mastering bio ch 13

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 of the following is a true statement about Charles Darwin?

He proposed natural selection as the mechanism of evolution.

Natural selection and evolution are two terms that are sometimes confused, even by first year biology students. What is the relation between natural selection and evolution?

Natural selection is one of several mechanisms of evolution.

Why is natural selection considered to be the most important mechanism of microevolution?

Natural selection is the only mechanism that consistently leads to adaptive changes in populations.

Which of the following is a misconception regarding natural selection?

Natural selection progressively refines organisms' adaptations, eventually leading to perfection.

Compare sickle cell disease and malaria.

Sickle cell disease and malaria are both potentially lethal diseases.

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

Sickle-cell disease is a debilitating disease that results from being homozygous recessive for the "sickle-cell allele" of a hemoglobin gene. Why is the allele present and even common in many human populations?

The sickle-cell allele confers malaria resistance to heterozygotes. In some regions where malaria is common, heterozygotes have an advantage over both homozygotes, and their reproductive success maintains the recessive allele at a high frequency in the population.

What was significant to Darwin about the fauna and flora of the Galápagos Islands?

The species were similar to South American species, indicating common descent, but they had been extensively modified and were well-adapted to island life.

In natural selection, _____ determine which phenotypes are successful.

current conditions in the local environment

A large population of mice is isolated on an island. There are two varieties of the mice, brown and gray. Their fur colors closely match the gray rock outcrops and brown soils of the island. Hawks are their main predators. This situation most likely reflects the outcome of __________.

disruptive natural selection

Consider a population of birds living on an island. Suppose several individuals of the same species from a different population migrate to the island. Due to the arrivial of the new birds, the allele frequencies in the original population change.

gene flow

The evolution of populations due to chance is

genetic drift

In Europe at the time Darwin voyaged on HMS Beagle, the popularly accepted explanation of the origin of Earth's plants and animals held that the various species __________. View Available Hint(s)

had been created rapidly by a divine creator a few thousand years before

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

has more effect on the evolution of a small population.

Under some conditions, heterozygotes have greater reproductive success than homozygotes. What is this called?

heterozygote advantage

Suppose that, with regard to a particular gene with two alleles, A and a, we know that 60% of the alleles in the gene pool of a particular large population are A. We observe this population for five generations, during which we know that no mutation, selection, or migration has occurred. After this period, the frequency of the a allele is expected to be _____.

0.4 If 60% of the alleles are A, p = 0.6. Because q = 1 - p, the frequency of the a allele must be 0.4. The conditions are compatible with equilibrium, so those frequencies should be maintained.

Approximately one out of every 2,500 Caucasians in the United States is born with the recessive genetic disorder cystic fibrosis. According to the Hardy-Weinberg equilibrium equation, approximately how many people are carriers?

1 in 25 If q2 equals 1/2,500, then q equals 1/50, p equals 49/50, and 2pq equals approximately 1/25.

Which of the following lists of assumptions was part of Charles Darwin's theory of natural selection?

1. Organisms vary in heritable ways. 2. Some traits improve the survival and reproduction of individuals who possess them. 3. Populations produce more offspring than their environment can support, so individual organisms must compete for limited resources. 4. Earth and its life are very old.

In a certain group of African people, 4% are born with sickle-cell disease, an autosomal recessive disorder. Heterozygous individuals not only don't have sickle-cell disease, but also are resistant to malaria. If this group is in Hardy-Weinberg equilibrium, what percentage of the population is heterozygous and resistant to malaria?

32% The 4% born with sickle-cell disease are homozygous for the sickle hemoglobin allele, so q2 = 0.04 and q = 0.2. Because p = 1 - q, p = 0.8, and the heterozygotes would be equal to 2pq, or 0.32.

Of the scenarios below, which represents the occurrence of evolution at its smallest scale?

A pesticide spray is heavily used on a particular farm. Initially it kills 98% of the grasshoppers on contact. Over several generations, the local grasshopper population becomes resistant to the pesticide through inheritance of resistance alleles. Other nearby grasshopper populations do not change in any noticeable way.

Different finch species have beaks of different shapes and sizes. What do these beak differences tell us?

Different finch beak shapes are evidence that finch species adapted to different environments over many generations.

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

Which example below presents a misconception about how antibiotic resistance develops?

Individual bacteria and viruses become immune to antibiotics after they are exposed to them. Eventually the antibiotics are useless.

Which would be a good example of intrasexual selection?

Male elephant seals use their huge bodies to batter each other in battles for access to mates.

Genetic evidence supports which of the following explanations for the presence of 13 different finch species on the Galápagos islands?

Many years ago, a small population of a single finch species migrated to the islands and evolved into the current 13 species.

In the normal course of evolution and adaptation, what is the most likely way for wings to develop in a tetrapod (four-limbed organism)?

The forelimbs (or possibly hind limbs) will be used for the new purpose of flight. This new function will arise through many gradual steps, and there will be aspects of the wing that reflect its history and are not perfectly suited for flight.

Which best describes the fossil record?

The fossil record is the highly ordered sequence in which fossils are found in layers of sedimentary rock.

Consider a hypothetical insect population of 100 individuals. Two equally represented alleles (A and a) exist for a particular gene. Which scenario is an example of microevolution in this population?

The population is exposed to a toxin that kills individuals with the A allele. After exposure to the toxin the population has 25 surviving individuals, and 95% of them have the aa genotype.

A population of small fish lives in a lake with a sandy bottom. The major predator of these fish is a wading bird that hunts by sight. Most of the fish are light sandy brown, but about 10% are mottled. The color pattern is heritable. 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.

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

microevolution

Of the choices listed below, which contributes the most to genetic variation among individuals in most prokaryote species?

mutation

The original source of all genetic variation is __________.

mutation

Which of the following are causes of evolutionary change?

natural selection genetic drift mutation gene flow

A geneticist studied a large grass population growing in an area of erratic rainfall and found that plants with alleles for curled leaves reproduced better in dry years and plants with alleles for flat leaves reproduced better in wet years. This situation would __________.

preserve the variability in the grass population

Genetic variation in a population of animals or plants depends mainly on which of the following?

sexual reproduction

Organisms that possess homologous structures probably __________.

share a common ancestor that also had this structure

Which of the following structures would be the LEAST likely to fossilize?

skin

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.

The first tetrapods (four-legged animals) were amphibians, which evolved from a specialized group of lobed-fin fish. An unusual fossilized animal (named Tiktaalik) was recently found; this animal possessed a mixture of fish and amphibian characteristics. What is the term used to describe such an intermediate organism?

transitional form