Deck 11: An Evolving Enemy: Natural Selection

Question 1

Which sequence of events describes natural selection?

A) A population of a mammal species varies in the length of their legs; water levels rise and the habitat becomes swampy; the individuals with shorter legs are better able to swim to food; the population evolves to become shorter-legged.
B) A population of a mammal species lives near the water; water levels rise and the habitat becomes swampy; the animals have trouble moving in the water; the population changes to a shorter-legged type so they can move more easily in the water.
C) Water levels rise, and a habitat becomes swampy; a population of a mammal species on high ground observes the change; individuals with shorter legs migrate to the area.
D) A population of a mammal species lives near the water; water levels rise and the habitat becomes swampy; the act of swimming shortens the legs of the mammals; the offspring of the mammal species have shorter legs.

Answer 1

A

Question 2

What kind of bacterial variant would be most likely to survive in the human digestive system?

A) a variant that thrives at temperatures close to 100°C
B) a variant with a coating that is resistant to an acidic environment
C) a variant that reproduces slowly
D) a variant that easily attaches to hard surfaces

Answer 2

B

Question 3

What is the primary body part affected by tuberculosis?

A) the liver
B) the muscles
C) the immune system
D) the lungs

Answer 3

D

Question 4

True or false: Natural selection is only one of several possible causes of evolution.

Question 5

True or false: Any individual organism has the potential to evolve if it's given enough time and possesses a mechanism to generate variation.

Question 6

After a rapid change in climate, one population of bird quickly adapts to the change, but others in the area do not. What could you conclude about the quickly adapting population?

A) They had a greater need to evolve than the other population.
B) They already had some alleles in their genome that were adaptive in the new environment.
C) They reproduced more slowly than the non-adapting population.
D) They had a higher rate of mutation than the other population.

Question 7

You notice that some squirrels in your neighborhood have a much darker coat color than most of the other squirrels. Is this darker color an adaptation?

A) Yes, all variations are adaptations.
B) No, adaptations are traits developed when they're needed to help an organism survive.
C) You can't know unless you can know the coat color of the dark squirrel's parents.
D) The trait is only an adaptation if it gives the squirrels an advantage in their habitat.

Question 8

When a population of organisms is evolving, what can you be sure is happening?

A) It's improving.
B) It's stable (no change).
C) It's getting bigger.
D) It's changing.

Question 9

What process could result from the natural selection explained by Darwin in his book The Origin of Species?

Question 10

In order for the theory of common descent and the theory of natural selection to both be supported, what can we infer about the genetic material for all life?

A) It must change very rarely.
B) It must vary spontaneously and randomly.
C) It must be transferable between adults.
D) It must be transferable between different species.

Question 11

Which group is able to evolve?

A) individual cats in a home
B) a population of asexually reproducing bacteria
C) a rose bush
D) an HIV virus that has infected a patient

Question 12

What traits increase fitness in a particular environment?

Question 13

How is tuberculosis transmitted?

A) by sexual contact
B) by contaminated food
C) by sneezes
D) by infected blood products

Question 14

If you wanted to see natural selection working in a population of mosquitoes in response to pesticide, how much pesticide should you use?

A) enough to kill most but not all the mosquitoes
B) enough to kill all the mosquitoes
C) just enough so that the mosquitoes will be exposed but not enough to kill any of them
D) enough to kill the weakest 1% of the mosquitoes

Question 15

What causes the disease tuberculosis?

A) a particular type of virus
B) a particular type of bacteria
C) exposure to polluted air
D) genetics

Question 16

A city was intensively sprayed with DDT to control houseflies. The number of houseflies was immediately greatly reduced. Each year thereafter, the city was sprayed again, but the flies gradually increased in numbers until 10 years later, when they were almost as abundant as they were when the control program began. Which explanation applies to this situation?

A) Flies from other areas moved in and replaced the ones killed by DDT.
B) The few flies that were affected by DDT but survived developed antibodies to DDT, which they passed on to their descendants.
C) The DDT caused new mutations to occur in the surviving flies, resulting in resistance to DDT.
D) The DDT killed most flies. The few that were already naturally resistant survived and passed this resistance on to their offspring.

Question 17

What is evolution?

A) a rare event
B) a process that is constantly occurring at the same rate in all organisms
C) a process that occurs as a result of differences in reproductive fitness
D) a process that occurred only in the past

Question 18

Your friend was diagnosed with strep throat 2 months ago. She was treated with antibiotics for 10 days, but two weeks after treatment, the symptoms returned. She was given a different antibiotic and her symptoms improved again, initially, but then got worse. What is happening?

A) Your friend has taken antibiotics so long that she has become tolerant to them, making them ineffective.
B) Exposure to antibiotics has caused each individual bacterial cell to evolve resistance to the antibiotics.
C) Your friend was originally infected with some bacteria that were resistant to these two antibiotics and the bacteria multiplied.
D) Your friend probably doesn't have a bacterial infection. There must be some other reason for her symptoms.

Question 19

Which variation could be subject to natural selection?

A) A dog with short legs due to malnutrition is able to crawl into holes better than his littermates.
B) A tree is not infested by a ground-dwelling beetle when the homeowner cuts the lower branches.
C) A hyena is born with a spotted fur pattern that allows it to hide in the grass better than its littermates.
D) A pigeon learns that when its keeper comes near it will get fed.

Question 20

Which of the following is not part of the theory of natural selection?

A) Individuals in a population vary.
B) Some variation can be passed on to offspring.
C) Populations produce more offspring than the environment can support.
D) All species are descended from a common ancestor.

Question 21

In a population, which individuals are most likely to survive and reproduce?

A) the individuals who are best adapted to the environment
B) the largest individuals in the group
C) the individuals who can catch the most prey
D) the individuals who grow the most rapidly

Question 22

Which description applies to individuals who are well adapted for a particular environment?

A) They may or may not be equally fit in another environment.
B) They are the best fit for all other environments.
C) They are at a disadvantage in other environments.
D) They will mutate to become fit in other environments.

Question 23

You notice in the fall that the oak trees on campus change color at slightly different times, even though the environment is the same for all the trees. What is the most likely explanation?

A) Natural selection is causing some trees to change.
B) There are different alleles of the gene responsible for color change.
C) The weather changes the genes of the oak trees each year.
D) All the trees have the same genes, but each tree makes different proteins from the genes.

Question 24

A population of caterpillars feeds on the leaves of trees in a forest and is in turn food for birds that eat them off the tree leaves. Given this information, which adaptation would be most likely to evolve?

A) Caterpillars would evolve to a larger size.
B) Caterpillars would evolve to eat the bark as well as the leaves.
C) Birds would evolve to eat more types of insects.
D) Caterpillars would evolve to a color that matched the leaves they eat.

Question 25

True or false: The goal of natural selection is to make extreme traits more common.

Question 26

As natural selection acts on a trait in a population, how will the amount of variation associated with that trait in the population change?

A) Variation will decrease.
B) Variation will increase.
C) Variation will remain the same.
D) Variation will disappear altogether.

Question 27

What is an allele?

A) a gene that has been changed by natural selection
B) a trait that has been influence by artificial selection
C) a gene that hasn't changed over time
D) a particular version of a gene

Question 28

The blueberries found in a typical grocery store have several gene differences compared to wild blueberries. What has caused this difference?

A) natural selection
B) artificial selection
C) a change in the environment
D) genetic engineering

Question 29

Which example is an evolutionary adaptation?

A) immunity to a virus caused by vaccination
B) clipped ears on a dog to prevent the dog from developing ear infections
C) webbed feet on a bird
D) a grizzly bear learning to open a Dumpster

Question 30

Which step in the theory of natural selection do humans impact the most to bring about artificial selection?

A) Individuals in a population vary.
B) Some variation can be passed on to offspring.
C) Populations produce more offspring than the environment can support.
D) There is differential survival and reproduction among individuals in a population.

Question 31

True or false: Any allele that's present in a population exists because it increases fitness.

Question 32

What is the raw material for evolution?

Question 33

After four observations, Darwin made the inference that natural selection causes what process?

Question 34

What is the primary source for new, unique genes in a population?

A) mutation
B) natural selection
C) artificial selection
D) crossing over

Question 35

Which plant is the most fit?

A) a plant with deep roots
B) a plant with large leaves
C) a plant with large flowers
D) Environmental information is required to determine fitness.

Question 36

In what way is artificial selection different from natural selection?

A) There's no difference; both have caused evolution throughout the history of life on Earth.
B) Artificial selection applies to changes in domestic animals only, while natural selection applies to all other species.
C) In artificial selection, human preference is the selecting force; in natural selection, environmental conditions are the selecting force.
D) Artificial selection causes one species to change to another, while natural selection only modifies existing species.

Question 37

Artificial selection occurs when an organism's fitness is controlled by ________.

Question 38

Which factor would exert selection pressure on a population of insects?

A) a new species of bird in the area
B) a fire
C) an earthquake
D) the introduction of a population of feral cats into the area

Question 39

True or false: Any trait that is controlled by genes can be acted on by natural selection.

Question 40

A biologist has been studying two populations of trout in Montana for the last 25 years, when the two populations were established from one common population. In the southern population, the fish now have a slightly different mouth shape. But the northern population hasn't changed from the original type. The new shape works well in catching the type of prey common in the habitat of the southern population. Which is the best explanation for the gene differences in the two populations?

A) The mutation only appeared in the southern population after it was exposed to the new prey.
B) The gene that produces the variation is probably still present in a small percentage of the northern population, but since there's no advantage to having it, individuals with the variation aren't selected.
C) The gene that produces the variation used to be present in a few individuals, but since it wasn't advantageous, individuals with that variation died out.
D) The gene that produces the variation used to be common in both populations, but since it wasn't advantageous in the northern population, the variation died out.

Question 41

True or false: Once an adaptation appears, it remains in all the descendants unless the species becomes extinct.

Question 42

True or false: Natural selection occurs so an organism can become perfectly adapted to its environment.

Question 43

Drug resistance to anti-HIV drugs is a serious problem. Why does drug resistance appear so rapidly in HIV?

A) It has a high rate of mutation.
B) It's a virus.
C) It's found in the blood.
D) It's sexually transmitted.

Question 44

In 1980, only 1 to 5% of all Staphylococcus aureus isolates were MRSA strains. Now 60 to 70% of S. aureus isolates are MRSA strains. What process is the cause of this situation?

A) stabilizing selection of humans
B) directional selection of humans
C) directional selection of bacteria
D) diversifying selection of bacteria

Question 45

True or false: During a time when resources are abundant, one would not expect much evolutionary change.

Question 46

Your text describes an experiment in which low-nutrient conditions select bacteria that would kill off other bacteria. When nutrients became plentiful again, these killer bacteria became less common because they had lower fitness in this environment, but they didn't become extinct. Why would some of the killer bacteria survive in the new environment?

A) They're waiting for a future time when that trait may be useful again.
B) They have changed the killer gene to a less costly one but can regenerate the killer gene when necessary.
C) Competition must be low enough that the disadvantage of having the killer trait isn't great enough to cause extinction.
D) The killer trait is a dominant trait, so it cannot be eliminated.

Question 47

What would happen if a mutation created a new allele that decreased fitness?

A) The new allele would spread through the population and decrease the fitness of that population.
B) The new allele would decrease the fitness of the individual that possessed it, and that individual would have few or no offspring.
C) The new allele would have to change back to an allele of higher fitness so the possessor of that allele could maintain its fitness.
D) The individual with the new allele would wait for an environmental change so that its fitness would increase again.

Question 48

Why is the phrase "survival of the fittest" somewhat misleading?

A) It implies that the best possible organism will evolve.
B) It implies that organisms will always grow bigger and more complex.
C) It implies that there's random generation of variation.
D) It implies that humans are the proper end result of evolution.

Question 49

What type of selection would include the evolution of a long neck in giraffes?

A) stabilizing selection
B) directional selection
C) diversifying selection
D) disruptive selection

Question 50

Which situation is an example of diversifying selection?

A) A population of moths with white and grey forms lives in a forest containing trees with light and dark bark.
B) Because bees prefer dark blue flowers, this color gradually becomes more dominant in a population of plants with a color ranging from light blue to dark blue.
C) A population of plants develops all orange fruit instead of a mixture of yellow, red, and orange fruit, due to animals showing a preference for orange fruit.
D) Wild cat populations gradually develop spots that allow them to be camouflaged in the dark forest.

Question 51

Many variants are produced during the long course of an HIV infection. Which variant would be most fit in the environment of the human body?

A) a virus that infects liver cells
B) a virus that reproduces very slowly
C) a virus that makes fewer mistakes when replicating its RNA
D) a virus that can't be recognized by the patient's immune system

Question 52

What type of selection is shown in this figure?

A) stabilizing selection
B) directional selection
C) diversifying selection
D) disruptive selection

Question 53

Which event is the most direct (or first) result of natural selection on a population?

A) New alleles are created when confronted with a new environment.
B) Proteins lose some functions.
C) The frequency of some alleles changes in the population.
D) Members of the population start reproducing more rapidly.

Question 54

A population of birch trees is present on the side of a mountain and is preyed upon by beetles that burrow into bark. Which tree would be the most fit?

A) a tree that grows to be the tallest
B) a tree that has thicker bark
C) a tree with more active photosynthetic enzymes
D) a tree that has thick, strong roots

Question 55

True or false: It was better for humans to walk upright, so they evolved a different pelvis than their primate ancestors.

Question 56

Which adaptation is constrained by the particular ancestral structure of the organism, resulting in a jury-rigged design?

A) antibiotic resistance in bacteria
B) anatomy that allows upright posture in humans
C) the wings of bats
D) ethanol tolerance in fruit flies

Question 57

A trait that confers ________ in one environment might make an organism less able to survive and reproduce in another environment.

A) selection
B) fitness
C) adaptation
D) alleles

Question 58

How would you describe the gene changes shown in this figure?

A) No genes have changed, since all flies have a gene for alcohol processing.
B) The number of genes in the population has increased.
C) The frequency of the fast enzyme allele has decreased.
D) The frequency of the fast enzyme allele has increased.

Question 59

When a population undergoes strong selection, what is most likely to happen to it?

A) The most common type of organism is replaced with a different type.
B) Variation increases in the population.
C) New mutations will form more frequently.
D) The number of individuals in the population will rapidly increase.

Question 60

How did an understanding of genetics lead to "the modern synthesis"?

A) It showed how traits could be passed from one organism to the next.
B) It showed how many offspring a single individual was capable of producing.
C) It showed the extent of variation for many traits.
D) It showed the kind of environmental change that could cause evolution.

Question 61

In 2005, a strain of extremely drug-resistant bacteria was isolated from a man in New York City. Public health officials braced themselves for many more cases, but they never appeared. What is the most likely explanation?

A) The strain must have reverted back to a sensitive strain in order to keep infecting more people.
B) The strain may have been less fit in other ways and thus not successful in the population.
C) The strain must have become extinct.
D) The strain must have been dormant and was waiting for the right conditions to reappear.

Question 62

Why haven't humans evolved a resistance to the common cold?

A) Colds are effectively killed by antibiotics, so there's no need.
B) Cold viruses haven't been in existence long enough to exert selective pressure.
C) Colds are not serious enough to remove nonresistant variants from the population.
D) We could evolve resistance if we stopped taking so many over-the-counter medications for colds.

Question 63

Why aren't antibiotics used against the common cold?

A) Cold viruses have already evolved resistance to antibiotics.
B) Colds are caused by viruses and have never been affected by antibiotics.
C) Antibiotics are only active against infection in the blood but not the respiratory tract.
D) They're only effective if you take them within the first few hours of the infection.

Question 64

Which statement best describes the phenomenon of antibiotic resistance in bacteria?

A) For a particular antibiotic, all bacteria are either completely resistant or completely sensitive.
B) When a type of bacteria is resistant to antibiotics, it's resistant to all antibiotics.
C) Resistance is a matter of degrees; resistance can be partial or total, and resistance to each antibiotic is a separate trait.
D) Resistance to antibiotics is a trait that didn't exist before antibiotics were developed for pharmaceutical use.

Question 65

What is combination drug therapy?

A) a succession of drugs to combat an infection-as the infecting microorganism becomes resistant to one drug, the patient is put on another
B) a mixture of drugs and homeopathic medications
C) a mixture of several different kinds of drugs given simultaneously
D) one drug that has a combination of effects

Question 66

Why is combination drug therapy less likely to lead to resistance than single drug therapy?

A) In the presence of multiple drugs, the mutation rate of HIV decreases.
B) The drugs improve the immune system so that it's better able to find and remove virus particles.
C) The likelihood of one virus spontaneously mutating to be resistant to three different drugs is extremely small.
D) There are fewer side effects associated with combination drug therapy, and the appearance of resistance is directly proportional to the severity of side effects.

Question 67

Is it possible to prevent bacteria from becoming resistant to antibiotics?

A) Yes: If we give antibiotics properly, resistance will go away and not evolve again.
B) No: Bacteria need to become resistant to anything that will kill them.
C) No: However, by using antibiotics properly, we can slow the rate at which resistance appears.
D) Yes: If we stop using antibiotics, the trait will disappear.

Question 68

What is MRSA?

A) tuberculosis bacteria resistant to antibiotics
B) any bacteria resistant to antibiotics
C) antibiotics used as a last resort for resistant bacteria
D) a form of skin bacteria that's resistant to methicillin

Question 69

Based on what you know about resistance to infection, why are some people resistant to HIV?

A) They have a strong immune system that clears the virus completely.
B) They have been immunized in an experimental program.
C) They can't be infected with HIV even when exposed.
D) They never engage in risky behavior and thus can't become infected.

Question 70

Why is widespread resistance to tuberculosis (TB) not likely to evolve any time soon?

A) Only a small percentage of people who are nonresistant to the bacterium will become infected and die from TB, so the variant will stay in the population.
B) TB is highly fatal, so those who are nonresistant will die quickly.
C) Humans are no longer evolving, so the population cannot develop widespread resistance.
D) It would be too expensive to genetically engineer people to give them the resistance gene.