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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


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