Question

Certain species of blind fish living in perpetual darkness in the ocean depths have evolved from ancestors that could see. Research indicates that the brain centers for vision in these fish is degenerating, whereas the brain centers controlling other senses are enlarging. What might be the MOST probable reason for the loss of vision in these fish?

A. exposure to mutagens that caused the loss of vision

B. progressive selection of genetic variants in the population leading to blindness as an evolutionary adaptation

C. infection by cave-dwelling microorganisms that has led to degeneration of the eyes

D. extreme high pressure at the ocean depths causing a deterioration of vision

Male birds of paradise have evolved to possess a brilliant display of plumage. The male shows off his plumage to woo a female. Which of the following statements about this trait is true?

1. The colorful feathers in the male are a result of progressive sexual selection.

2. The female has a large part to play in the evolution of the male’s colorful plumage.

3. The colorful plumage functions as a survival advantage in its environment.

A. I only

B. II only

C. I and III

D. I and II

Darwin’s finches, which inhabit the Galapagos Islands, originally migrated from mainland South America. The loss of plants producing medium-sized nuts on one island led to the evolution of finches with either small or large beaks and selected against finches with medium-sized beaks. What kind of selective pressure is in action here?

A. directional selection

B. genetic drift

C. gene flow

D. disruptive selection

Assess which of the following variants from a population would have the maximum relative fitness.

I. Variant that matures and becomes fertile early and is short-lived.

II. Variant that matures and becomes fertile early and is long-lived.

III. Variant that is robust, long-lived, and sterile.

IV. Variant that matures and becomes fertile late and is long-lived.

A. I and IV

B. III only

C. II only

D. I and II

The peppered moth, Biston betularia, occurs as light- or dark-colored variants. Prior to the Industrial Revolution, the light-colored moths were more prevalent because they could camouflage well on lichen-covered trees. With the advent of the Industrial Revolution and increasing air pollution, dark-colored moths became more prevalent. What is the type of evolutionary force at work? Why do the darker moths become more prevalent?

A. directional selection; because lighter moths were killed by the air pollution

B. directional selection; because darker moths escaped being spotted by predators

C. genetic drift; because lighter moths were killed by the air pollution

D. genetic drift; because darker moths escaped being spotted by predators

The whiptail lizard is an all-female population in which an individual lizard reproduces by cloning itself (by a process called parthenogenesis). Because of this, all surviving whiptail lizards are clones of one another. Which of the following statements is true?

I.         The absence of sexual reproduction conserves resources and allows the population to thrive better overall.

II.        The absence of sexual reproduction conserves resources but is detrimental to the long-term survival of the species.

III.      All members of the population are equally susceptible to parasites and disease.

IV.      The population can easily adapt to any environmental change.

A. I only

B. II only

C. IV only

D. II and III

A scientist attempts to maintain a population of pea plants in a “non-evolving state” by trying to simulate the conditions required for Hardy-Weinberg equilibrium. He places the plants in a contained area under controlled conditions (no factors limiting) and makes certain that all crosses conducted are completely random. Which conditions for Hardy-Weinberg equilibrium have NOT been met?

I. no gene flow

II.       no net mutations

III.      random mating

IV. no natural selection

A. I and II

B. II and IV

C. II only

D. IV only

Among a population of lizards inhabiting an arid habitat, the skin color is controlled by two alleles—B (brown skin color) that is dominant over b (green skin color). The green lizards comprise only 4 percent of the population whereas the brown lizards comprise the rest. Over a long period of time, increased rainfall in the area leads to transformation of the habitat, with growth of shrubs and small trees. The brown and green lizard numbers almost reverse with the green lizards approaching 81 percent of the total population. Calculate the allele frequency for the green skin color before and after the climate change occurred. Why did the brown lizard, which initially had greater relative fitness than the green lizard, reduce in number drastically?

A. 2, 9; because relative fitness is dependent on environmental conditions

B. 0.2, 0.9; because relative fitness is dependent on environmental conditions

C. 0.2, 0.9; because the green lizard population acquired new adaptations that caused them to increase in number

D. 0.4, 0.81; because the green lizard population acquired new adaptations that caused them to increase in number

The organization of bones in the human arm is similar to that in a whale’s front flippers as well as to that in the wings of a bat. Clearly, these appendages in different classes of mammals have evolved to perform different functions in their respective environments. What term BEST describes these structures?

A. homologous structures

B. analogous structures

C. vestigial structures

D. convergent evolution

The Amish community in Eastern Pennsylvania stemmed from a small closed population of around 200 individuals from Eastern Europe. Certain mutant alleles have been found at higher frequencies in the Amish relative to the general population, including a rare form of dwarfism called Ellis-Van Creveld syndrome, in which the short stature is accompanied by polydactyly. Evaluate the factors driving evolution in the Amish population. Is this form of evolution adaptive? Explain.

Answer 1

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