AP Biology Unit 2 Chapter 21

In 1949, Dr. Tony Allison observed a high frequency of Kenyans carrying the sickle cell allele in coastal areas and near Lake Victoria, but a lower frequency in the highlands. What did he hypothesize?

He hypothesized that there was a connection between malaria and sickle cell disease.

Which of the following statements is FALSE?

Organisms can change their DNA in order to become better adapted to their environment.

Which of the following statements is not a part of the Hardy-Weinberg principle?

The genotype frequencies in the offspring generation must add up to two.

Rabbit ear size tends to decrease as latitude increases. This is an example of __________.

a cline

Black-bellied seedcrackers have either small beaks (better for eating soft seeds) or large beaks (better for hard seeds). There are no seeds of intermediate hardness; therefore, which kind of selection acts on beak size in seedcrackers?

disruptive selection

What conclusion can you draw from these data? Drag the correct answer into each blank.

much higher than, support

The original source of all genetic variation is __________.

mutation

Which of the following are causes of evolutionary change?

mutation natural selection genetic drift gene flow

According to the video, how quickly could evolution take place, going from the simplest light-sensitive cells to a fully-functioning eye?

over the course of 400,000 generations

Which of the following evolutionary forces consistently results in adaptive changes in allele frequencies?

selection

According to the Hardy-Weinberg theorem, the frequencies of alleles in a population will remain constant if __________ is the only process that affects the gene pool.

sexual reproduction

When should a lactase supplement be taken in order to be most effective, and why?

at the same time the dairy product is consumed, so that the lactase will be in contact with the lactose

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

contribution to the gene pool of the next generation

What is the only evolutionary mechanism that consistently leads to adaptive evolution?

natural selection

True or false? The Hardy-Weinberg model makes the following assumptions: no selection at the gene in question; no genetic drift; no gene flow; no mutation; random mating.

true

How did Dr. Allison test his hypothesis that sickle cell disease was connected to malaria? Select all that apply.

-He evaluated blood samples for malaria parasites and the presence of sickle cells. -He expanded his study area beyond Kenya to the rest of East Africa to see if malaria and sickle disease were connected.

How does Dr. Allison's work provide an example of natural selection in humans? Select all that apply.

-In areas without malaria, individuals with two sickle cell alleles reproduced at lower rates than those without sickle cell disease. -In areas with malaria, individuals with one sickle cell allele reproduced at higher rates than those with no sickle cell alleles. Submit

Based on the results of the feeding experiment, what conclusions can you draw? Select all that apply. (For help interpreting the results, see the hints.)

-Roaches ate about the same amount from the dish with no hydramethylnon as they did from the control dish. -Roaches ate about the same amount from the dish with no oleic acid as they did from the control dish. -Roaches are refusing corn syrup.

Drag the labels to complete each prediction so that it supports its hypothesis. Labels may be used once, more than once, or not at all.

1. eat glucose 2. refuse glucose 3. have an intermediate amount of aversion 4. have a mix of aversion

Which of the following best describes what we can determine about the evolution of the eye?

A variety of species exist that are likely to be similar to common ancestors whose eyes evolved to different degrees over time.

In some populations, 1 in 500 people have sickle cell disease. What reason does the film give for why a potentially deadly, inherited disease is found at such high frequencies?

Individuals with one sickle cell allele are protected from malaria and do not have sickle cell disease, thus keeping the allele in the population.

How does diploidy help to preserve genetic variation?

It allows recessive alleles that may not be favored in the current environment to be preserved in the gene pool by propagation in heterozygotes.

What is true of microevolution?

It is the kind of evolution that can change the relative abundance of a particular allele in a gene pool over the course of generations.

Why is the enzyme lactase necessary to digest dairy products?

Lactase breaks down lactose into smaller molecules that can be absorbed by the cells that line the small intestine.

Drag the percentages on the left to answer the questions on the right. Percentages may be used once, more than once, or not at all.

Parents- 1. 50% 2. 50% Offspring- 3. 25% 4. 25% 5. 50%

Drag the percentages on the left to answer the questions on the right. Percentages may be used once, more than once, or not at all.

Parents- 1. 80% 2. 20% Offspring- 3. 64% 4. 4% 5. 32% Comparing p and q in parents and offspring- 6. 80% 7. 20%

Compare sickle cell disease and malaria.

Sickle cell disease and malaria are both potentially lethal diseases.

What genotype frequencies are expected under Hardy-Weinberg equilibrium for a population with allele frequencies of p = 0.8 and q = 0.2 for a particular gene?

The expected genotype frequencies are 0.64, 0.32, and 0.04 for A1A1, A1A2 , and A2A2 , respectively.

What is the frequency of the A1 allele in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals?

The frequency of the A1 allele is 0.3.

How do lactase supplements help people who are lactose intolerant?

The supplements provide the enzyme that breaks down the lactose in dairy products.

In a bell-shaped curve, the x-axis (horizontal direction) of the graph represents which of the following?

The value of a particular characteristic; characteristics of an organism can include such traits as size and color.

A giraffe and a mouse (both mammals) have the same number of vertebrae in their neck and spine. Which of the following accounts for this?

The vertebrae in their neck and spine are homologous because they share a common ancestor.

Sharks (which are fish) and dolphins (which are mammals) are both shaped like a torpedo. Which of the following accounts for this?

Their shape arose through convergent evolution, since that shape is beneficial for animals living in the ocean.

Identify each family member's genotype in this pedigree for high-altitude adaptation. If you can't tell with certainty whether an individual is homozygous dominant or heterozygous dominant, place the label "RR or Rr" in that box.

a- Rr b- Rr c- RR or Rr d- rr e- rr f- Rr g- rr h- Rr

Blue poppies native to China were grown at a plant-breeding center in California. The plants with the thickest leaves were most likely to survive and reproduce in the drier climate. After several generations, the percentage of thick-leaved plants had increased by 42%. This adaptation of the poppies to their new environment is due to __________.

directional selection

Long necks make it easier for giraffes to reach leaves high on trees, while also making them better fighters in "neck wrestling" contests. In both cases, which kind of selection appears to have made giraffes the long-necked creatures they are today?

directional selection

Which type of selection tends to increase genetic variation?

disruptive selection

True or false? Heterozygote advantage refers to the tendency for heterozygous individuals to have better fitness than homozygous individuals. This higher fitness results in less genetic variation in the population.

false

Use the following data to complete the table of fitness calculations. Convert percentage values to decimals before you do the calculations. Round absolute fitness values to the nearest whole number; round relative fitness values to one decimal place.

food containing glucose: 136, 65, 0.5 food lacking glucose: 118, 116, 1.0 hydramethlynon: 14, 92, 6.6

What situation most likely explains the occasional high frequency of certain inherited disorders among human populations established by a small population?

founder effect

Fill in the numbers of alleles for the original naïve population. Once you know the numbers for each allele, calculate the frequency of each allele (p and q) to two decimal places.

glu+/glu+: 180, 0 glu+/glu-: 7, 7 glu-/glu-: 0, 6 total: 187, 13 p= 0.94 q= 0.06

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

microevolution

Drag each statement into the appropriate bin depending on whether it applies to natural selection, genetic drift, or gene flow.

natural selection -consistently causes a population to become better adapted to its environment -a result of differential success in reproduction -cannot cause a harmful allele to become more common genetic drift -responsible for the founder effect causes allele frequencies to fluctuate randomly -responsible for the bottleneck effect gene flow -a result of the movement of fertile individuals or their gametes -can introduce new alleles into a population's gene pool

What does the wide variety of different types of animal eyes represent?

the intermediate forms that probably occurred in the common ancestors of today's animals

The data table and phylogenetic tree from Part A are shown here with the "regular" allele and "Tibetan" allele terminology in place. Use the data table, tree, and your understanding of the EPAS1 gene to determine which of the statements below are correct.

-Some Tibetans have the "regular" EPAS1 allele. -It is possible to survive at high altitudes with a "regular" EPAS1 allele. -Some Chinese have the "Tibetan" EPAS1 allele

If a person has two normal copies of the hemoglobin allele, which statements are true? Select all that apply.

-The person is homozygous at the hemoglobin locus. ---The person is susceptible to malaria

What is the frequency of the A1A2 genotype in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals?

0.4

Drag the numbers on the left to the appropriate blanks on the right to answer these questions about a hypothetical cat population. Answers can be used once, more than once, or not at all.

1. .84 2. .16 3. .36 4. .60 5. .40 6. .48 7. .16 8. .40

Drag the terms or numbers on the left to the appropriate blanks on the right to complete the sentences. Not all terms will be used.

1. To calculate the frequency of the brown allele, count the number of brown alleles and divide by the total number of alleles in this population. 2. In this beetle population, the number of brown alleles is 8. 3. In this beetle population, the total number of alleles is 20. 4. The frequency of the brown allele in this beetle population is 0.4. 5. The frequency of the green allele in this beetle population is 0.6.

Why should we not view lactose intolerance as a disease in adult humans?

Adult humans did not consume dairy products until fairly recently in our evolutionary history.

Most people are lactose intolerant as adults, but nearly everyone produces sufficient lactase as an infant. However, in some cases, genetic mutations can occur that make an infant lactose intolerant. From an evolutionary perspective -- over thousands of years -- why would lactose intolerance in infants be very rare in the population?

Lactose intolerant infants could not digest breast milk and therefore usually died, never having the chance to pass the mutation on to their children.

Predict what will happen to the frequency of the sickle cell allele in areas where malaria has been eradicated.

The sickle cell allele will decrease in frequency.

Lactose intolerance in infants is more common in the population today than it was a hundred years ago. Why?

Today there are alternatives to breast milk, such as lactose-free formula and soy milk, so lactose intolerant infants can survive.

Which of the following best describes the likely evolutionary steps that led to a complex eye like we see in humans?

a flat sheet of light-sensitive cells; light-sensitive cells in a cup; a pinhole camera without a lens; a pinhole camera with a lens

Drag the labels to their appropriate locations in the table below. Drag the pink labels onto the pink targets in the table to indicate which mechanism of evolution is at work. Then drag the blue labels onto the blue targets to indicate the effect on allele frequencies. Labels can be used once, more than once, or not at all.

a- natural selection b- white allele increase c- genetic drift d- pruple allele increase e- genetic drift f- allele frequencies change but not predictably g- natural selection h- purple allele increase i- gene flow j- white allele increase

Drag the labels to the table below to describe how allele frequencies would be affected under different conditions. Remember that p is the frequency of the CR allele, and q is the frequency of the CW allele. Labels may be used once, more than once, or not at all.

a- p will decrease q will increase b- p will increase q will decrease c- changes in p and q cannot be determined d- p will decrease q will increase

Using the fitness values you calculated in the previous part, determine which genotype would "win" (that is, survive and reproduce more than the other) if the two genotypes had to compete for resources in the kitchens described below. (Assume that the traps are hydramethylnon + corn syrup traps.)

kitchen with food out plus traps: glu-/glu- kitchen with food out without traps: glu+/glu+ clean kitchen plus traps: glu-/glu- clean kitchen without traps: a tie

The evolutionary effects of genetic drift are greatest when __________.

the population size is small

Which of the following are basic components of the Hardy-Weinberg model?

Frequencies of two alleles in a gene pool before and after many random matings

Which hypothesis do these results support?

Glucose aversion is an incompletely dominant trait.

This phylogenetic tree shows how scientists believe the Danes, Chinese, and Tibetans are related based on the analysis of many genes. Use the data about the EPAS1 alleles to add information to the tree. (Assume that there is no interbreeding between the different populations after the lineages split.) Labels can be used once or more than once.

a- allele 2 b- allele 1 c- allele 3

Women often have complications during labor while giving birth to very large babies, whereas very small babies tend to be underdeveloped. Which kind of selection is most likely at work regarding the birth weight of babies?

stabilizing selection

Suppose you observed 455 individual cockroaches in the infested apartment after 5 years of exposure to hydramethylnon + glucose bait. If the population had not evolved, how many individuals of each genotype would you expect? Round your answers to the nearest whole number. (For help getting started, see Hint 1.)

glu+/glu+: 402 glu+/glu-: 51 glu-/glu-: 2

In which country would you most likely find a higher incidence of lactase persistence?

in a Scandinavian country where people historically raised dairy cattle and made cheese

Small Aristelliger lizards have difficulty defending territories, but large lizards are more likely to be preyed upon by owls. Which kind of selection acts on the adult body size of these lizards?

stabilizing selection