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Mastering biology Exam 1 Questions and Answers
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Mastering biology Exam 1 Questions and Answers
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Mastering biology Exam 1 Questionsand Answers
Who invented the first known microscope? - Answer -Robert Hooke. In 1665, this
Englishman examined cork, magnified 30x. He observed compartments that he named
cells.
One part of the cell theory states that all cells come from _____. - Answer -pre-existing
cells. This is a key part of the cell theory.
In Pasteur's experiment, the purpose of the swan neck on the flask was to: - Answer -
trap cells from the air before they reached the growth medium. This prevented living
cells from the outside from reaching the sterilized growth medium.
Pasteur's results showed that: - Answer -When growth medium is not contaminated by
pre-existing cells, the growth medium remains sterile. This finding disproved the theory
of spontaneous generation.
Natural selection acts only on traits that are _____. - Answer -heritable. Natural
selection can act only on heritable variation. Traits acquired during the lifetime of an
individual organism will not be passed on to offspring. Even if the individual has high
fitness and produces many surviving offspring, non-heritable traits that the individual
has acquired during a lifetime will not be passed on to the offspring.
What is the process that Darwin described as "descent with modification? - Answer -The
characteristics of a species may change from generation to generation. This is
evolutionary change.
Carl Woese and his colleagues built a tree of life by comparing rRNA ribonucleotide
sequences of a variety of living organisms. What novel findings arose from this
analysis? - Answer -The most fundamental division among organisms is between
Archaea, Bacteria, and Eukarya. This was surprising to biologists, who thought of
Archaea as a specialized and relatively insignificant taxon.
Which of the following statements is true about the testing of scientific hypotheses?
(1) Hypotheses must be tested by carrying out experiments. (2) Hypotheses about
biological questions can be tested without collecting data. (3) Hypotheses must be
tested by making observations or measurements in a natural environment. (4)
Hypotheses may be tested by a combination of observation, measurement, and
, experimentation. - Answer -Hypotheses may be tested by a combination of observation,
measurement, and experimentation.
In an experiment, why is it important to control all variables except the one whose effect
is being investigated? - Answer -to reduce the chance that variables other the one being
investigated might influence the outcome of the experiment. If other variables are not
controlled, they may differ between experimental treatments.
In the same portion of rRNA, you find the following sequences: Land Plants:
AUAUCGAG Green Algae: AUAUGGAG Fungi: AUAUGGAC Based on these data,
which statement most accurately summarizes the evolutionary relationships of these
three types of organisms? - Answer -Fungi are more closely related to green algae than
to land plants.The rRNA sequence is more similar between fungi and green algae (one
ribonucleotide difference) than between fungi and land plants (two differences).
A knock-out allele is ______. - Answer -a mutated form of a gene that does not make a
functioning product. Knock-out alleles are also known as null or loss-of-function alleles.
Srb and Horowitz showed that ______. - Answer -mutations of a single gene resulted in
defects of one and only one enzyme. Their research supported the one-gene, one-
enzyme hypothesis.
What are the steps (in the correct order) that link a change in the base sequence of a
gene to a change in the phenotype of an organism like a mouse or a human? - Answer -
DNA—>RNA—>Protein. This is the central dogma, which summarizes the flow of
information in cells from DNA (genes) to proteins. For genes that encode RNAs that do
not function as mRNAs, only the DNA—>RNA step occurs.
The idea that the sequence of bases in DNA specifies the sequence of bases in an RNA
molecule, which specifies the sequence of amino acids in a protein, is _______. -
Answer -the central dogma; one of the basic underpinnings of biology.
The process of using the information in mRNA to synthesize a protein is ______. -
Answer -translation. The message in the mRNA must be translated into a protein.
According to the original central dogma, what macromolecule or phenomenon is directly
responsible for an organism's phenotype? - Answer -Proteins carry out the majority of
cell functions.
Consider the consequences of a mutation in the DNA template sequence 5'ATG3' to
5'TTG3': What is (a) the resulting change in the mRNA codon and (b) the effect on the
corresponding amino acid? - Answer -(a) CAU to CAA; (b) His to Gln
A point mutation that results in the substitution of one amino acid for another within a
protein is a ______. - Answer -missense mutation. The majority of point mutations do
not benefit the organism.
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