1. You have two pea plants, one of which is homozygous dominant
(AA) for a gene controlling pea color, and another which is homozygous
recessive for the same gene (aa). You cross the two plants and
collect the progeny plants. You allow one of these plants to self-pollinate
and collect the progeny plants. Which of the following is true
about those plants?
a. They are all identical in genotype
b. They are all identical in phenotype c. Those with the dominant phenotype outnumber those with
the recessive phenotype by 3:1
d. Those with the recessive phenotype outnumber those with the
dominant phenotype by 3:1
e. The plants are all sterile
2. You have a plant that is tall with red flowers
which you allow it to self-pollinate. You collect the seeds and
grow plants from them. You find that the plants which develop
are of several types: tall with red flowers, short with red flowers,
tall with white flowers, and short with white flowers. These types
arise in a ratio of 9:3:3:1. Assuming that a gene called T controls
plant height and R controls flower color, what is the genotype
of the original plant?
a. Can't be determined from the available information
b. RR TT
c. Rr TT
d. RR Tt e. Rr Tt 3. Gregor Mendel's theory of genetic inheritance
assumes several things about the behavior of what we now call
genes. Which of the following did Mendel assume to be true?
a. Genes are carried on chromosomes b. Genes segregate independently in crosses
c. Recombination occurs at random positions between genes
d. Genes are made of deoxyribonucleic acid
e. Genes encode protein products 4. In class we talked about the concept of epistasis.
Which of the following is an example of epistasis?
a. A gene controlling flower color can result in either red or
white flowers, depending on its DNA sequence b. The B gene controls coat color in labradors, yet combining
homozygous recessive forms of another gene with any combination
of B alleles results in a yellow dog c. The physical distance between two genes on a chromosome
is directly related to the frequency of recombination between
them
d. A pea plant with white flowers when allowed to self-pollinate
produces only plants with white flowers
e. Crossing a plant with red flowers by a plant with white flowers
produces plants with pink flowers 5. A male member of the class discovers that some
of his mother's maternal uncles suffered from pattern baldness,
as do some of her brothers. He has an older brother who also suffers
from pattern baldness. None of the women in the family has this
problem. He is worried that he will soon have to contact "Hair
Club for Men", so you investigate and find that there is
no record of pattern baldness in his father's family. You quickly
inform him that:
a. He has nothing to worry about, he couldn't have inherited pattern
baldness
b. He has one chance in four of inheriting pattern baldness c. He has one chance in two of inheriting pattern baldness d. He will certainly inherit pattern baldness
e. You don't have enough information to tell him if he might inherit
pattern baldness 6. Early experiments testing the identity of the
genetic material were done by Griffith and by the trio of Avery,
MacLeod and McCarty. The latter group improved on the work of
Griffith in one important way which allowed them to draw an important
conclusion about the genetic material. What was that improvement?
a. They used two forms of the bacterium Streptococcus pneumoniae,
the smooth and rough types
b. They heat killed the bacterium c. They used purified DNA in their experiments d. They tested the ability of cells to kill mice when
injected
e. They found that smooth and rough types of the bacterium rarely
interconverted spontaneously 7. The result of experiments performed in the late
1950s indicated that the replication of DNA was "semi-conservative".
What does this mean?
a. Only part of each DNA strand is replicated b. The two double-stranded molecules generated by replication
both contain one new and one old strand
c. One of the two double-stranded molecules generated by replication
is entirely new
d. One strand of each DNA molecule is destroyed during replication,
and one is retained
e. After some replication events the original DNA molecule remains
unchanged 8. You identify a short region of RNA within a
longer mRNA with the following sequence:
5'-GAUUACGCAUCC-3'
What is the sequence of the DNA region from which this is copied
(that is, the strand which acts as template for the synthesis
of this RNA)? a. 5'-GGATGCGTAATC-3' b. 5'-TCGGCATACGAA-3'
c. 5'-CTAATGCGTAGG-3'
d. 5'-GGTAGCGATTAC-3'
e. 5'-GATTACGCATCC-3' 9. The "genetic code" is the list of
code words ("codons") in RNA which specify particular
amino acids in proteins. Which of the following statements about
the genetic code is correct?
a. The genetic code is degenerate
b. Codons are groups of three nucleotides
c. Groups of codons specifying the same amino acid differ in the
third position
d. Three of the codons specify peptide termination e. All of the above 10. Watson and Crick proposed a structure for deoxyribonucleic
acid in 1953. Of the following statements which is not a correct
description of that structure?
a. The structure involves four nucleotides, symbolized as A, G,
C and T
b. Nucleotides are linked together by phosphodiester bonds between
the 5' and 3' positions of deoxyribose c. The two strands of DNA are parallel, that is they run
in the same chemical direction d. The phosphates in nucleotides are on the outside of
the structure
e. The overall structure of the molecule is a double helix 11. Genes encode proteins, but those protein products
are not necessarily expressed in all circumstances or by all cells.
The lac operon provides a simple system to study mechanisms of
gene regulation. Which of these statements about the lac system
is correct?
a. The genes of the lac system are organized as an "operon"
b. A repressor protein binding to the lac mRNA can stop it from
being translated
c. Binding of the CAP·cAMP complex to the lac DNA can stimulate
transcription of the lac genes
d. a and b e. a and c 12. Genes can be regulated in various
ways. In class I discussed several mechanisms of gene regulation
which are also mentioned in Starr & Taggart. Which one of
these statements about genetic control is incorrect?
a. Transcription of some genes is regulated
b. Genes can be regulated by processing of the mRNA after transcription
c. In some cases the ability to translate the mRNA is regulated
d. Some genes are regulated by the specific degradation of their
protein product e. In no case is a gene regulated by more than one of
these mechanisms 13. Restriction enzymes are one of the
critical elements of the technology we call "genetic engineering".
These enzymes are important because:
a. They restrict the growth of potentially harmful bacteria used
in "gene cloning" experiments b. They allow scientists to break DNA down into fragments c. They modify DNA so that it can not be broken when
it enters a foreign host
d. They show no substrate specificity whatsoever
e. They join two DNA molecules together by forming new phosphodiester
bonds 14. A new technique called Polymerase Chain Reaction
(PCR) has revolutionized molecular biology. The technique can
be used to generate fragments of DNA beginning and ending at any
position within a larger fragment. What feature of PCR provides
this ability?
a. DNA polymerase repeatedly copies DNA strands b. Two short DNA primers define where replication begins c. The amount of product formed increases geometrically
d. The DNA products are digested with restriction enzymes at the
end of PCR
e. DNA polymerase initiates replication at a promoter 15. In "The Origin of the Species" Darwin
proposes a mechanism to explain the origin of the biological diversity
on Earth. Which of these statements about Darwin's theory is correct?
a. Darwin believed that his theory of evolution invalidated all
religious descriptions of the origin of biological diversity
b. Darwin argued that evolution occurred as a result of inheritance
of acquired characteristics
c. Darwin invented the concept of evolution d. Darwin argued that competition among individuals for
limiting resources would select for changes in the frequencies
of certain genetic traits e. Changes in DNA sequence are heritable 16. Catastrophism is a theory which was put forth
to explain the fossil record which shows that over time species
have been eliminated and replaced by other species not previously
present in the record. How does Catastrophism explain this fact? a. Previously existing unabundant species repopulate earth
after most plants and animals are killed by a catastrophe b. Those plants and animals which survive have special
adaptive traits
c. New species arise because competition between individuals selects
for genetic changes
d. The catastrophe selects for survival of the animals and plants
which are fittest
e. Evolution occurs gradually during periods between catastrophes 17. Modern evolutionary theory differs from the
theory created by Darwin in many ways. What idea proposed by modern
evolutionary theory was not a part of Darwin's theory?
a. Evolution occurs because of intense competition among individuals
b. Evolution occurs because selection favors the survival of the
fittest c. The processes which drive evolution are often random,
completely unrelated to fitness d. Evolution has occurred in all parts of the world
e. Evolution does not involve inheritance of acquired characteristics 18. The Hardy-Weinberg Rule describes the behavior
of genetic traits in a population of individuals in which there
are two forms of an allele present. Why is the Hardy-Weinberg
Rule useful to population biologists?
a. They can use it to predict how the frequencies of alleles will
change as environmental conditions change b. They can use it to determine how selective pressure
on a population is forcing a change in allele frequencies c. It is not useful to population biologists
d. They can use it to determine the frequency of epistasis in
a population
e. They can use it to calculate the frequency of each allele in
a population 19. Microevolution can occur as a result of various
mechanisms which cause changes in allele frequency in a population.
Which of the following is an example of one of those mechanisms
called "genetic drift"
a. Selection operating on a population may tend to favor intermediate
phenotypes b. After a population experiences an event involving massive
death the allele frequencies in the population may have changed
drastically c. Individuals moving between two populations tend to
reduce the differences in allele frequencies between the two populations
d. Selection operating on a population may tend to favor either
of two extreme phenotypes
e. Two allelic traits may be stabilized in a population because
the heterozygote have some selective advantage 20. The story of the peppered moth and the effect
of environmental pollution on the frequency of allelic types in
the English midlands is a classic of population biology. Which
of these statements about the peppered moth story is not correct?
a. Light-colored moths decreased in number because of the increased
contrast with darkened tree bark
b. The effect of environmental changes on survival of the moths
were tested by controlled experiments c. The change in frequency of the two types of moths occurred
because of competition between the moths for a limiting resource d. When pollution was reduced the frequency of lightation
again became adaptive
e. Changes in the frequency of the two types of moths probably
depended on their being preyed on by birds 21. The concept of "species" has changed
over time. What is the essential aspect of the "biological
species concept"?
a. Species all share similar behaviors and appearance
b. All individuals of a species are descended from a common ancestor
c. Individuals in a species all occupy the same role in the ecology
of their region d. Individuals of a species normally mate and produce
fertile offspring in the wild e. All individuals in a species share a common body plan
or structure 22. The "Central Dogma" of molecular
biology states:
a. All aspects of living things can be explained by interactions
among molecules b. DNA codes for RNA which in turn codes for proteins c. Deoxyribonucleic acid is the genetic material
d. The expression of genes must be regulated so that they are
expressed only in appropriate cells or under appropriate circumstances
e. Dexyribonucleic acid is chemically stable 23. In the Hershey-Chase experiment bacteriophage
were labeled with radioactive forms of sulfur (35S) or phosphorus
(32P). These atoms were used to follow the bacteriophage protein
and DNA as the phage infected a culture of bacteria. The conclusion
of the experiment was that:
a. Radioactive elements intefere with virus propagation
b. Proteins enter the bacteriophage by a different route than
does DNA
c. After removing the DNA from a bacteriophage it can not infect
a bacterium
d. DNA is copied into proteins which are injected into the bacterium e. DNA must be the genetic material since it enters the
bacterium during infection 24. The ribosome plays a fundamental role
in the process of translation. What is that role?
a. It is responsible for making an RNA copy of the DNA genome b. It is the site of decoding of messenger RNAs into proteins c. It regulates the rate of initiation of RNA synthesis
on various genes
d. It is the site at which copies of DNA are synthesized
e. It binds to genes to repress synthesis of messenger RNAs 25. Beginning around the year 1800 scientists became
increasingly convinced that species have changed over time. Which
of the following was not among the evidence supporting this conclusion?
a. Unexpected similarity in structure which had no obvious purpose
(for example, similarity between hands, bat wings, and whale flippers)
b. The existence of increasingly complex fossils over time in
the geologic record
c. The existence of unique species in isolated locations, (for
example, on islands) d. The inability to find intermediate types between species
over time ("missing links") e. None of the above