biol 13

Every few years a giant axe chops off the head of every person who is over 6 feet tall. How will this affect the human population?

Alleles that promote "tallness" will decrease in frequency.

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?

Each patient's viral population would be unique, specifically adapted to deal with—and overcome—his or her unique immune system responses.

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

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

Based on the video, what can you infer about speciation--the process by which one species splits into two or more species?

Physical separation of populations is often part of the speciation process

Genetic drift is a process based on _____.

the role of chance

A mutation occurs when _____.

there is a change in the DNA sequence of a gene

Scientists studying evolution on the Solomon Islands described which animal as the 'poster child' for the biological species concept?

white-eye bird

Evolutionary biologists studying the evolution of lizard horn length found __________.

that lizard horn length evolved as a defense mechanism against predators

The population of American bison used to number in the millions of animals. Hunting and other problems greatly decreased the number of bison to about 1,000 animals. But today, the numbers are recovering to estimates of more than 200,000 animals. This crash in the population of bison and recent recovery is a good example of _____.

the bottleneck effect

Click on the diagram to start the animation. Which of these gametes contain one or more recombinant chromosomes?

B, C, F, and G

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

True or False. In the example described in the tutorial, the red amoebas survived the catastrophic event, and all future generations of amoebas were red because the red amoebas had a higher reproductive rate than the blue ones.

False

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?

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

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

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

Which one of the following was an assumption of Charles Darwin's theory of natural selection?

Populations produce more offspring than their environment can support

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

The HIV virus has an extremely high rate of mutation.

The title of Darwin's book in which he presented evidence that each living species descended from a succession of ancestral species is __________.

The Origin of Species by Means of Natural Selection.

There is a group of small fish living in a lake with a sandy bottom. Most of the fish are light brown, but about 10% are mottled. These fish are normally prey for large birds that live on the shore. A construction company dumps a load of gravel in the bottom of the lake, giving it a mottled appearance. Which of these statements presents the most accurate prediction?

The proportion of mottled fish will increase over time.

Natural selection is best described as _____.

a filtering process that fine-tunes the traits of populations by sorting among existing, randomly produced variations

Why did the biologists consider a frog that they found to be a new species?

genetics

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

has more effect on the evolution of a small population.

Where are the Solomon Islands located?

in the South Pacific

Homologous pairs of chromosomes are lined up independently of other such pairs during _____.

metaphase I

Generation-to-generation change in the allele frequencies in a population is _____.

microevolution

A process in which organisms with certain inherited characteristics are more likely to survive and reproduce than are individuals with other characteristics is called _____.

natural selection

What process is illustrated by this animation?

natural selection

Crossing over, resulting in an increase in genetic variation, occurs between _____.

nonsister chromatids of homologous chromosomes

What do we call scientists who study fossils?

paleontologists

Which of the following is an example of natural selection that has been seen in our lifetime?

the evolution of antibiotic-resistant bacteria

Imagine that a new population of humans is established on a new planet from ten randomly selected people in your biology class. Over thousands of years, the descendants of those ten people reproduce and prosper, but do not reflect well the diversity of humans on Earth. This change in the diversity of people on the new planet is an example of _____.

the founder effect

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.

In human gamete production there is an average of _____ crossover events per chromosome pair

2-3

Which of these individuals is a homozygous genotype?

AA

Which of the following events could NOT be caused by a population bottleneck?

Increased population size

Which of the following statements about the amoeba population described at the end of the tutorial is true?

It is more vulnerable to extinction due to lack of genetic variation.

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

Which of the following is the study of the geographic distribution of species on Earth?

biogeography

Modern travel along with migration reduces the probability of _____ having an effect on the evolution of humans.

genetic drift

In evolutionary terms, an organism's Darwinian fitness is measured by its __________.

contribution to the gene pool of the next generation

Click on the diagram to start the animation. This animation illustrates _____ as it occurs during _____.

crossing over ... prophase I

The evolution of populations due to chance is

genetic drift.

The wing of a bat is homologous to the _____ of a whale.

flipper

All the genes in a population are that population's _____.

gene pool

According to current evolutionary theory, which of the following is true?

Populations are the units of evolution