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questions in the back of the chapters and on

How are adaptations beneficial to organisms?

Adaptations help organisms survive and reproduce in a particular environment

Why was Darwin's acceptance of an ancient, continuously changing Earth so important in his development of his ideas about evolution?

Darwin hypothesized that species changed gradually, over long spans of time, in response to diverse and changing habitats

An adaptation is:

a heritable trait that confers a reproductive advantage on the individual possessing it

At the time Darwin voyaged on HMS Beagle, the popularly accepted theory in Europe that explained the origin of Earth's plants and animals held that the various species:

had been created rapidly by a divine creator a few thousand years before

What broad set of ideas was established by the work of Lamarck, Lyell, and Darwin?

Earth and its life are ancient and ever-changing; fossils document the evolution of life-forms over time

Blue-footed boobies have webbed feet, and are comically clumsy when they walk on land. Evolutionary scientists view these feet as:

the outcome of a tradeoff: webbed feet perform poorly on land, but are very helpful in diving for food

The core theme of biology is:


Aristotle believed that:

species are fixed (permanent) and perfect

Lyell's book Principles of Geology, which Darwin read on board the HMS Beagle, argued in favor of which concept?

Earth's surface is shaped by natural forces that act gradually and are still acting

Who developed a theory of evolution almost identical to Darwin's?


In artificial selection, humans provide the selective pressure for species to change and shape the evolution of various breeds. What provides the selective pressure in natural selection?

the environment

German shorthaired pointers, Scottish terriers, and Beagles are capable of interbreeding and producing viable, fertile offspring. The diversity seen in these breeds of dogs is the result of:

artificial selection

The breeding of plants and animals with desired traits by humans is called:

artificial selection

If members of a population have traits that are both heritable and variable among individuals, then:

advantageous traits will probably become more widespread in subsequent generations

Darwin inferred that there is a struggle for existence in which each individual's odds of surviving to reproduce are quite poor, based on the observation that:

natural population sizes usually stay about the same over long periods of time

"Differential success in reproduction" is the essence of:

natural selection

In natural selection, ____ determine which phenotypes are successful.

current conditions in the local environment

A number of mosquito populations today are resistant to specific insecticides that once were effective in killing them. Biologists believe that insecticide resistance evolved in mosquitoes because:

a few mosquitoes were probably resistant to the insecticide before it was used. These survived to reproduce and now the norm in populations that have been exposed to the chemical

Fossils are most likely to be found in:

sedimentary rock

What summarizes the order of appearance of major life-forms and the time at which life first appeared as documented by the fossil record?

prokaryotes, unicellular eukaryotes, multicellular eukaryotes, with the oldest life-forms appearing about 3.5 billion years ago

What best describes the fossil record?

the highly ordered sequence in which fossils are found in layers of sedimentary rock

Evidence from molecular biology supports the theory of evolution by showing that:

diverse organisms share many similar genes and proteins, and the similarity of these molecules is greatest when comparing closely related organisms

All known organisms use genetic information to produce protein molecules via the same genetic code. This finding strongly supports the hypothesis that:

all organisms are descended from one or a few common ancestors

The bones of the wings of bats are homologous to the bones of the____ of their ancestors.

front limbs

Organisms that possess homologous structures probably:

share a common ancestor that also had this structure

Members of the same population:

share a common gene pool

Microevolution, or evolution at its smallest scale, occurs when:

a population's allele frequencies change over a span of generations

____ and ______ generate variation in populations.

Mutation, sexual recombination

The ultimate source of all new alleles is:

mutation in parent cells (asexual organisms) or in cells that produce gametes (sexual organisms)

To be successful in evolutionary terms, an organism must:

pass its genes on to the next generation

Mate-attracting features such as the bright plumage of a male peacock is:

intersexual selection

Antibiotic resistance in bacteria is an example of what?

directional selection

Scientists have warned doctors of the danger of their increasing use of antibiotics for treating minor illnesses. They are concerned because:

strains of bacteria that are resistant to these drugs will become more widespread

Which genotype relative to the sickle-cell allele has the greatest reproductive success in regions where malaria is a common disease?

the heterozygous genotype

Under some conditions, heterozygotes have greater reproductive success than homozygotes. What is this called?

heterozygote advantage

Macroevolution can be defined as:

the appearance and extinction of species and the formation of major new branches on the tree of life

Lake Victoria is home to a group of related fishes known as cichlids. Hundreds of forms are present, differing slightly in their color patterns, habitat use, and feeding behavior. What is the best method for scientists to determine conclusively whether the fish are members of a population that has a lot of variation or members of entirely different species?

observing them together under natural conditions to see if they interbreed to produce fertile offspring

Speciation, or the formation of new species, is:

the bridge between microevolution and macroevolution

The ____ species concept is the most applicable to classifying species from the fossil record?


When a horse and a donkey mate, they produce infertile hybrids called mules. According to the ____ species concept, horses and donkeys are____

biological, different species

According to the biological species concept, a species is:

a group of populations whose members can interbreed in nature and produce fertile offspring

Often, the morphological species concept is used to define and describe species. Why?

this is the most convenient way of identifying species, and it is one of the few ways to identify fossil or asexual species

Two species of clams inhabit the same marine habitat along the Atlantic coast. One releases gametes into the water in early spring, and the second species releases gametes into the water in late summer. Which type of reproductive barrier is at work between these species?

temporal isolation

Three species of frogs all mate in the same ponds, but they pair off correctly because they have different calls. This is a specific example of a ____ barrier, called _____

prezygotic, behavioral isolation

Individuals of different species living in the same area may be prevented from interbreeding by responding to different mating dances. This is called:

behavioral isolation

Two rodent populations become separated when a large canyon develops in a previously unbroken forest. When is allopatric speciation between the two populations complete?

when the two populations evolve to be different enough so that they are incapable of interbreeding successfully when given the opportunity to do so under natural conditions, allopatric speciation is complete

What is the first step in allopatric speciation?

geographic isolation

Uplift and formation of a mountain range divides a freshwater snail species into two isolated populations. Erosion eventually lowers the mountain range and brings the two populations together again, but when they mate, the resulting hybrids all produce sterile young. This scenario is an example of:

allopatric speciation

In the mountains of the southeastern United States, there are may similar but distinct salamander species that are restricted to particular mountaintops or ridge systems. They are found in patches of suitable high-elevation habitat, separated by unsuitable lowland areas. This distribution pattern indicates:

numerous allopatric speciation events

Sympatric speciation typically occurs through ___ and through _____

polyploidy in plants, habitat differentiation in animals

Speciation without geographic isolation is called ___ speciation


Sympatric speciation is:

the appearance of a new species in the same area as the parent population

Organisms that possess more than two complete sets of chromosomes are said to be:


What do Dodd's experiments with fruit flies indicate?

reproductive barriers will arise most quickly if isolated populations experience and become adapted to differing environments

In a hybrid zone, ___ can occur if the reproductive barrier between two species is weak, as seen among cichilids in the murky waters of modern Lake Victoria.


Biologists have found more than 500 species of fruit flies on the various Hawaiian islands, all apparently descended from a single ancestor species. When this ancestor colonized the island chain, it found few competitors: many insect and fly families present in other regions are absent from the isolated Hawaiian islands. This example illustrates:

adaptive radiation

Earth probably formed ___ years ago, and the first life evolved as early as ____ years ago

4.5 billion, 3.9 billion

The "big bang" that produced the universe is thought to have occurred:

10 to 20 billion years ago

What is thought to have been the first step in the origin of life?

formation of organic monomers such as amino acids

Miller was the first to show that:

amino acids and other organic molecules could have been generated on a lifeless Earth

Protobionts are:

spheres with lipid membranes that concentrate solutes and can even carry out simple metabolic reactions if provided with enzymes

Hot sand, clay, or rock may have played an important role in the origin of life because:

evaporation of seawater from these surfaces could have concentrated monomers, leading to the formation of polymers through dehydration synthesis

A current leading hypothesis about the first system of inheritance in the earliest life forms involves:

self-replicating RNA molecules aided by ribozymes

The earliest cells were most likely:


About 2.2 billion years ago, oxygen released by early ____ became fairly abundant in the atmosphere, enabling the evolution of _____

photosynthesis, cellular respiration

The technique called radiometric dating is based on:

the steady, clocklike decay of certain radioactive isotopes over time

The C14C12 ratio can be used to date fossils that are up to approximately how old?

75,000 years

If you want to see a dinosaur, it would be best to set the controls of your time machine for the:

Mesozoic era, 150 million years ago

The correct order of the geologic eras, from most ancient to most recent, is:

Precambrian, Paleozoic, Mesozoic, Cenozoic

Earth's continents and seafloors together form a thin outer layer of the planet called the:


The Himalayas are an example of a mountain range formed as a result of:

the collision of two continental plates

The end-Cretaceous extinctions were followed by the:

adaptive radiation of mammals

Homeotic genes are responsible for:

determining the location and pattern of structural features such as limbs

Fish that were ancestral to the first amphibians may have had limbs that were used for moving through underwater vegetation, and were later adapted for use in walking on land. If so, the limbs were an example of:

an exaptation

The concept of ____ suggests that feathers originally evolved ____

exaptation, for some other function and only later became adapted for flight

Structures that evolved from the same structure in a common ancestor are:


The scientific study of the diversity of organisms and their evolutionary relationships is called:


Systematic biologists have used a wide variety of traits to reconstruct the phylogenies of particular groups of organisms. Which type of trait can also be analyzed to estimate the divergence times between taxa?

gene sequences

Members of what was once the kingdom Monera are now divided into two major domains called the:

Archaea and Bacteria

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