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Question 26

Which of the following statements is supported by the graph below?

a
The population is in Hardy-Weinberg equilibrium, as the sum of the frequency of the dominant allele and the recessive allele is always equal to 1
b
The percentage of individuals homozygous recessive for this particular trait is increasing over time
c
Selection has caused frequencies to change over time because individuals with a dominant allele survive at higher rates than individuals with recessive alleles
d
Individuals who are homozygous recessive for this particular trait have migrated into the population, causing the frequency to approach 1
Question 27
A population of rabbits in a controlled environment contains rabbits with brown fur or white fur. The allele for brown fur (B) is dominant to the allele for white fur (b). There are 100 rabbits in the population. Of the 100 rabbits, 91 of them have brown fur and 9 of them have white fur. The fur color of each genotype is shown.

image 81b5828ee084436d998a4c49d9abc415

The Hardy-Weinberg equation is shown.

image 32fddac6652c424aa5ea52664245c240



Using the Hardy-Weinberg equation, which table correctly identifies the number of individuals with each genotype?

A.
image 24851f2a1d6641b88c9a015924dcbc3c



B.


image 5b65bba5f72346d99b8e0317cd7f7efd




C.


image 9a58b62470a84031be2fd7343fb53a70




D.


image 0c64f14697334024a3ed66266358b0b1



a
A
b
B
c
C
d
D
Question 28
When penicillin was first introduced, it was effective in destroying most of the bacteria that cause gonorrhea. Today, certain varieties of this bacterium are resistant to penicillin. Which statement best explains the appearance of these resistant varieties?

a
Penicillin stimulated the bacteria to become resistant, and the resistance was passed to the offspring.
b
Penicillin killed the susceptible bacteria, and naturally resistant variations survived to reproduce.
c
Penicillin used today is not as strong as the penicillin used when it was first introduced.
d
Penicillin stimulated the production of antigens in the resistant bacteria.
Question 29
Populations of blue tufted squirrels live on both sides of the Grand Canyon. This is an example of which isolating mechanism?

Grand Canyon National Park | national park, Arizona, United States | Britannica

a
behavioral isolation
b
structural isolation
c
geographic isolation
d
temporal isolation
Question 30
A scientist maintains a healthy culture of a single species of bacteria in a container. She then introduces a new substance into the bacterial culture. Within a day, most of the bacteria died.

Which of the following best explains why some of the bacteria survived?

a
They mutated and became a different species after exposure to the substance.
b
They had a genetic variation that gave them resistance to the added substance.
c
They absorbed the substance and broke it down in their digestive systems.
d
They were exposed to the substance long enough to develop a resistance to it.

1 answer

Here are the answers to each of your questions based on the information provided:

Question 26 Correct Answer: c
Selection has caused frequencies to change over time because individuals with a dominant allele survive at higher rates than individuals with recessive alleles. (This suggests that selective pressure may favor the dominant phenotype.)

Question 27 To determine which table correctly identifies the number of individuals with each genotype, we need to apply the Hardy-Weinberg equation. We know that:

  • p = frequency of the dominant allele (B)
  • q = frequency of the recessive allele (b)

With 9 white rabbits (homozygous recessive = bb), we can calculate q² (the frequency of bb). Since there are 100 rabbits:

  • q² = 9/100 = 0.09
  • Therefore, q = square root(0.09) = 0.3 (frequency of b)
  • To find p, we use the equation p + q = 1, thus p = 1 - 0.3 = 0.7.

Now we can use the genotype frequencies:

  • Frequency of BB (homozygous dominant) = p² = (0.7)² = 0.49
  • Frequency of Bb (heterozygous) = 2pq = 2(0.7)(0.3) = 0.42
  • Frequency of bb (homozygous recessive) = q² = (0.3)² = 0.09

Calculating the number of individuals:

  • BB = 0.49 * 100 ≈ 49
  • Bb = 0.42 * 100 ≈ 42
  • bb = 0.09 * 100 ≈ 9

We are looking for a table that has the values of 49 BB, 42 Bb, and 9 bb.

Given the options A, B, C, D, I cannot directly assess which table corresponds to those numbers without seeing the tables themselves. Please cross-check the calculated values against the provided tables.

Question 28 Correct Answer: b
Penicillin killed the susceptible bacteria, and naturally resistant variations survived to reproduce. (This is an example of natural selection.)

Question 29 Correct Answer: c
geographic isolation (The Grand Canyon acts as a physical barrier that separates squirrel populations.)

Question 30 Correct Answer: b
They had a genetic variation that gave them resistance to the added substance. (This reflects the concept of natural selection where certain traits confer survival advantages.)

Let me know if you need any further explanation or help!