chapter 15 mastering biology

directional selection

( 1 direction) Form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve

stabilizing selection

Natural selection that favors intermediate variants by acting against extreme phenotypes

There are several types of bacteria that are resistant to most, if not all, antibiotics available. Which of the following best explains the mechanism of this resistance.

One or a few bacteria gain a mutation that makes them resistant to the antibiotic. These bacteria survive and reproduce in the presence of the antibiotic

What does it mean to say that pigweed is resistant to herbicide?

Pigweed plants thrive despite the application of herbicides intended to kill them.

biological species concept

Species is a group of populations whose members have the potential to produce fertile offspring.

gene flow and genetic drift

gene flow is going in and out ( mating new genes) genetic drift is changes happening with in a population (wolves having thinner hair overtime due to weather)

some flowers IN a population reproduce others do not

genetic drift

In a population of 100 hamsters, there are 30 total alleles for black fur. What is the frequency of the black fur allele?

Correct. If there are 100 hamsters, there are 200 total alleles. Dividing 30 by 200 gives 0.15.

The evolution of populations due to chance is

Genetic drift describes the evolution of a population due to chance.

new individuals in a population

gene flow

disruptive selection

Favors individuals at both extremes of the phenotypic range

How do founder effect, genetic drift, and a bottleneck relate to each other?

Founder effect and bottleneck are types of genetic drift. Genetic drift doesn't have to be caused by a founder effect or a bottleneck, but these are two specific examples of genetic drift.

Why is natural selection based entirely on reproductive success?

The more times an allele is passed on, the more common the allele becomes. In the next generation, the same successful allele will result in each of the offspring having many children as well.

Pigweed plants thrive despite the application of herbicides intended to kill them.

The population has evolved.

camouflage against predators

natural selection

peacocks tail

natural selection