Question

Which of the following statements regarding the Hardy-Weinberg Equation is TRUE?

Answers: It can only be used when allele and genotype frequencies remain constant across generations in a population It can only be used when allele and genotype frequencies change across generations in a population It has no assumptions It mathematically shows how recessive alleles in a population decrease over time It reveals when allele frequencies change over time in a population

Assuming Hardy-Weinberg Equilibrium, what percentage of individuals in a population are carriers of Tay-Sachs disease if p = 0.45?

Answers: 0.09% 21% 42% 49.5% 91%

Two populations are completely isolated by a mountain range, but the environments on both sides of the range are exactly the same. Which of the following microevolutionary processes explains why the allele frequencies for the two populations would be different given enough time of isolation from each other?

Answers: Genetic Drift High levels of Gene Flow Mutation Natural Selection Random Mating

If the frequency of an X-linked recessive disorder is 1 in 50 births, what is the frequency of affected males in the population?

Answers: 1 in 50 births 1 in 100 births 1 in 250 births 1 in 2,500 births 1 in 5,000 births

An evolutionary tree showing the relationships between past and present primates indicates which of the following?

Answers: A species of Australopithecus turned into Chimpanzees and Humans Common ancestors can be identified by moving to more recent times on an evolutionary tree Humans share a common ancestor with the great apes Lucy is the ancestor that gave rise to Neanderthals and Humans Orangutans are more closely related to Chimpanzees than they are to Gorillas

Which of the following most accurately defines what a gene pool is?

Answers: All of the possible genotype frequencies for a given population The change in allele frequencies over generations of time The different types of potential alleles that a population could have for a gene The frequency of all the alleles a person carries for all their genes The sum of all the potential alleles for all genes in a population

Which of the following is an accurate statement about DNA profiling?

Answers: DNA evidence never degrades, so investigators can routinely find ample quantities at crime scenes or natural disaster sites regardless of environmental conditions DNA evidence cannot be used to exonerate a suspect from a conviction Hardy and Weinberg independently developed the markers used in DNA profiling Scientists now use STRs for profiling because as shorter DNA fragments they are less likely to be destroyed When a greater number of sites in the genome are compared, the probability that 2 unrelated individuals will match increases

Answer 1

1.

Hardy-Weinberg equilibrium:

• Hardy-Weinberg equation describes: The most possible distribution of the population genotype of the population, if the frequencies of the alleles are known.
• If allele frequencies are p and q, then the genotype frequencies are p2, q2, 2pq.
• A population is considered to be in Hardy-Weinberg equilibrium when:
• In a randomly mating population, allele frequency and genotype frequency remain constant.
• Thus, under Hardy-Weinberg equilibrium:

p+ q=1

p2+2pq + q2 = 1.

Assumptions:

• Population is randomly mating.
• Population size is infinitely large.
• No natural selection.
• No mutation to create new allele.
• No migration (closed population- no immigration or emigration).
• No genetic drift.
• No genetic shift.
• No gene flow.

Answers: It can only be used when allele and genotype frequencies remain constant across generations in a population.

2.

• Tay-Sach disease has autosomal recessive inheritance.

• Given:

  P= 0.45

  If the population is under Hardy-Weinberg equilibrium:

• p+q = 1
• q= 1-0.45 = 0.55
• Heterozygous or carriers = 2pq = 0.495

• Thus, percentage of Tay Sach carriers population = 0.495 x 100 = 49.5

• Answer: 49.5%

3.

• Genetic drift - Results, when a small number of individuals from a population of a geographical region, establishes a new population in a different geographical region.
• Since environment same, natural selection does not occur.
• Answer: genetic drift

4.

• Frequency of recessive allele = 1/50
• The inheritance is X-linked.
• The male is hemizygous or receives a single X- recessive to be affected by the disease.
• Thus, affected male = 1/50 (Answer)