Deck 4: Nucleic Acids and the Origin of Life

Question 1

Which is an example of a nucleotide?

A)
B)
C)
D)
E)

Answer 1

C

Question 2

Ribose and deoxyribose are both found in nucleic acids.The difference between ribose and deoxyribose is that

A) deoxyribose has one more oxygen atom than ribose.
B) ribose is a pentose sugar, whereas deoxyribose is a hexose sugar.
C) deoxyribose forms a six-membered ring, whereas ribose forms a five-membered ring.
D) ribose has a higher molecular weight than deoxyribose because of its extra hydroxyl group.
E) deoxyribose bonds to purines, whereas ribose bonds to pyrimidines.

Answer 2

D

Question 3

All of the following bases are found in DNA except

A) thymine.
B) adenine.
C) uracil.
D) guanine.
E) cytosine.

Answer 3

C

Question 4

In DNA, bonding of A with T and bonding of C with G are examples of

A) complementary base pairing.
B) a dehydration reaction.
C) a reduction reaction.
D) a hydrophobic interaction.
E) a purine-purine interaction.

Question 5

Single-stranded RNA can fold back on itself, creating three-dimensional structures such as tRNA.The folds are stabilized by _______ bonds.

A) hydrogen
B) ionic
C) phosphodiester
D) peptide
E) glycosidic

Question 6

DNA utilizes the bases guanine, cytosine, thymine, and adenine.In RNA, _______ is replaced by _______.

A) adenine; arginine
B) thymine; uracil
C) cytosine; uracil
D) cytosine; arginine
E) cytosine; thymine

Question 7

According to the principle of complementary base pairing, purines always pair with

A) deoxyribose sugars.
B) uracil.
C) pyrimidines.
D) adenine.
E) guanine.

Question 8

What type of bond connects two complementary nucleotides?

A) Hydrogen
B) Ionic
C) Peptide
D) Phosphodiester
E) Covalent

Question 9

Complementary base pairing occurs due to

A) covalent bonds between bases.
B) pairing of a purine with a pyrimidine.
C) hydrophobic interactions.
D) hydrogen bonds between sugar residues.
E) pairing of two purines or two pyrimidines.

Question 10

DNA differs from RNA in that

A) RNA contains thymine whereas DNA contains uracil.
B) base pairing is only possible between strands of DNA.
C) only DNA is present in the cell nucleus.
D) RNA contains pentose sugar residues whereas DNA contains hexose sugar residues.
E) only DNA has an equal number of purines and pyrimidines.

Question 11

The "backbone" of a nucleic acid molecule is made of

A) nitrogenous bases.
B) alternating sugar and phosphate groups.
C) purines.
D) pyrimidines.
E) nucleosides.

Question 12

A nucleotide contains a pentose sugar, a phosphate group, and a(n)

A) lipid.
B) acid.
C) nitrogen-containing base.
D) amino acid.
E) glycerol.

Question 13

Suppose you obtain four different samples of nucleic acids.You analyze the nitrogenous base composition of each one and get the results in the table below (the numbers indicate percentage of each nitrogenous base in the samples). Which of these nucleic acids is/are single-stranded RNA?

A) A
B) B
C) C
D) D
E) Both C and D

Question 14

Nucleotides in RNA are connected to one another in the polynucleotide chain by _______ bonds between _______.

A) hydrogen; a sugar and a phosphate group
B) covalent; two phosphates
C) covalent; two sugars
D) hydrogen; two phosphate groups
E) covalent; a sugar and a phosphate group

Question 15

Which of the following statements about DNA and RNA is true?

A) DNA has uracil, whereas RNA has thymine.
B) DNA usually has one polynucleotide strand, whereas RNA usually has two strands.
C) DNA contains pentose sugars, whereas RNA contains hexose sugars.
D) DNA is a polymer, whereas RNA is a monomer.
E) In DNA, A pairs with T, whereas in RNA, A pairs with U.

Question 16

What is the nucleotide sequence of the complementary strand of the following DNA molecule: AATGCGA?

A) TTACGCT
B) AATGCGA
C) GGCATAG
D) CCGTTAT
E) AGCGTAA

Question 17

The bases of nucleic acids are purines or pyrimidines.Which statement contrasting purines and pyrimidines is true?

A) Purines include the bases cytosine and thymine, whereas pyrimidines include the bases adenine and guanine.
B) Pyrimidines are found in RNA, whereas purines are found in DNA.
C) Purines are double-ring structures, whereas pyrimidines are single-ring structures.
D) Purines have only single bonds in their structure, whereas pyrimidines have both single and double bonds in their structure.
E) Purines consist of hydrogen, carbon, oxygen, and nitrogen, whereas pyrimidines have phosphorus, hydrogen, carbon, oxygen, and nitrogen.

Question 18

The four nitrogenous bases of RNA are abbreviated as

A) A, G, C, and T.
B) A, G, T, and N.
C) A, G, C, and U.
D) A, G, U, and T.
E) G, C, U, and N.

Question 19

Which factor contributes to the strength of the intermolecular interaction between two DNA strands in a double helix?

A) Hydrogen bonds between purines and pyrimidines
B) Phosphodiester bonds between the nitrogenous bases
C) Strong hydrogen bonds between the sugar and phosphate groups
D) Its double-helix shape
E) The direct bonding of the base to the phosphate molecule

Question 20

What is attached to the 5ʹ carbon of deoxyribose in DNA?

A) Adenine
B) Phosphate
C) Guanine
D) Thymine
E) Uracil

Question 21

In the DNA double helix, the bases in one strand are complementary to the bases in the other strand.Therefore,

A) a purine in one strand will attach to any pyrimidine in the other strand.
B) the bases in one strand will be the same as those of the other strand.
C) a pyrimidine in one strand will attach to any pyrimidine in the other strand.
D) a purine in one strand will attach to a different purine in the other strand.
E) a purine in one strand will attach to only one type of pyrimidine in the other strand.

Question 22

Which statement concerning genetic information in most cells is true?

A) The entire DNA molecule is copied to RNA during DNA replication.
B) A single DNA nucleotide codes for a single amino acid.
C) The flow of information in a cell is from DNA to RNA to protein.
D) The flow of information in a cell is from protein to RNA to DNA.
E) The flow of information in a cell is from DNA to protein to RNA.

Question 23

Which statement about DNA base sequences is true?

A) The more distant the evolutionary relationship between two species, the greater the similarity in their DNA base sequences.
B) Comparisons of DNA base sequences cannot be used to make inferences about the evolutionary relatedness of two species.
C) The chimpanzee and human genomes share 18 percent of their DNA base sequences.
D) Evolutionary relationships between species are more accurately determined by DNA base sequence analysis than by comparisons of physical or behavioral characteristics.
E) The human genome contains only part of the biological information present in the human body.

Question 24

The copying of a DNA sequence to make an RNA sequence is called

A) catalysis.
B) replication.
C) translation.
D) transcription.
E) expression.

Question 25

Refer to the figure below showing two strands of DNA. Which statement about uracil can you infer to be true?

A) It has a double ring and forms two hydrogen bonds.
B) It has a single ring and forms two hydrogen bonds.
C) It has a double ring and forms three hydrogen bonds.
D) It has a single ring and forms three hydrogen bonds.
E) It has a single ring and forms one hydrogen bond.

Question 26

Which statement about DNA or RNA is true?

A) DNA is completely replicated but only partially transcribed.
B) DNA is partially replicated but completely transcribed.
C) RNA is completely replicated but only partially translated.
D) DNA is completely replicated and completely translated.
E) DNA is partially replicated but completely translated.

Question 27

If there is an exposed purine during DNA replication,

A) any purine will be joined to it.
B) a specific purine will be joined to the exposed purine, depending on which purine is exposed.
C) a specific pyrimidine will be joined to the exposed purine, depending on which purine it is.
D) any pyrimidine will be joined to it.
E) a phosphate group will be joined to the exposed purine.

Question 28

If pyrimidines could bind to other pyrimidines, and purines could bind to other purines, what would be the effect on the DNA double helix?

A) The width of the double helix would vary rather than being fixed.
B) The phosphodiester bonds would be unable to form.
C) There would be a reduced requirement for phosphates in nucleotides.
D) The DNA backbone would be made of nucleosides.
E) The sugar would have to be ribose instead of deoxyribose.

Question 29

Nucleic acids and proteins are both polymers made of a set of monomers.Complete the following analogy: _______ are to nucleotides as side chains are to amino acids.

A) ribose/deoxyribose sugars
B) phosphate ions
C) nitrogenous bases
D) nucleosides
E) hydroxyl groups

Question 30

Consider the following double-stranded DNA region: 5ʹ-TGCCAT-3ʹ
3ʹ-ACGGTA-5ʹ
If the lower strand is transcribed, which strand will result?

A) TGCCAT
B) TCGGTA
C) UGCCAU
D) UGCCUA
E) TCGGUT

Question 31

With a few exceptions, each human cell contains DNA in its nucleus.Which statement about any cell containing DNA is true?

A) The entire genome is expressed in each cell.
B) The cell discards some of its DNA so that only genes with a function in that cell are retained.
C) Cells synthesize RNA transcripts from its DNA before discarding the DNA.
D) Different genes may be expressed at different times in a single cell.
E) Cell functioning differs depending on the DNA present in the cell.

Question 32

Complementary base pairing between nucleotides makes which process possible?

A) Hydrolysis of DNA
B) Formation of phosphodiester bonds in polynucleotides
C) DNA replication prior to cell division
D) Movement of mRNA from nucleus to cytoplasm
E) Biosynthesis of nucleotide building blocks by a cell

Question 33

What is the sequence of the complementary strand of RNA made from this template sequence? 5ʹ-AGC TTC GCT GAA GCT CGG-3ʹ
(Note: The spaces between the nucleotides have been inserted in order to make the sequence easier to read.)

A) 5ʹ-UCG AAG CGA CUU CGA GCC-5ʹ
B) 3ʹ-UCG AAG CGA CUU CGA GCC-5ʹ
C) 3ʹ-TCG AAG CGA CTT CGA GCC-5ʹ
D) 5ʹ-GGC TCG AAG TCG CTT CGA-5ʹ
E) 5ʹ-TCG AAG CGA CTT CGA GCC-3ʹ

Question 34

Refer to the figure below showing two strands of DNA. How many hydrogen bonds would there be in a DNA sequence of ten base pairs in which there are five A-T and five C-G pairs?

A) 5
B) 10
C) 15
D) 25
E) 18

Question 35

Complementary base pairing between strands of nucleic acids is limited to particular pairings because of

A) the relative sizes and shapes of purines and pyrimidines.
B) the alternating sugar-phosphate groups.
C) evolutionary relationships.
D) the differences found between RNA and DNA.
E) the diversity found in DNA molecules.

Question 36

The end product of transcription is _______, and the end product of translation is _______.

A) proteins; DNA
B) proteins; RNA
C) RNA; DNA
D) DNA; RNA
E) RNA; proteins

Question 37

Refer to the table below showing the percent overlap in genomic sequences between species pairs. Which two species are most closely evolutionarily related, and which two are most distantly related?

A) Species A and D are most closely related, while species B and C are most distantly related.
B) Species B and C are most closely related, while species A and D are most distantly related.
C) Species A and B are most closely related, while species B and D are most distantly related.
D) Species C and D are most closely related, while species A and C are most distantly related.
E) Species A and B are most closely related, while species B and C are most distantly related.

Question 38

The double-stranded structure of DNA results from

A) hydrophobic interactions.
B) purines bonding with purines and pyrimidines bonding with pyrimidines.
C) the phosphodiester bonds between deoxyribose and phosphate.
D) hydrogen bonding within and between polynucleotide strands.
E) ionic bonding between base pairs.

Question 39

The diversity in DNA molecules is due to

A) physical shape differences.
B) differences in size between A-T and G-C base pairs.
C) base sequence differences.
D) hydrogen bonding differences.
E) the ability of each base to pair with any of the other three bases.

Question 40

DNA carries genetic information in its

A) helical form.
B) sequence of bases.
C) tertiary sequence.
D) sequence of amino acids.
E) phosphate groups.

Question 41

Which is a plausible explanation for the presence of carbon dioxide in Earth's early atmosphere?

A) Volcanic eruptions could have released carbon dioxide into the atmosphere.
B) Cyanobacteria were present on Earth 3.5 billion years ago.
C) Retroviruses could have catalyzed the formation of carbon dioxide.
D) Geysers may have produced Earth's early environment.
E) Chemical reactions with water would have resulted in the formation of carbon dioxide.

Question 42

In 1668, Francesco Redi conducted experiments to investigate the concept of spontaneous generation.He began by putting pieces of meat into identical jars.Some jars were left open to the air, some were sealed, and some were covered with gauze that kept out flies while allowing the meat to be exposed to the air.Redi then observed whether or not fly maggots appeared in the meat.What hypothesis was Redi testing?

A) Spontaneous generation is more likely to occur during the hot days of summer.
B) Maggots do not arise spontaneously, but from eggs laid by adult flies.
C) The type of meat affects whether spontaneous generation occurs.
D) Spontaneous generation can occur only if air is present.
E) Flies will develop from rotting meat if the meat is exposed to air.

Question 43

Refer to the figure below illustrating Louis Pasteur's experiment on spontaneous generation. Why was the neck broken on one flask but not the other?

A) To ensure that conditions were the same in both experimental setups
B) To prevent contaminants from getting in through the neck
C) To allow dust to enter into the broken flask but not the unbroken one
D) To show that the neck of the flask does not introduce an added variable to the experiment
E) To allow air to enter the control flask

Question 44

The most likely source of early Earth's atmospheric oxygen was

A) volcanic eruptions.
B) lightning striking water vapor.
C) the spontaneous breakdown of fatty acids.
D) photosynthesis by ancient cyanobacteria (blue-green algae).
E) the decay of fossil organisms.

Question 45

Changes to the original Miller‒Urey hot chemistry experiment included adding other gases like carbon dioxide (CO₂), nitrogen (N₂), hydrogen sulfide (H₂S), and sulfur dioxide (SO₂) in the test apparatus, which resulted in the production of more small molecules of life than the original experiment had produced. Which products were shown to be significant for the evolution of the cellular membrane?

A) All five bases that are present in nucleic acids (i.e., A, T, C, G, and U)
B) All of the 20 standard amino acids
C) Many 3- to 6-carbon sugars
D) Certain fatty acids
E) Small carboxylic acids

Question 46

Miller and Urey's 1954 hot chemistry experiment was based on the assumption that Earth's early atmosphere contained water (H₂O) vapor, methane, hydrogen, and ammonia.Subsequent research showed that volcanoes released carbon dioxide (CO₂), hydrogen sulfide (H₂S), and sulfur dioxide (SO₂) around 4 billion years ago.This discovery suggests that

A) early small molecules of life may have been produced in volcanoes.
B) Earth's early environment included these gases as well.
C) these gases were toxic to early life forms.
D) volcanoes may have been responsible for the oxygen production once attributed to cyanobacteria.
E) prebiotic synthesis could not have occurred in ice, since volcanoes would have melted the ice.

Question 47

A prerequisite for life as we know it on Earth or any other planet is

A) sunlight.
B) water.
C) amino acids.
D) nitrogen.
E) carbon dioxide.

Question 48

Refer to the figure below illustrating Louis Pasteur's experiment on spontaneous generation. The experiment supports which hypothesis?

A) Amino acids are the building blocks of life.
B) Some forms of life can arise by spontaneous generation.
C) Oxygen is needed for life.
D) Life comes from decaying matter.
E) Life comes from preexisting life.

Question 49

Miller and Urey's 1954 hot chemistry experiment was based on the assumption that Earth's early atmosphere contained water (H₂O) vapor, methane, hydrogen, and ammonia.Subsequent research showed that volcanoes released carbon dioxide (CO₂), hydrogen sulfide (H₂S), and sulfur dioxide (SO₂) around 4 billion years ago.In response to this evidence, scientists concluded that

A) no synthesis of prebiotic molecules was possible on early Earth.
B) the experiment needed to be repeated with the inclusion of CO₂, SO₂, and H₂O.
C) the experiment needed to be repeated with the inclusion of CO₂, SO₂, and H₂S.
D) the experiment needed to be repeated with the inclusion of CO₂, SO₂, and H₂S, and the exclusion of the original gases.
E) the experiment needed to be repeated in the vicinity of an active volcano and with the inclusion of CO₂, SO₂, and H₂S.

Question 50

The French scientist Louis Pasteur showed that, under Earth's present conditions,

A) microorganisms can arise only from other microorganisms.
B) an environment with life will eventually become lifeless.
C) flies arise spontaneously from rotting meat.
D) air is necessary for microorganisms to grow.
E) boiling destroys microorganisms.

Question 51

Changes to the original Miller‒Urey hot chemistry experiment included adding other gases like carbon dioxide (CO₂), nitrogen (N₂), hydrogen sulfide (H₂S), and sulfur dioxide (SO₂) in the test apparatus, which resulted in the production of more small molecules of life than the original experiment had produced.Which products were shown to be significant for the synthesis of proteins?

A) All five bases that are present in nucleic acids (i.e., A, T, C, G, and U)
B) All of the 20 standard amino acids
C) Many 3- to 6-carbon sugars
D) Certain fatty acids
E) Small carboxylic acids

Question 52

Examination of meteorites suggests that

A) prebiotic synthesis of small molecules of life is not limited to Earth.
B) simple life forms can live on meteorites.
C) comets brought Earth most of its water.
D) meteorites brought living cells to Earth.
E) meteorites are responsible for Earth's magnetic field.

Question 53

Which gas was a component of Earth's early atmosphere?

A) Argon
B) Neon
C) Water vapor
D) Oxygen
E) Freon

Question 54

Refer to the figure below diagramming a protein composed of two R subunits and two C subunits.The R subunits are identical and the C subunits are identical, but R and C differ from each other. The figure depicts a nucleotide performing a function.How can this function be described?

A) Information storage
B) Information transfer
C) Energy metabolism
D) Biological activity regulation
E) Electron transfer

Question 55

Why did the Miller‒Urey hot chemistry experiment exclude oxygen in its investigation of the chemical origin of life on Earth?

A) Oxygen is not necessary for life.
B) The scientists assumed the reactions would produce oxygen from water vapor.
C) The scientists assumed that photosynthetic organisms would develop in the apparatus.
D) There is no evidence that oxygen existed in Earth's earliest environments.
E) The scientists wanted to avoid contamination of the apparatus by oxygen-consuming bacteria.

Question 56

In Stanley Miller's long-term cold chemistry experiment concerning prebiotic synthesis, test tubes containing ammonia gas, water vapor, and cyanide (HCN) were cooled to -78°C.When they were opened after 27 years, they contained amino acids and nucleotide bases.This result was interpreted to mean that

A) ice crystals served as templates for molecule formation.
B) the evolution of life would never have occurred on icy planets, because it happens too slowly.
C) ice on moons of Jupiter and Saturn may be environments for prebiotic synthesis.
D) cold temperatures are necessary for small molecule synthesis on other planets.
E) life could only have arisen under extremely cold conditions.

Question 57

The idea of spontaneous generation was disproved through experiments by

A) Stanley Miller.
B) Harold Urey.
C) Francesco Redi and Louis Pasteur.
D) Allan Hills.
E) Johannes van der Waals.

Question 58

After the discovery that volcanoes released carbon dioxide (CO₂), hydrogen sulfide (H₂S), and sulfur dioxide (SO₂) into the atmosphere 4 billion years ago, scientists conducted the Miller‒Urey experiment with the inclusion of these gases.How did the results differ from the original results?

A) No small or large prebiotic molecules were produced.
B) DNA was produced.
C) All 20 amino acids used in protein synthesis were produced.
D) Living cells were produced.
E) Nonliving protocells were produced.

Question 59

The Miller-Urey experiment showed that in an environment with conditions similar to those of Earth,

A) inorganic molecules could react to form organic molecules.
B) RNA could self-replicate.
C) organic molecules could form primitive cells.
D) an oxygen atmosphere could develop.
E) DNA could be synthesized.

Question 60

Which line of evidence supports the hypothesis that the prebiotic synthesis of molecules could occur in water inclusions within ice on celestial bodies such as Europa, a moon of Jupiter?

A) The internal structure of 3.5-billion-year-old fossilized spheres in Australian rocks
B) The synthesis of prebiotic molecules in a heated solution of gases treated with electrical sparks
C) The presence of frozen mammoths in frozen soil in the Yukon
D) The synthesis of prebiotic molecules in test tubes containing ammonia gas, water vapor, and cyanide (HCN) cooled to -78°C
E) The capacity of RNA to act as a catalyst

Question 61

Refer to the figure below illustrating the "RNA world" hypothesis. Which statement about this hypothetical evolutionary model is true?

A) It supports the hypothesis that proteins appeared on Earth before nucleic acids.
B) It would be impossible in reality, since RNA is synthesized from DNA.
C) It would require prebiotic synthesis of fatty acids.
D) It is consistent with the activity of modern retroviruses that synthesize DNA.
E) It is inconsistent with the hypothesis that nucleic acids were the first catalysts.

Question 62

Suppose that scientists succeed in creating experimental conditions that generate living cells from nonliving matter.Which statement best expresses how this achievement will affect thinking about the history of life on Earth?

A) The results will prove that life arose on Earth in a similar way, because it is so difficult to find just the right conditions to recreate the process in a lab.
B) The results will demonstrate that life could have arisen on Earth in a similar way, because we may never know what actual conditions were present on primitive Earth.
C) The results will suggest that life probably arose on Earth in a similar way, because scientists finally succeeded in reproducing the process in a lab.
D) The results will indicate that life could not have arisen on Earth in a similar way, because experiments in labs can never recreate exact conditions in the real world.
E) The results will indicate that life could not have arisen on Earth in a similar way, because there are too many variables and unknowns that make it impossible to test them all.

Question 63

Refer to the figure below showing the Miller‒Urey experiment. Research conducted later than the Miller‒Urey experiment showed that volcanic activity 4 billion years ago injected other gases, such as SO₂, into Earth's early environment.This information led to the conclusion that

A) the original Miller-Urey experiment did not produce meaningful data.
B) a modified experiment should be performed in which other gases would be added to the initial heated solution.
C) the experiment required a longer running time to see whether the other gases would be produced.
D) the beaker of condensed liquid and compounds should be heated in the presence of the additional gases.
E) the Miller‒Urey experiment did not require modification, since cellular life existed earlier than 4 billion years ago.

Question 64

Refer to the figure below showing a simplified time line of the origin of life. Which event could have occurred before the evolution of RNA?

A) Formation of DNA
B) Evolution of cells
C) Prebiotic synthesis of amino acids
D) Development of ribozymes
E) Rise of protocells

Question 65

Which was absent in the products analyzed at the conclusion of the Miller-Urey experiments?

A) Most of the amino acids used in protein synthesis
B) Small carbon sugars
C) Adenine and thymine
D) Nucleotides
E) Uracil

Question 66

RNA molecules that act as catalysts are called

A) ribozymes.
B) glycosidic linkages.
C) chaperonins.
D) disulfide bridges.
E) triglycerides.

Question 67

Retroviruses, such as HIV, have an enzyme that allows them to catalyze DNA synthesis from an RNA template.This evidence supports the hypothesis that

A) RNA itself cannot be a catalyst.
B) early life consisted of an "RNA world."
C) RNA probably came from an extraterrestrial source.
D) chemical evolution led to polymerization.
E) DNA polymers form from RNA monomers.

Question 68

Refer to the figure below showing the Miller‒Urey experiment. The experiment, which was performed in the 1950s,

A) showed that Earth's early environment had an atmosphere of N₂, NH₃, CH₄, H₂O, and H₂.
B) showed that Earth's early atmosphere consisted of a combination of gases that is different from the one that exists today.
C) proved that carbon dioxide was present in Earth's early atmosphere.
D) demonstrated prebiotic synthesis of small molecules of life.
E) led to no meaningful conclusions, because there was no lightning in Earth's early environment.

Question 69

Which was a limitation of the Miller-Urey experiments in the 1950s?

A) The experiments synthesized both d- and l-isomers of amino acids, but the amino acids in living things are always l-isomers.
B) The experimenters made assumptions about Earth's early atmosphere that were later found to be inaccurate.
C) DNA is not self-catalytic.
D) In living organisms today, peptide linkages are catalyzed by ribozymes.
E) The hot temperatures of the experiments denatured some of the proteins that were synthesized.

Question 70

Which of these substances, present in the prebiotic environment on Earth, could have been critical in making the chemical synthesis of biologically important polymers more favorable?

A) Water
B) Sodium ions
C) Methane
D) Nickel ions
E) Hydrogen

Question 71

Which is evidence that supports the hypothesis that DNA could have evolved from RNA?

A) The discovery that retroviruses have an enzyme that catalyzes DNA synthesis from RNA
B) Evidence of the early emergence on Earth of chemical reactions that resulted in monomers
C) Evidence of the nearly spontaneous formation of lipid micelles on Earth
D) Evidence of the prebiotic chemical generation of cell-like compartments
E) The chemical traces of life found on meteorites

Question 72

Which statement is supported by the discovery that RNA can function as a catalyst?

A) Proteins were the first catalysts.
B) An "RNA world" of early life preceded the existence of DNA.
C) Prebiotic synthesis of the four bases of RNA is not necessary for life.
D) The prebiotic origin of small molecules was in ice on cold moons.
E) The prebiotic origin of small molecules occurred around hydrothermal vents.

Question 73

The "RNA world" hypothesis is supported by evidence that

A) RNA molecules spontaneously form spheres in water.
B) RNA can act as both genetic material and a catalyst.
C) amino acids can form RNA in particular chemical environments.
D) RNA can act as genetic material but not as a catalyst.
E) RNA monomers can form proteins.

Question 74

Hot water containing iron and nickel emerges from below Earth's crust at deep ocean hydrothermal vents where there is no oxygen.These metals catalyze the polymerization of amino acids in the absence of oxygen.This evidence supports the hypothesis of

A) the prebiotic synthesis of large molecules in Earth's early environment.
B) photosynthesis by cyanobacteria 3.5 billion years ago.
C) the prebiotic synthesis of small molecules in the ice of Europa, a moon of Jupiter.
D) the evolution of whales.
E) an extraterrestrial origin of life.

Question 75

Chemical reaction rates vary depending on the concentrations of reactants.In which primitive Earth environment would conditions have shifted reactant concentrations to favor increased polymerization of monomers?

A) Rocky outcroppings with full sun exposure
B) Deep, wide freshwater lakes
C) Hot, sandy beaches
D) Shallow ponds with clay bottoms
E) Thermal vents deep in a salty ocean

Question 76

Whether the process is abiotic or occurs in an organism, the synthesis of macromolecules

A) occurs with an increase of entropy.
B) is spontaneous.
C) requires energy.
D) results in a more random system.
E) gives off heat.

Question 77

Which may have facilitated the polymerization of the large molecules of life on primitive Earth?

A) Ice crystals
B) Evaporation in hot pools at the edges of oceans
C) Ribozymes
D) Early proteins
E) Lightning strikes in an anaerobic environment of methane, ammonia, hydrogen, and water vapor.

Question 78

What evidence supports the possibility that life may have come from outside of Earth?

A) Amino acids in a meteorite were found to be a mixture of l- and d-isomers.
B) DNA molecules have been found in meteorites.
C) Other bodies in the solar system have, or once had, oxygen.
D) Other bodies in the solar system have, or once had, long-chain polypeptide molecules.
E) Other bodies in the solar system have gaseous atmospheres.

Question 79

In 1969, scientists shaved off pieces of the Murchison meteorite and found both D- and L-isomers of ten amino acids.Only L-isomers of amino acids are made by living organisms on Earth.This indicates that

A) Earth's amino acids could not have had an extraterrestrial origin.
B) the meteorite's amino acids as a whole could not have resulted from contamination by Earth organisms.
C) basic chemical building blocks of life have only formed on Earth.
D) life must have originated somewhere other than Earth.
E) life arose in many places besides Earth.

Question 80

The Miller-Urey experiments demonstrated that

A) under specific conditions, the basic building blocks of life can form.
B) life on Earth came from other bodies in the solar system.
C) CO₂, N₂, H₂S, and SO₂ were probably present in Earth's early atmosphere.
D) volcanic eruptions may have released CO₂, N₂, H₂S, and SO₂ into Earth's early atmosphere.
E) ice is present in meteorites and on Mars.