Chapter 11

What is the strategy behind combination drug therapy?

A greater number of changes are required in genetic material for resistance to develop if a greater number of drugs are used.

How is artificial selection different from natural selection?

Artificial selection is selection by human choice rather than environmental change.

Snakes are reptiles. Most reptiles have limbs. What relationship probably exists between snakes and limbed reptiles?

Being legless offered an advantage in one environment that allowed snakes to evolve from limbed reptiles.

You wish to replicate the experiment with fruit flies and alcohol. You expose some flies to alcohol and they all die. Which is the most likely reason your experiment was not successful?

You started with such a small population of flies that none of the flies had the tolerance allele.

Which situation would be most likely to lead to evolution in a population of plants?

drought

A population of foxes lives in an area in which the average winter temperature has been dropping for several years. Which adaptation would be most likely?

he exact adaptation depends on the genetic variation present in the 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 causes both extreme phenotypes (light and dark shells) to be favored over the intermediate phenotype.

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 does not change the mean of the population; only the extreme phenotypes (large and small lizards) become less common

Consider the adaptation to alcohol experiments presented in the text. In a high alcohol environment, what changes occurred in the fruit fly allele that produced the fast alcohol-metabolizing enzyme?

The allele became more frequent in the population over time. The fast-metabolizing enzyme is adaptive in the high alcohol environment. Therefore flies with this allele have more offspring and the allele increases in frequency in the population.

What type of selection relates to the average birth weight of humans babies?

stabilizing selection

How would evolutionary biologists define the fitness of an organism?

the ability of an individual to survive and reproduce

Which action should you take in order to breed a line of horses with long ears?

Find two horses with longer than usual ears and mate them.

If a population of fruit flies is exposed to a food source with high alcohol content, what would happen to the population?

Individuals who are not tolerant of the ethanol would die, and individuals who are naturally tolerant would survive.

You are culturing bacteria from a source that has never been exposed to antibiotic. Could any bacteria in the population have the trait of resistance?

It is possible, but not definite, that some bacteria in the culture have the trait even without exposure.