BIS+2C+Ans+to+Study+Questions+3+S09

BIS+2C+Ans+to+Study+Questions+3+S09 - Keen & Dehesh W09 BIS...

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Keen & Dehesh W09 -1- BIS 2C Study Questions 3 Fungi and Metazoans 1. The cnidarian life cycle contains polyps, medusae, and a free-swimming larva. Explain which parts of the life cycle are made by asexual reproduction, which are made by sexual reproduction, and which engage in sexual reproduction. The stage that reproduces sexually is the medusa in Hydrozoan and Scyphozoa. The polyp reproduces sexually and asexually in Anthozoa. When a medusa reproduces sexually gametes fuse to make a free-swimming larva. This settles to become the first polyp of a new genotype. The remaining polyps are made asexually. Polyps also make medusa asexually. 2 . How many layers occur in a lichen? What is the function of each layer? There are 4 layers in a lichen: the top layer is protective, the second absorbs light, the third stores food and can swell to hold water, and the fourth is protective. 3 . Which layer is photosynthetic in a lichen? The second layer is photosynthetic. 4. What feature is shared between fungi and insect exoskeletons? Why would someone say that this feature first evolved in opisthokonts and is ancestral for all metazoans? They both have chitin in them. Fungi and metazoans are both within Opisthokonta, so it is possible that the common ancestor of fungi and metazoans had chitin, making it ancestral for both clades. 5. Biologists develop a new term, dikaryotic or N + N, for fungi. Why did the terms haploid (N) and diploid (2N) not suffice in this case? In ascomycete and basidiomycete fungi there are times when the hyphae fuse and haploid nuclei from two different mating types (genotypes) are in contact (shared cytoplasm), but the nuclei do not fuse. In this case the hyphae with both types of nuclei are N+N. It would be wrong to call the hyphae haploid, but since the nuclei have not fused, they are also not diploid. 6. Which of the following organisms belong to the group of cnidarians without a medusa stage in the life cycle? large ocean-going jellies sea anemones corals cubozoans the polyp stage of hydrozoans
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Keen & Dehesh W09 -2- 7. Bivalves are unusual molluscs because: a) they have a foot (all have this) b) they have a mantle (all have this) c) they lack a radula (all other molluscs have this) d) they have a closed circulatory system --they don't have this e) they have gills (all molluscs have gills, but bivalve gills are larger) 8 . What is the Principle of Continuity and how does a sponge use it to slow water down during food collection and to speed water up as it exits the body? This Principle says that, given an incompressible fluid and a rigid pipe, the inflow velocity times the inflow cross-sectional area = the outflow velocity times the outflow cross-sectional area. If water enters a sponge through a small pore and reaches an area with a larger cross-sectional area, it will slow down—this is where the choanocytes collect food. When water that entered
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This note was uploaded on 10/08/2009 for the course BIS 2 taught by Professor Schwartzandkeen during the Spring '09 term at UC Davis.

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BIS+2C+Ans+to+Study+Questions+3+S09 - Keen & Dehesh W09 BIS...

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