Download Reading Quiz 4 (with answers)

Science 3211: Search For Life in the Universe
Reading Quiz 4: Ch 7, 8. Questions on both sides.
Feb 13, 2003
Name: Answers
Chapter 7: The Nature of Life on Earth
Question 1: A monomer is
(a) a single piece of genetic information.
(b) one carbon atom bound with hydrogen, oxygen, or nitrogen.
(c) half of a paramour.
(d) one element of a repetitive chain.
(e) a specific enzyme.
Polymers are long strings of elements called monomers (p. 167). Proteins are polymers of amino acids,
so in that context the amino acids are the monomers.
Question 2: Amino acids are
(a) components of proteins.
(b) a method of encoding genetic information.
(c) components of RNA.
(d) composed of simple sugars.
(e) toxins caused by recessive mutations.
There are 20 amino acids that build up the proteins that make up life (p. 172).
Question 3: DNA
(a) is the scaffolding for building proteins.
(b) stores genetic information in nucleotides.
(c) is composed of proteins.
(d) is the ‘energy storehouse’ for a cell.
(e) is found in meteorites.
DNA molecules store genetic information that tells the next generation of organisms how to carry out
metabolism, to grow, and to reproduce (p. 172) and the monomers that build it up are called nucleotides
(p. 173).
Question 4: RNA
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Search for Life in the Universe: Reading Quiz #4
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(a) is the scaffolding for building proteins.
(b) stores genetic information in nucleotides.
(c) is composed of proteins.
(d) is the ‘energy storehouse’ for a cell.
(e) is found in meteorites.
The protein-synthesizing machinery of the cell does not read the DNA message directly. Instead, the cell
makes “working copies” of the genes it needs at a particular moment. These working copies are not DNA
but the closely related molecule RNA (p. 176).
Chapter 8: The Origin of Life
Question 5: A protocell is
(a) a form of oxygen-emitting blue-green algae.
(b) a protective pocket where organic molecules could form.
(c) an early region of rocky, dry land on the forming planet.
(d) a rock-like ocean growth that occurred on ancient earth and still can be found today.
(e) a ‘spore’ that seeds life.
(p. 199). Protocells are suggested tiny enclosures that allow molecular processes to proceed relatively
unmolested by the environment.
Question 6: The Miller-Urey experiment showed
(a) compounds essential to life can form in the presence of Hydrogen.
(b) compounds essential to life cannot form in the presence of Oxygen.
(c) how polymerization of compounds can occur.
(d) how Nitrogen can be fixed into the soil.
(e) how Oxygen can be produced by early life.
(p. 200–201). With enough hydrogen and some external energy, the experiment produced amino acids,
sugars, the nucleotide bases, and other stuff.
Question 7: Ozone’s crucial role is to
(a) trap radiation inside the Earth’s atmosphere, keeping it warm.
(b) trap reactive Oxygen high in the Earth’s atmosphere, allowing life to form on the surface.
(c) absorb ultraviolet light, preventing photo-dissociation on the surface.
(d) absorb volatile elements, preventing them from leaving the atmosphere.
(e) This is a trick question! Ozone is useless.
Solar ultraviolet radiation would have reached the surface of the primitive Earth before the free hydrogen
had escaped, because no ozone existed... (p. 198).
Question 8: A biomarker
(a) is a Crayola product which allows one to draw on animals.
Search for Life in the Universe: Reading Quiz #4
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(b) is a lipid layer which attracts amino acids.
(c) is any property which distinguishes one branch of life from another.
(d) is a region on a strand of DNA which indicates the beginning of a gene.
(e) is an indication of life.
This is an example of a molecular clue to the existence of life that scientists refer to as a biomarker
(p. 202).