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Formation of Sexual Structure Questions

Question 1

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Answer 1

Hormones aid recognition of different mating types of one species. In all cases where studied, one mating type constitutively releases a hormone which triggers a recognition response in the second mating type, enabling connection between compatible hyphae.

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Question 2

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Different hormones are involved with each fungus, though all appear to be peptides, and molecules in related fungi appear to be similar.

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Question 3

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Answer 3

There is more variation within the Chytrids than the remaining fungi. Therefore, the answer will rely on the remaining divisions. The principle differences appear to be the responses following initiation of the sexual interaction. Following recognition, hyphae of opposite mating types of Zygomycota anastomose and form a sporangium within which forms the diploid zygospore. In Euascomycetes, the response is a crozier which contains the diploid nucleus with branching dikaryotic cells beneath. The diploid nucleus passes immediately into meiosis, with formation of the ascus containing haploid ascospores. In yeasts the process is simpler. Plasmogamy is immediately followed by karyogamy, followed by meiosis. In Basidiomycota, separation of plasmogamy and karyogamy complicates interpretation. Some fungi have basidiospore formation analogous to Euascomycetes. Formation of the haploid basidiospores, outside the basidium, follows directly from plasmogamy and karyogamy. In the remaining fungi, plasmogamy need not be followed immediately by karyogamy. Further, karyogamy need not be followed immediately by meiosis. The haploid basidiospores form externally to the basidium.

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Question 4

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Question 5

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Question 6

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Question 7

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