Deck 11: An Evolving Enemy: Natural Selection

Question 1

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 1

B

Question 2

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.

Answer 2

D

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

How is tuberculosis transmitted?

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

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

In order for the theory of common descent and the theory of natural selection to both be true, 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 transferrable between adults.
D) It must be transferable between different species.

Question 7

Darwin explained in his book The Origin of Species how natural selection could result in ________.

Question 8

Your friend was diagnosed with strep throat 2 months ago. She was treated with antibiotics for 10 days, but 2 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 9

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 10

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 11

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 of the following most likely explains this?

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 12

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 13

Which of the following variations 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 14

Evolution is

A) a rare event.
B) 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 15

Which of the following 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 16

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 17

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

Question 18

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 19

Traits that increase fitness in a particular environment are called ________.

Question 20

Which of the following 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.

Question 21

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 22

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 23

Which of the following 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 24

Which of the following is an 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 25

After four observations, Darwin made the inference that natural selection causes ________.

Question 26

Which of the following steps 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 27

A primary source for new, unique genes in a population is

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

Question 28

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

Question 29

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

Question 30

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 explanation best explains 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 31

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

Question 32

As natural selection acts on a trait in a population, the amount of variation associated with that trait in the population is likely to do which of the following?

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

Question 33

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 34

Which of the following is true of 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 35

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 36

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 37

The raw material for evolution is ________.

Question 38

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

Question 39

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 40

Which of the following plants is the most fit?

A) a plant with deep roots
B) a plant with large leaves
C) a plant with large flowers
D) Fitness can't be determined without reference to the environment.

Question 41

Which of these 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 42

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 43

Human females have a lifespan of over 80 years. However, the trait of living for eight decades is somewhat of a puzzle to evolutionary biologists. Why might that be?

A) The genes responsible for long life have not been identified.
B) The lifespan of human females is slightly longer than human males.
C) Women who live to be 80 don't have better relative fitness than women who live to be 50.
D) Long life can be a burden for an individual.

Question 44

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 45

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. This is an example of

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

Question 46

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

Question 47

The phrase "survival of the fittest" is somewhat misleading because

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 48

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 wouldn't the killer bacteria die out completely 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 49

What is shown in this figure?

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

Question 50

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 51

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

Question 52

Many variants are produced during the long course of an HIV infection. Which of these variants 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 53

It is most likely that dinosaur populations became extinct because

A) their environment changed.
B) different alleles became dominant in the populations.
C) mutations became common in the populations.
D) they were not perfectly adapted to their environment.

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 of the following trees 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

The evolution of a long neck in giraffes is an example of

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

Question 56

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

A) No genes have changed, since all flies have a gene for the 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 57

Which of the following 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 58

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

Question 59

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

Question 60

Which of the following is an example of jury-rigged design, or an adaptation that is constrained by the particular ancestral structure of the organism?

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 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

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 63

Drug resistance to anti-HIV drugs is a serious problem. Which of the following facts about HIV is the most direct reason why drug resistance appears so rapidly?

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 64

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 65

Which of these statements 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 66

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 67

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 68

Which of the following is the main reason widespread resistance to tuberculosis (TB)is 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.

Question 69

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 70

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 71

Based on what you know about resistance to infection, what must be unique about people who are 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 72

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.