Question 1

Refer to the figure below, showing how fatty acids self-assemble to form a bilayer membrane in water.  The arrow indicates the polar head of a(n) fatty acid, which is _______, a term meaning water-loving.This portion of the fatty acid interacts with water molecules.

Accepted Answer

The answer of Refer to the figure below, showing how...

Question 2

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

Accepted Answer

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

Question 3

Information flows from _______ only during cell reproduction.

Accepted Answer

A)  DNA to RNA 
B)  RNA to amino acid sequences 
C)  existing DNA to newly formed DNA 
D)  proteins to existing DNA 
E)  proteins to RNA

Question 4

J.William Schopf discovered a fossil cyanobacterium in Australian rocks that are 3.5 billion years old.The specific ratio of carbon isotopes (13C:12C) in the fossil indicated that the organism

Accepted Answer

A)  produced atmospheric oxygen through photosynthesis. 
B)  produced atmospheric carbon dioxide through photosynthesis. 
C)  used atmospheric carbon dioxide in photosynthesis. 
D)  consumed carbohydrates for energy. 
E)  had an extraterrestrial origin.

Question 5

Fatty acids have hydrophilic heads and hydrophobic tails.This allows them to

Accepted Answer

A)  self-organize into a single layer surrounding a sphere of water. 
B)  form a double-layered membrane with heads facing out and a layer of water between the tails. 
C)  act as catalysts for chemical reactions. 
D)  act as information carriers for protocells. 
E)  self-organize into a double layer surrounding a sphere of water.

Question 6

Which statement concerning chemical reactions and catalysts is true?

Accepted Answer

A)  In living systems, most chemical conversions do not involve catalysts. 
B)  Spontaneous chemical changes occur rapidly in aqueous solutions. 
C)  Water functions as a catalyst in many biochemical conversions. 
D)  Lightning was a catalyst for polymerization of large molecules on early Earth. 
E)  Catalysts are necessary for life because they speed up biochemical reactions that would otherwise take too long to occur.

Question 7

Unlike pyrimidines, purines have a _______-ring structure.

Accepted Answer

The answer of Unlike pyrimidines, purines have a _______-ring structure....

Question 8

One of the first steps leading to a cell that could reproduce may have been the formation of protocells.What characteristics may have allowed protocells to be the precursors to the living cell?

Accepted Answer

The answer of One of the first steps leading to...

Question 9

J.William Schopf found fossils in ancient Australian rocks with an internal structure unlikely to occur through abiotic processes.Additional evidence that these were fossil cyanobacteria includes

Accepted Answer

A)  a carbon isotope ratio (13C:12
C)  consistent with translation of DNA. 
B)  a carbon isotope ratio (13C:12
C)  consistent with photosynthetic activity. 
C)  fossilized DNA. 
D)  fossilized RNA. 
E)  micrometeorites from Mars with amino acids.

Question 10

Which statement concerning genetic information in most cells is true?

Accepted Answer

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 11

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

Accepted Answer

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

Question 12

Nucleotides are composed of

Accepted Answer

A)  one or more amino acids. 
B)  nucleic acids. 
C)  one or more phosphates, a sugar, and a base. 
D)  a base and at least one phosphate. 
E)  fatty acids and a base.

Question 13

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

Accepted Answer

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 14

Which statement about the addition of new nucleotides onto a nucleic acid is true?

Accepted Answer

A)  The phosphate on the new nucleotide joins to the nitrogenous base on the existing chain. 
B)  The phosphate on the new nucleotide and the pentose on the existing chain undergo a condensation reaction. 
C)  The phosphate on the new nucleotide joins to the 3′ carbon of the sugar on the existing chain. 
D)  The nucleotides are joined by a disulfide linkage. 
E)  Nucleic acids grow in the 3′-to-5′ direction.

Question 15

The cold chemistry experiment of Miller showed prebiotic synthesis in test tubes containing ammonia gas, water vapor, and cyanide (HCN) cooled to -78oC.This is the temperature of the ice that covers Europa, one of Jupiter's moons.This result is most consistent with which statement?

Accepted Answer

A)  Earth was at a temperature of -78oC 3.5 billion years ago. 
B)  Life did not form on Earth until the formation of widespread glaciers. 
C)  There is a possible extraterrestrial origin of life on Earth. 
D)  Basic molecules of life cannot originate on a cold moon with water. 
E)  Life on Earth originated in ice-covered environments.

Question 16

What type of bond connects two complementary nucleotides?

Accepted Answer

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

Question 17

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

Accepted Answer

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 18

The complete set of DNA in a living organism is called its _______.

Accepted Answer

The answer of The complete set of DNA in a...

Question 19

What is the significance of modeling experiments performed by Miller and Urey, and what are the limitations of such experiments?

Accepted Answer

The answer of What is the significance of modeling experiments...

Question 20

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

Accepted Answer

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

Exam 4: Nucleic Acids and the Origin of Life

Refer to the figure below, showing how fatty acids self-assemble to form a bilayer membrane in water. The arrow indicates the polar head of a(n) fatty acid, which is _______, a term meaning water-loving.This portion of the fatty acid interacts with water molecules.