NUTR 431D2 Study Guide - Midterm Guide: Agnatha, Epididymis, Spermatozoon
20 Feb 2015
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[slide 30-33: the 2 major sex determination systems in vertebrates are based on a difference in sex chromosomes (genotype) between the males and females. In 1 system, the male is the heterogametic sex (ex. mammals: male = xy, female = xx) In the other system, the female is the heterogametic sex (ex. birds: male = zz, female = Zw: describe how aphids in temperate climates use both sexual and asexual modes of reproduction. Explain: aphids can be either oviparous (when they reproduce sexually) or viviparous (during parthenogenesis) In the spring/summer, aphids go through many generations of asexual reproduction (viviparous) to produce offspring that are full clones of the mother (apomictic parthenotes) Invertebrates: in response to an external cue, neurosecretory cells release allatotropins to the corpus allatum/corpus cardiacum which then releases juvenile hormone that acts on the fat body to produce vitellogenin, compare/contrast oogenesis and ovulation in birds versus insects. Leathery, pliable egg shell: birds & some reptiles.
