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46 terms

Biology Test F (Ch.16)

Which of the following statements describes what all members of a population share?
They are members of the same species
If an allele makes up one fourth of a population's alleles for a given trait, its relative frequency is
25 percent
In many kinds of organisms, most heritable differences are due to (hint: compares yourself to a family member)
gene shuffling during gamete formation
A single-gene trait that has two alleles and that shows a simple dominant-recessive pattern will result in
two phenotypes
When individuals at only one end of a bell-shaped curve of a phenotype frequencies have high fitness, the result is
directional selection
When individuals with an average form of a trait have the highest fitness, the result is
stabilizing selection
Genetic drift tends to occur in populations that
are small
The type of genetic drift that follows the colonization of a new habitat by a small group of individuals is called
the founder effect
The allele frequencies of a population are more likely to remain unchanged if
all mating is random
What situation might develop in a population having some plants whose flowers open at midday and other plants whose flowers open late in the day?
temporal isolation
The Galapagos finch species are an excellent example of
The combined genetic information of all members of a particular population is the population's
gene pool
A change in the sequence of nucleotides within a gene's DNA is called a
The distribution of phenotypes for a typical polygenic trait can often be expressed as
a bell-shaped curve
Natural selection acts directly on
The situation in which allele frequencies of a population remain constant is called
genetic equilibrium
One of the conditions required to maintain genetic equilibrium is
no movement into or out of the population
The separation of populations by barriers such as rivers, mountains, or bodies of water is called
geographic isolation
A factor that is necessary for the formation of a new species is
reproductive isolation
Which is the first step that occurred in speciation of the Galapagos finches?
arrival of the founding population
What is the name of the ancient land mass made up of all the combined continents?
What term describes the assumed evolutionary relationship between very different organisms? (hint: evolutionary "tree")
Dr. Lynn Margulis argued that organisms ate each other, didn't digest what they ate, and that is the explanation for how macroevolution produced the
eukaryotic cell
Which of the following is a weakness in the dating of fossils?
all are weaknesses
Sedimentary rock is formed from
small particles of sand, silt, and clay
What proportion of all species that ever lived has become extinct?
most than 99 percent
The basic divisions of the geologic time scale from larger to smaller are
eras and periods
The Mesozoic Era occurred
after the Paleozoic Era
What prevents organic molecules from forming on their own and remaining intact today?
atmospheric oxygen is too reactive
Which of the following functions can RNA perform under certain conditions?
all of the above
The process by which two species, for example, a flower and a pollinating insect, evolve in response to each other is called
Examples of fossils include preserved
all of the above
In the past, mass extinctions encouraged the rapid evolution of surviving species
by making new habitats available to them
Most fossils form in
sedimentary rock
The length of time required for half of the radioactive atoms in a sample to decay is its
To compare the relative ages of fossils, scientists sometimes use an easily recognized species called a(n)
index fossil
Earth's most recent era is
WHy did oceans not exist on Earth nearly 4 billion years ago?
water remained a gas because Earth was very hot
A single species that has evolved into several different forms that live in different ways has undergone
adaptive radiation
Sharks, dolphins, and penguins all have streamlined bodies and appendages that enable them to move through water. These similarities are the result of
convergant evolution
Which statement about gene pools is typically true?
they contain two or more alleles for each gene
The genetic equilibrium of a population can be disturbed by each of the following EXCEPT
a large population size
One necessary condition for the evolution of the first life on Earth was
the presence of liquid water
The first organisms on Earth were most likely today's