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Questions part 2: Evolution und Mechanismen der Entwicklung (VL vom 12.12.11) Due: 11:59am on Wednesday, December 14, 2011 Note: You will receive no credit for late submissions. To learn more, read your instructor's Grading Policy Chapter 25 Question 16 Description: [[Bloom's Taxonomy: Knowledge/Comprehension ]] (a) What is true of the Cambrian explosion? Part A What is true of the Cambrian explosion? ANSWER: The Cambrian explosion marks the appearance of filter-feeding animals in the fossil record. Only the fossils of microorganisms are found in geological strata older than the Cambrian explosion. The Cambrian explosion is evidence for the instantaneous creation of life on Earth. Recent evidence supports the contention that the Cambrian explosion may not have occurred over a longer period of time than was once thought. There are no fossils in geological strata that are older than the Cambrian explosion. Chapter 25 Question 63 Description: [[Bloom's Taxonomy: Synthesis/Evaluation ]] (a) The following question refers to the description below. All animals with eyes or eyespots that have been studied so far share a gene in common. When mutated, the gene -Pax causes lack of eyes in... Part A The following question refers to the description below. 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. Settings per Student Student View Summary View Diagnostics View Print View with Answers MasteringBiology: Assignment Print View http://session.masteringbiology.com/myct/assignmentPrintView?... 1 von 8 21.12.11 09:06 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 ANSWER: differences in the control of Pax-6 expression among these organisms. the independent evolution of this gene at many different times during animal evolution. the few differences in nucleotide sequence among the Pax-6 genes of these organisms. variations in the number of Pax-6 genes among these organisms.... View Full Document

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