Chapter 23
A population is in Hardy-Weinberg equilibrium. The gene of interest has two alleles, with 16% of the population portraying the recessive phenotype. Which percentage of the population is heterozygous?
48%
Fruit flies are beginning to live & mate on different types of fruit on the floor of the Amazon. Bigger fruit flies prefer rotting mangos, while smaller fruit flies prefer rotting bananas. What type of reproductive barrier is this?
Habitat Isolation
Which method uses dideoxynucleotides and Northern blotting to determine the DNA sequence?
Sanger Method
A bird that can easily outcompete other birds for food and that can produce many eggs has a high
fitness
Which of these is the smallest unit that natural selection can change?
a. a species' gene frequency
b. a population's gene frequency
c. an individual's genome
d. an individual's genotype
e. an individual's phenotype
b. a population's gene frequency
If, on average, 46% of the loci in a species' gene pool are heterozygous, then the average homozygosity of the species should be
54%
The pollen (sperm) of a flowering plant cannot fertilize the egg cell of a nearby flowering plant of its kind. What type of reproductive barrier is this?
Gametic Isolation
Which of the following sequences is most likely to be cut by a restriction enzyme?
AATTCT
TTAAGA
AATATT
TTATAA
AAAATT
TTTTAA
ACTACT
TGATGA
AATATT
TTATAA
Genetic variation can arise from a random change in the DNA of a gene. The change is called a(n)
mutation
The Darwinian fitness of an individual is measured most directly by
the number of its offspring that survive to reproduce.
In a hypothetical population's gene pool, an autosomal gene, which had previously been fixed, undergoes a mutation that introduces a new allele, one inherited according to incomplete dominance. Natural selection then causes stabilizing selection at this locus. Consequently, what should happen over the course of many generations?
The proportions of both types of homozygote should decrease.
The proportion of the population that is heterozygous at this locus should remain constant.
The genitalia of the male damselfly varies in shape. Certain males can only hold onto & mate with females whose genitalia fit. What type of reproductive barrier is this?
Mechanical Isolation
Which of the following is not needed for PCR
helicase
primers
DNA polymerase
nucleotides
helicase
No two people are genetically identical, except for identical twins. The chief cause of genetic variation among human individuals is
the reshuffling of alleles in sexual reproduction.
The DNA polymerases of all cellular organisms have proofreading capability. This capability tends to reduce the introduction of
genetic variation by mutations.
A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. ____
What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait (aa) has not changed over time?
The two phenotypes are about equally adaptive under laboratory conditions.
Two populations of the same species over time grow distant from one another. At what point will these two populations be considered different species?
When they are no longer able to interbreed
Which of the following is required to make complementary DNA (cDNA) from RNA?
restriction enzymes (endonucleases)
gene cloning
DNA ligase
reverse transcriptase
reverse transcriptase
Natural selection changes allele frequencies in populations because some ____ survive and reproduce more successfully than others.
Individuals
What are the roles of ATP and NADPH in photosynthesis?
ATP and NADPH are forms of chemical energy produced from the light dependent reactions to be used in the light independent reactions that produce sugars.
You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice that the viability of the flies has decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to
a. cross your flies with flies from another lab.
b. reduce the number of flies that you transfer at each generation.
c. transfer only the largest flies.
d. change the temperature at which you rear the flies. e. shock the flies with a brief treatment of heat or cold to make them more hardy.
a. cross your flies with flies from another lab.
A population of rabbits lives in a forest in the Southeastern United States. A large group of rabbits is cut off from the population when a six-lane highway is built through the forest. Over many generations, the large group of rabbits begins to develop darker fur in response to the dominant foliage on one side of the highway. When rabbits from the two populations are brought together, they no longer reproduce with each other. What kind of speciation does this represent?
Allopatric
What do sticky ends do?
They can hydrogen bond to other cut DNA strands until ligase seals them permanently
Which of these is the smallest unit upon which natural selection directly acts?
a. a species' gene frequency
b. a population's gene frequency
c. an individual's genome
d. an individual's genotype
e. an individual's phenotype
e. an individual's phenotype
Which naturalist synthesized a concept of natural selection independently of Darwin?
Alfred Wallace