C6H12O6 Æ 6CO2 + 6H2O, C6H12O6 is the _______.
15. The water strider skates along the surface of water due to a property of liquids called _______.
16. The calories needed to raise one gram of a substance 1°C is known as _______.
17. One mole of a substance contains 6.02 ¥ 1023 molecules. This number is known as_______.
18. A chemical reaction that can proceed in either direction is called a _______.
9. The molecular weight of glucose (C6H12O6) is _______.
1. In the 1920s, circumstantial evidence indicated that DNA was the genetic material. Which of the following experiments led to the acceptance of this hypothesis?
a. Griffith’s experiments with Streptococcus pneumoniae
b. Avery, MacLeod, and McCarty’s work with isolating the transforming principle
c. Hershey and Chase’s experiments with viruses and radioisotopes
2. In Griffith’s experiments, when heat-killed S strain pneumococci were injected into a mouse along with live R strain pneumococci,
b. DNA from the heat-killed S was taken up by the live R, converting the latter to S and killing the mouse.
3. Experiments designed to identify the transforming principle were based on
c. selectively destroying the different macromolecules in a cell-free extract.
4. Griffith’s experiment with pneumococcus demonstrated that
c. materials from dead organisms can affect and change living organisms.
5. Griffith was able to distinguish the two strains of pneumococcus by means of
a. the appearance of the colonies in culture.
b. differences in their lethality in mice.
6. In order to show that DNA is the “transforming principle,” Avery, MacLeod, and McCarty showed that DNA could transform nonvirulent strains of pneumococcus. Their hypothesis was strengthened by their demonstration that
b. enzymes that destroy nucleic acids also destroy transforming activity.
7. The Hershey–Chase experiment
d. helped prove that DNA is the genetic molecule.
8. Before the discovery of DNA, the hereditary material was thought to be made of proteins and not nucleic acids because
c. proteins seemed to be much more chemically diverse.
9. The Hershey–Chase experiment persuaded most scientists that
b. DNA is indeed the carrier of hereditary information.
10. During infection of E. coli cells by bacteriophage T2,
d. only nucleic acids enter the cell.
11. Bacteriophage nucleic acids were labeled by carrying out an infection of E. coli cells growing in
c. 32P-labeled phosphate.
12. If Hershey and Chase had found 35S in both the pellet and the supernatant, what would have been their likely conclusion about the nature of DNA replication?
b. No conclusion would have been possible from these results.
13. The Hershey–Chase experiment determined that
d. DNA, not protein, is the hereditary material of viruses.
14. Which of the following molecules functions to transfer information from one generation to the next in eukaryotes?
15. The rules formulated by Erwin Chargaff state that
a. A = T and G = C in any molecule of DNA.
16. Purines include
e. adenine and guanine.
17. Information sources used by Watson and Crick to determine the structure of DNA included
e. X-ray crystallography of double-stranded DNA.
18. If a double-stranded DNA molecule contains 30 percent T, it must contain _______ percent G.
19. The base composition of DNA isolated from a newly discovered virus is found to be 32 percent A, 17 percent C, 32 percent G, and 19 percent T. What would be a reasonable explanation for this observation?
d. The genome of the phage is single-stranded, not double-stranded.
20. The DNA isolated from a newly discovered virus is found to be 32 percent A, 17 percent C, 32 percent G, and 19 percent T. The base composition of the complementary DNA would be _______ percent A, _______ percent C, _______ percent G, and _______ percent T.
b. 19; 32; 17; 32
21. Which feature of the Watson–Crick model of DNA structure explains its ability to function in replication and gene expression?
a. Each strand contains all the information present in the double helix.
22. Chargaff’s rule states that
e. the amount of cytosine equals the amount of guanine.
23. A deoxyribose nucleotide is a
c. deoxyribose plus a nitrogenous base and a phosphate.
25. The structure of the DNA molecule was determined by the experiments of
26. Which of the following molecular models describes the structure of the DNA molecule?
e. Helical, double-stranded, and antiparallel
27. Double-stranded DNA looks a little like a ladder that has been twisted into a helix, or spiral. The side supports of the ladder are
d. alternating sugars and phosphates.
28. The steps of the ladder are
b. pairs of bases.
29. The structure of DNA is characterized by a
b. right-handed double helix and antiparallel strands.
30. The characteristic of DNA that allows it to make an exact copy of itself is its
b. complementary base pairing.
31. The nitrogenous bases (and the two strands of the DNA double helix) are held together by
c. hydrogen bonds.
32. Which of the following statements about the molecular architecture of DNA is true?
a. The two strands run in opposite directions.
b. The molecule’s twist is right-handed.
c. The molecule is a double-stranded helix.
d. It has a uniform diameter.
33. What accounts for the uniform diameter of the DNA molecule?
b. A purine always bonds with a pyrimidine.
34. The strands that make up DNA are antiparallel. This means that
c. the 5’ to 3’ direction of one strand is counter to the 5’ to 3’ direction of the other strand.
35. The antiparallel relationship of the two strands of DNA refers to the
c. alignment of the strands, such that one strand starts with a 3’ carbon and the other starts with a 5’ carbon.
36. The force of _______ holds DNA together in a double helix.
e. hydrogen bonds
37. Which one of the following is not found in DNA?
38. Although DNA is made up of only four different bases, it can encode the information necessary to specify the workings of an entire organism because DNA
a. molecules are extremely long.
39. The structure of DNA explains which three major properties of genes?
e. They contain information, replicate exactly, and can change to produce a mutation.
40. Mutations are
b. heritable changes in the sequence of DNA bases.
41. The first scientist(s) to suggest a mode of replication for DNA was (were)
d. Watson and Crick.
42. A deoxyribose nucleoside is a
a. deoxyribose plus a nitrogenous base.
43. Kornberg showed that new DNA molecules can be synthesized in a test tube containing deoxyribose
c. nucleoside triphosphates.
44. At the end of DNA replication, two DNA molecules are produced, each one consisting of a parental DNA strand and a new DNA strand. This process is known as
a. semiconservative replication.
45. In the Meselson–Stahl experiment, the conservative model of DNA replication was ruled out by which of the following observations?
a. No completely “heavy” DNA was observed after the first round of replication.
46. During DNA replication
b. the template strands must separate so that both can be copied.
47. If Meselson and Stahl had observed one intermediate, slightly smeared band after growing bacteria for one generation, and then after two generations again had found one slightly smeared band, they would most likely have concluded that DNA replicates
48. In DNA replication, each newly made strand is
b. complementary in sequence to the strand from which it was copied.
49. Semiconservative replication of DNA involves
a. each of the original strands acting as a template for a new strand.
50. In a growing DNA strand, each monomer is added to which carbon of the deoxyribose?
51. During replication, the new DNA strand is synthesized
b. in the 5’ to 3’ direction.
52. DNA replication in eukaryotes differs from replication in bacteria because
c. there are many replication forks in each eukaryotic chromosome and only one in bacterial DNA.
53. In eukaryotic cells, each chromosome has
c. many origins of replication.
54. The energy necessary for making a DNA molecule comes directly from the
c. release of phosphates.
55. Pyrophosphate is a
b. by-product of DNA synthesis.
56. DNA polymerase lengthens a polynucleotide strand by
d. covalently linking new nucleotides to a previously existing strand.
57. Why is RNA incorporated into the DNA molecule during DNA replication?
d. DNA polymerases can only add on to an existing strand.
58. The molecules that function to replicate DNA in the cell are
b. DNA polymerases.
59. Which of the following is the correct order of events for synthesis of the lagging strand?
a. Primase adds RNA primer, DNA polymerase III creates a stretch, DNA polymerase I removes the primer, and ligase seals the gaps.
60. Fragments like those now called Okazaki fragments were expected even before they were discovered because
b. the replication fork moves forward along a double-stranded DNA molecule.
61. In eukaryotes, Okazaki fragments are about _______ base pairs long.
62. The enzyme DNA ligase is required continuously during DNA replication because
b. fragments of the lagging strand must be joined together.
63. In bacteria, the enzyme that removes the RNA primers is called
e. DNA polymerase I
64. The enzyme that restores the phosphodiester linkage between adjacent fragments in the lagging strand during DNA replication is
a. DNA ligase.
65. The enzyme that unwinds the DNA prior to replication is called
66. Fourteen human DNA polymerases have been identified. Which of the following statements about them is true?
e. Only one of the fourteen is involved in DNA replication; the others are involved in primer removal and DNA repair.
67. Why don’t cells last the entire lifetime of an organism?
a. The removal of the RNA primer following DNA replication leads to a shortening of the chromosome and eventual cell death.
68. In the cells of prokaryotes, methylated guanine contributes to
e. correcting of mismatched pairs of bases.
69. The first repair of mistakes during DNA replication is made by
b. DNA polymerase.
70. The error rate of changing an incorrect base with another incorrect base during proofreading is one in _______ bases.
71. The fidelity of DNA replication is astounding. During DNA synthesis, the error rate is on the order of one wrong nucleotide per
72. In PCR, _______ creates single-stranded DNA template molecules.
73. Ideally, PCR _______ increases the amount of DNA during additional cycles.
74. The maximum length of a DNA sequence that can be determined using current technology is approximately _______ base pairs.
1. The material that changed R strain pneumococcus into the virulent S strain was originally referred to as the _______.
2. The nitrogenous bases classified as purines are _______ and _______.
3. Watson and Crick used three-dimensional representations of the possible molecular structure of DNA to determine its actual structure. This process is called _______.
4. The nitrogenous bases classified as pyrimidines are _______ and _______.
5. The X-ray crystallographs of the English chemist _______ were essential for the discovery of the structure of the DNA molecule.
6. The basic units of DNA and RNA molecules are the _______.
7. The purines take up (more/less) _______ space in the center of a DNA molecule than the pyrimidines do.
8. Since the DNA molecule is continuous, nucleotide pair after nucleotide pair, their information must lie in the _______ sequence of the nitrogenous bases.
9. Arthur Kornberg showed that DNA could replicate in the test tube if it contained intact DNA for a template, a mixture of the four precursors (the four nucleoside triphosphates), and _______.
10. The experiments of Meselson and Stahl established the _______ of DNA.
11. Meselson experimental system for studying the mode of replication of DNA, researchers analyze information from a life-form from Mars. After the first round of replication, they see two distinct bands in the This finding is consistent with the principle of _______ replication.
12. The region of DNA where replication begins is called the _______.
13. In bacteria, the enzyme that replicates the lagging strand is _______.
14. In prokaryotes, the enzyme that replicates the leading strand is _______.
15. The fragments of RNA and DNA found on the lagging strand of DNA before RNA removal and ligation are called _______.
16. The repetitive sequences at the end of many chromosomes are called _______.
17. An enzyme that is found in 90 percent of human cancers and may be responsible for the continuous division of cancer cells is _______.
18. An enzyme that catalyzes the addition of any lost telomere sequences is _______.
19. The _______ function of DNA polymerase reduces the number of mistakes by the square of the frequency of the error rate.
20. An automated process that makes multiple copies of short regions of DNA in a test tube is called _______.
21. In a sequencing reaction, the shortest sequences are those that end closer to the _______ end than to the _______ end of the synthesized molecule.
22. The technique that sorts DNA fragments by length and detects differences in DNA fragment length is called _______.
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