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Unformatted text preview: Chapter Questions Chapter 18 1. Contrast the skeleton of an echinoderm with that of an arthropod.- An echinoderm has an endoskeleton; an arthropod has an exoskeleton. 2. What four features do we share with invertebrate chordates, such as lancelets?- 1) Dorsal, hollow nerve chord. 2) notochord. 3) pharyngeal slits. 4) post-anal tail. 3. List the hierarchy of clades to which mammals belong?- Chordates, craniates, vertebrates, jawed vertebrates, tetrapods, amniotes. 4. Vertebrate jaws probably evolved from the skeletal rods supporting ___?- Gills. 5. From what structure may the swim bladder of ray-finned fishes have evolved?- Simple lungs of an ancestral species. 6. How is the term amphibian misleading?- Not all amphibians lead a “double life.” Some are terrestrial, and some are aquatic. 7. What is an amniotic egg?- An egg with a shell, housing an embryo in a fluid-filled sac, the amnion. 8. List some adaptations of birds that enhance flight?- Reduced weight, endothermic with high metabolism, efficient respiratory and circulatory system, feathered wings shaped like airfoils, good eyesight. 9. What are two hallmarks of mammals?- Hair and mammary glands. 10. Why are native species often threatened by non-native species?- Non-native species may compete with or prey on (or poison) native species that did not evolve with the newcomers and thus have not been able to adapt to their presence. Chapter 8 1. In terms of the “like begets like” adage, contrast asexual with sexual reproduction.- Asexual reproduction produces genetically identical offspring that inherit all their DNA from a single offspring. The offspring of sexual reproduction show a family resemblance, but siblings vary because they inherit different combinations of genes from the two parents. 2. Starting with a fertilized egg cell, a series of five cell divisions would produce an early embryo with how many cells?- 32 cells. 3. Why is binary fission classified as asexual reproduction?- Because the genetically identical offspring inherit their DNA from a single parent. 4. When does a chromosome consist of two identical chromatids?- When the cell is preparing to divide and has duplicated its chromosomes, but before the duplicates actually separate. 5. A researcher treats cells with a chemical that prevents DNA synthesis from starting. This treatment would trap the cells in which part of the cell cycle?- G1. 6. An organism called a plasmodial slime mold is one large cytoplasmic mass with many nuclei. Explain how such a “megacell” could form. - Mitosis occurs repeatedly without cytokinesis. 7. Contrast cytokinesis is animals with cytokinesis in plants.- In animals, cytokinesis involves a cleavage furrow in which contracting microfilaments pinch the cell in two. In plants, it evolves formation of a cell plate, a fusion of vesicles that forms new membrane and walls between the cells....
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- Fall '06
- Mitosis, Ploidy