All Animals with Eyes or Eyespots That Have Been Studied

question 18

Multiple Choice

All animals with eyes or eyespots that have been studied so far share a gene in common. When mutated, the gene Pax-6 causes lack of eyes in fruit flies, tiny eyes in mice, and missing irises (and other eye parts) in humans. The sequence of Pax-6 in humans and mice is identical. There are so few sequence differences with fruit fly Pax-6 that the human/mouse version can cause eye formation in eyeless fruit flies, even though vertebrates and invertebrates last shared a common ancestor more than 500 million years ago.
-Fruit fly eyes are of the compound type, which is structurally very different from the camera-type eyes of mammals. Even the camera-type eyes of molluscs, such as octopi, are structurally quite different from those of mammals. Yet, fruit flies, octopi, and mammals possess very similar versions of Pax-6. The fact that the same gene helps produce very different types of eyes is most likely due to

• A) the few differences in nucleotide sequence among the Pax-6 genes of these organisms.
• B) variations in the number of Pax-6 genes among these organisms.
• C) the independent evolution of this gene at many different times during animal evolution.
• D) differences in the control of Pax-6 expression among these organisms.

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Definitions:

Mimic

To imitate or copy someone or something's actions, speech, or mannerisms, often for learning or entertainment.

Temperament

Describes innate aspects of an individual's personality, such as emotional reactivity and intensity, often evident early in life.

Parental Responses

The ways in which parents react to and handle their children's behavior, emotions, and needs, significantly impacting their development and psychological health.

Cultural Factors

Elements within a society that influence the thoughts, behaviors, and practices of its members, including beliefs, norms, and values.