22. Evolution of Populations

In the context of populations, how do we define evolution?

Allele frequencies can be altered by __________.

In the Hardy-Weinberg equation, p² represents __________.

In a large population of bonobos, the frequency of the recessive allele is initially 0.1. There is no migration and no selection. What is the frequency of the dominant allele? Assume that there are two alleles of this gene.

In a population in Hardy-Weinberg equilibrium, 1% of the individuals in a population show the recessive trait of a certain characteristic. In this situation, what is the value of p?

In the equation for Hardy-Weinberg equilibrium, 1 represents __________.

Approximately 1 out of every 2,500 Caucasians in the United States is born with the recessive disease cystic fibrosis. According to the Hardy-Weinberg equilibrium equation, approximately what percentage of people are carriers?

In a certain group of African people, 4% are born with sickle-cell disease (homozygous recessive). If this group is in Hardy-Weinberg equilibrium, what percentage of the group has the selective advantage of being more resistant to malaria (heterozygous) than those individuals who are homozygous for normal hemoglobin or for sickle-cell disease?

Assume a population in Hardy-Weinberg equilibrium with these genotypic frequencies: AA = 0.25, Aa = 0.50, and aa = 0.25. If you remove all the homozygous dominants and allow the remaining population to reproduce (again under Hardy-Weinberg conditions), what will be the frequency of homozygous dominants in the next generation?

Which of the following sets of conditions is required for Hardy-Weinberg equilibrium?

How does natural selection fashion organisms?

Consider a gene that exists in two allelic forms in a simple Mendelian dominant/recessive pair. In a large population of randomly breeding organisms, the frequency of a recessive allele is initially 0.3. There is no migration and no selection. Humans enter this ecosystem and selectively hunt individuals showing the dominant trait. When the gene frequency is reexamined at the end of the year, __________.

What are the four nitrogenous bases found in RNA? a. cytosine, guanine, thymine, uracil (C, G, T, U) b. adenine, cytosine, guanine, thymine (A, C, G, T) c. adenine, cytosine, guanine, uracil (A, C, G, U) d. alanine, cysteine, glycine, threonine (A, C, G, T)

In what sense is the Hardy–Weinberg principle a null hypothesis?

If the nucleotide variability of a locus equals 0%, what is the gene variability and number of alleles at that locus? a. gene variability=0%; number of alleles=0 b. gene variability=0%; number of alleles=1 c. gene variability=0%; number of alleles=2 d. gene variability>0%; number of alleles=2

There are 25 individuals in population 1, all with genotype AA, and there are 40 individuals in population 2, all with genotype aa. Assume that these populations are located far from each other and that their environmental conditions are very similar. Based on the information given here, the observed genetic variation most likely resulted from a. genetic drift. b. gene flow. c.nonrandom mating. d. directional selection.

Single strands of nucleic acids are directional, meaning that there are two different ends. What functional groups define the two different ends of a strand?

A fruit fly population has a gene with two alleles, A1 and A2. Tests show that 70% of the gametes produced in the population contain the A1 allele. If the population is in Hardy-Weinberg equilibrium, what proportion of the flies carry both A1 and A2? a. 0.7 b. 0.49 c. 0.42 d. 0.21

In a population of 2500, how many babies would you expect to have cystic fibrosis, a homozygous recessive condition, if the frequency of the dominant allele is 0.9 and the population is at Hardy–Weinberg equilibrium? a. 0.9×2500=2250 b. 2×0.9×0.1×2500=450 c. 0.9×0.1×2500=225 d. 0.1x0.1x2500=25

In a population with two alleles, B and b, the allele frequency of b is 0.4. B is dominant to b. What is the frequency of individuals with the dominant phenotype if the population is in Hardy-Weinberg equilibrium? a. 0.16 b. 0.36 c. 0.48 d. 0.84

Determine what is incorrect in the following statement: Red deer mutated their genes so that they could have larger antlers to compete for mates.

Make a concept map (see BioSkills 12) that relates DNA's primary structure to its secondary structure. Your diagram should include deoxyribonucleotides, base-stacking interactions, purines, pyrimidines, phosphodiester linkages, DNA's primary structure, DNA's secondary structure, complementary base pairing, and antiparallel double helix.

In humans, albinism is caused by loss-of-function mutations in genes involved in the synthesis of melanin, the dark pigment in skin. Only people homozygous for a loss-of-function allele (genotype aa) have the albino phenotype. In Americans of northern European ancestry, albino individuals are present at a frequency of about 1 in 10,000 (or 0.0001). Assuming that genotypes are in Hardy–Weinberg equilibrium, what is the predicted frequency of Caucasians in the United States who carry a single allele for albinism?

If you hold a salty cracker in your mouth long enough, it will begin to taste sweet. What is responsible for this change in taste?

Sickle-cell disease is caused by a recessive allele. Roughly one out of every 400 African Americans (0.25%) is afflicted with sickle-cell disease. Use the Hardy-Weinberg equation to calculate the percentage of African Americans who are carriers of the sickle-cell allele. (Hint: q2 = 0.0025.)