HW #25 - AP Biology Period 4 #22 Liem Nguyen 1/4/10...

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AP Biology Period – 4 #22 Liem Nguyen 1/4/10 Homework #25 (100108): Chapter 25 (due Friday 100108) Total points: 30 for Attempt on all questions Concept Map: 10 Points Objectives Phylogenies are Based on Common Ancestries 1. Distinguish between phylogeny and systematics. phylogeny: evolutionary history of species systematics: approach to understanding diversity/relationships of organisms Phylogeny studies evolutionary process of species, but systematics is an understanding of the diversity and relationships of modern and extinct organisms. 2. Describe the process of sedimentation and the formation of fossils. Explain which portions of organisms are most likely to fossilize. sand and silt erode deposits pile/compress to form strata forms fossil record hard shells Sedimentation occurs where sand and silt are eroded from land and carried to seas and swamps where minerals settle at the bottom along with remains of organisms. Over many years, the deposits pile up and compress to form strata, which leads to forming the fossil record, which mostly just contains the fossils of hard shells and skeletons. 3. Explain why it is crucial to distinguish between homology and analogy before selecting characters to use in the reconstruction of phylogeny. homology: similarities due to similarity in ancestry analogy: similarities due to convergent evolution When reconstructing the phylogeny of a fossil, it is important to use homology. This is because the homology shows the ancestry of the fossil while analogy shows the result of convergent evolution. 4. Explain why bird and bat wings are homologous as vertebrate forelimbs but analogous as wings. structure homologous wings analogous Although a bat may have the ability to fly due to wings, the structure of the wings is homologous, but the actual wings are analogous. This is because the structure
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of the wings are more similar to the forearm of a cat rather than the wing of a bird, but since they are still alike, their similarities are analogous. 5. Define molecular systematics. Explain some of the problems that systematists may face in carrying out molecular comparisons of nucleic acids. molecular systematics: uses comparisons of DNA, RNA, and other molecules closely related: differ at one or few sites distantly related: different bases at multiple sites insertions and deletions Molecular systematics is the use of comparisons of DNA, RNA, and other molecules to infer evolutionary relationships between genes and genomes. If the two organisms are closely related, then they differ at one or few sites, but if they are distantly related, then they have different bases at many sites and even different lengths. This is the result of an accumulation of insertions and deletions.
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This note was uploaded on 11/06/2011 for the course AP BIO 101 taught by Professor Chan during the Fall '05 term at JFK.

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HW #25 - AP Biology Period 4 #22 Liem Nguyen 1/4/10...

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