MB 13

Which of the following lists of assumptions was part of Charles Darwin's theory of natural selection?

1. Organisms vary in heritable ways. 2. Some traits improve the survival and reproduction of individuals who possess them. 3. Populations produce more offspring than their environment can support, so individual organisms must compete for limited resources. 4. Earth and its life are very old.

Darwin inferred that those organisms with traits best suited to the environment tend to leave more ---- than other members of a population.

offspring

Gene flow, natural selection, genetic drift: A prominent tail helps the peacock attract a mate.

Natural selection

Gene flow, natural selection, genetic drift: The bird's beak is well-suited for cracking seeds.

Natural selection

Which best describes how an organism's Darwinian fitness is measured? - the organism's reproductive success relative to other individuals in the same population - the number of offspring a species can produce compared to other species in the same community - the organism's strength and ability to dominate other individuals within the same population - overall health or condition of the organism

the organism's reproductive success relative to other individuals in the same population

All of life is related through common ancestry, accounting for the ---- of life.

unity

Imagine that four people are infected with HIV from a common source (an infected blood sample). Initially, the patients' HIV populations are genetically identical. By the time they develop full-blown AIDS, how would the viral populations of the four patients compare?

A). Each patient's viral population would be unique specifically adapted to deal with- and overcome- his or her unique immune system response.

HIV has become an important source of mortality for humans. If AIDS persists as a major factor for humans for many generations in the future, natural selection theory predicts that

Any heritable traits that help humans survive and reproduce in the presence of AIDS should become more frequent over time.

Remember that color is an inherited trait in beetles. Which of the following is an example of natural selection?

B). Green beetles leave more offspring than brown beetles because they are better at finding food.

The human immune system cannot effectively suppress the HIV virus on its own. What key feature of HIV makes it so hard to beat?

B). The HIV virus has an extremely high rate of mutation.

As proposed by Darwin, what sorts of traits are favored by natural selection?

D). Heritable traits that help individuals survive and reproduce more successfully than others in the same population.

In a species of snail, dark-shelled individuals are better hidden from bird predators in the shady forest, while light-shelled individuals are better hidden in well-lit brushy edge areas. If there were no areas of intermediate brightness in this habitat, which type of selection would act on shell color in these snails?

Disruptive Selection

What broad set of ideas was established by the work of Lamarck, Lyell, and Darwin? - Fixed (unchanging) species live on an Earth that is about 6,000 years old. - Earth and its life are ancient and ever-changing; fossils document the evolution of life-forms over time. - As shown by fossils, life evolves. All changes have occurred within the past 6,000 years - the age of Earth. - Life evolves through inheritance of mutations in DNA.

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

Gene flow, natural selection, genetic drift: New individuals move into a population.

Gene flow

Gene flow, natural selection, genetic drift: By chance, some wildflowers in this population reproduce, while others do not.

Genetic drift

The evolution of populations due to chance is

Genetic drift

In a population with brown and green alleles for color, genetic drift

Has more effect on the evolution of a small population.

Small lizards have difficulty defending their territory, but large lizards are more likely to be preyed upon by owls. Which type of selection would act on body size in these lizards under these conditions?

Stabilizing Selection

The forelimbs of humans, cats, and bats have a number of detailed similarities in their construction. What best explains these similarities? - The forelimbs are similar because all of these organisms inherited the basic forelimb design from a common ancestor. - The forelimbs are similar because there is only one workable way to construct a useful arm, leg, or wing. - The similarities are coincidental. - The forelimbs are similar because of adaptation through the process of natural selection.

The forelimbs are similar because all of these organisms inherited the basic forelimb design from a common ancestor

Two key observations underlying natural selection are that members of a population vary in their ----- ---- and that all species can produce more offspring than the environment can support.

inherited traits

The phrase Darwin used to describe his broad theory of evolution is ''descent with

modification

Darwin proposed a mechanism for how evolution occurs, which he called ------ -------.

natural selection

Gene flow, natural selection, genetic drift: Camouflage enables this insect to evade predators.

natural selection

If color is an inherited trait in beetles, and birds are more likely to eat brown beetles than green beetles,

the frequency of the green allele will increase.

Natural selection is best described as _____.

C). A filtering process that fine-tunes the traits of populations by sorting among existing, randomly produced variations.

Color is an inherited trait in beetles. If brown beetles move into a population from a nearby island, which of the following statements is correct?

C). Gene flow causes the frequency of the brown allele to increase.

Certain bacterial strains have traits that allow them to resist the effects of antibiotic drugs. How do the resistance traits arise in a bacterial population, and under what circumstances will the resistance traits be most common? - The resistance traits are produced by chance mutations and are present to varying degrees in most bacterial populations. Resistance traits will be most prevalent, however, in bacteria that are chronically exposed to antibiotic drugs. - The resistance traits arise as the immune systems of the bacteria detect and respond to the drugs. Therefore, individual bacteria become more and more resistant if they are exposed to antibiotic drugs. - Resistance traits are produced because antibiotic drugs cause mutations in bacterial cells. The resistance traits only occur in the presence of antibiotics. - The resistance traits are developed by bacteria when they detect the drugs in their environment, through mutations that counteract the drugs' effects. Thus, they are most common wherever the drugs are present.

The resistance traits are produced by chance mutations and are present to varying degrees in most bacterial populations. Resistance traits will be most prevalent, however, in bacteria that are chronically exposed to antibiotic drugs.

This unequal reproduction in a population leads to the gradual accumulation of ------ to the environment.

adaptations

The ----- of life arises from the adaptation of species to different habitats over long spans of time.

diversity