7. Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fin
ID: 272575 • Letter: 7
Question
7. Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails even though their closest relatives were terrestrial reptiles that had neither dorsal fins nor tails. The dorsal fins and tails of ichthyosaurs and fish are A) homologous. B) examples of convergent evolution C) adaptations to a common environment D) A, B and C are all correct E) Only two of the responses above are correct. 8. Both ancestral birds and ancestral mammals shared a common ancestor that was terrestrial. Today. penguins (which are birds) and seals (which are mammals) have forelimbs adapted for swimming. What term best describes the relationship of the bones in the forelimbs of penguins and seals, and what term best describes the flippers of penguins and seals? A) homologous; homologous C) homologous; analogous B) analogous; homologous D) analogous; analogous 9. What must be true of any organ that is described as vestigiar? A) It must be analogous to some feature in an ancestor B) It must be homologous to some feature in an ancestor C) It must be both homologous and analogous to some feature in an ancestor D) It need be neither homologous nor analogous to some feature in an ancestor 10. The upper forelimbs of humans and bats have similar skeletal structures, whereas the corresponding bones in whales have very different shapes and proportions. However, genetic data suggest that all three kinds of organisms diverged from a Which of the following is the most likely explanation? A) Humans and bats evolved by natural selection, and whales evolved by Lamarckian mechanisms. common ancestor at about the same time. C) Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy D) Genes mutate faster in whales than in humans or bats. E) breeding between these three species today would likely result in the successful birth of a ics and more than one awkward moment between this Superhero and Aquaman. 11.It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that A) island forms and mainland forms descended from common ancestors. B) common environments are inhabited by the same organisms. C) the islands were originally part of the continent. D) the island forms and mainland forms are converging. E) island forms and mainland forms have identical gene pools. 12.DNA sequences in many human genes are very similar or even identical to the sequences of ing genes in chimpanzees. The most likely explanation for this result is that ns and chimpanzees share a relatively recent common ancestor correspondi A) huma B) humans evolved from chimpanzees. C) chimpanzees evolved from humans D) convergent evolution led to the DNA similarities. E) humans and chimpanzees are not closely related.Explanation / Answer
Answer:
7: The dorsal fins and tails of ichthyosaurs and fish are examples of convergent evolution and adaptations to a common environment.
8: The term that best describes the relationship of the bones in the forelimbs of penguins and seals is homologous and analogous.
9: It must be homologous to some feature in an ancestor must be true of any organ that is described as vestigial.
10: Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy.
11: the island forms and mainland forms descended from common ancestors.
12: humans and chimpanzees share a relatively recent common ancestor.
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