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131 Five new species of bacteria were discovered in Antarctic ice core samples. The nucleotide (base) sequences of rRNA subunits were determined for the new species. The table below shows the number of nucleotide differences between the species. Which of the following phylogenetic trees is most consistent with the data?

A: C)

B: A

C: B

D: D

Microbiology MCQ
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132 The biologist discovered that from 1988 to 1993, the average beak size declined to pre-1981 levels. The reversal in beak size from 1988 to 1993 was most likely related to which of the following events?

A: A loss of food supply for the finches

B: The end of the drought

C: An increase in drought conditions

D: An increase in predators consuming finches

Microbiology MCQ
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133 Which of the following best describes the mechanism behind the change in beak size in the finch population?

A: The formation of two new finch species from a single parent species.

B: A change in gene frequencies in the finch population due to selective pressure from the environmental change.

C: A new allele appearing in the finch population as a result of mutation.

D: The achievement of dynamic equilibrium in the finch population as a result of homeostasis.

Microbiology MCQ
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134 Which of the following statements might best explain the increase in average beak size in the finch population during the drought?

A: Finches with bigger beaks are better able to crack thick-walled seeds and produce more surviving offspring.

B: Finches with bigger beaks can attack and kill finches with smaller beaks.

C: Finches with bigger beaks possess more powerful flight muscles and are able to find more food.

D: Finches that crack large seeds develop larger beaks over time.

Microbiology MCQ
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135 Which of the following procedures was most likely followed to determine the change in beak size?

A: A few finches were trapped in 1981 and again in 1987, and their beak sizes were compared.

B: The beak size in fifteen finches was measured in 1987, and the beak size in the original finches was determined by estimation.

C: The beak size in a large number of finches was measured every year from 1981 to 1987.

D: Finches were captured and bred in 1981, and the beak size of the offspring was measured.

Microbiology MCQ
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136 In the context of the Hardy-Weinberg equilibrium, which of the following factors would most likely disturb the genetic equilibrium of a population?

A: Migration of individuals into the population.

B: Random mating within the population.

C: Absence of mutation within the population.

D: No natural selection occurring within the population.

Microbiology MCQ
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137 The enzyme pepsin functions optimally at a low pH. If pepsin is present in the stomach and the stomach’s pH increases significantly above its optimal range, what will likely happen to the enzyme activity?

A: The enzyme will continue to function at the same rate.

B: The enzyme will function more efficiently due to the higher pH.

C: The enzyme will denature, leading to a decrease in activity.

D: The enzyme will become inactive but can be reactivated by lowering the pH.

Microbiology MCQ
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138 The probability of obtaining a homozygous recessive individual in the offspring from a cross between two heterozygous parents is

A: 25%

B: 50%

C: 75%

D: 100%

Microbiology MCQ
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139 The organisms on the left side of the tree are more closely related to each other than to those on the right side of the tree. Which of the following statements best describes the relationships among these organisms?

A: The organisms on the left share a more recent common ancestor with each other than with those on the right.

B: The organisms on the right share a more recent common ancestor with each other than with those on the left.

C: The organisms on the left are more similar to the organisms on the right due to convergent evolution.

D: The organisms on the left have a greater genetic diversity than those on the right.

Microbiology MCQ
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140 A population of frogs in an isolated area experiences a sudden increase in genetic diversity. Which of the following is the most likely explanation for this observation?

A: Migration of individuals from neighboring populations.

B: A significant increase in the mutation rate of the population.

C: A rapid decline in the population size due to a genetic bottleneck.

D: An increase in the population size due to improved environmental conditions.

Microbiology MCQ
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