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Unformatted text preview: Ch. 46: Animal Reproduction 09/03/2008 22:48:00 1. Distinguish between asexual and sexual reproduction. Asexual reproduction-creation of new individuals whose genes all come from one parent without the fusion of egg and sperm; most cases, relies entirely on mitotic cell division Sexual reproduction-creation of offspring by fusion of haploid gametes to form zygote (fertilized egg) which is a diploid 2. List and describe four mechanisms of asexual reproduction. Fission: the separation of a parent into two or more individuals of approximately equal size Budding: new individuals arise from outgrowths of existing ones Fragmentation: breaking of the body into several pieces, some or all of which develop into complete adults o Must be accompanied by regeneration: regrowth of lost body parts Parthenogenesis: process in which egg develops without being fertilized 3. Discuss the conditions that may favor the occurrence of asexual reproduction. Enables animals living in isolation to produce offspring without locating mates Create numerous offspring in short amount of time Most advantageous in stable, favorable environments because it perpetuates successful genotypes precisely No courtship, less time-consuming 4. Define parthenogenesis and describe the conditions that favor its occurrence. Parthenogenesis: type of reproduction in which females produce offspring from unfertilized egg Conditions it favors in Daphnia o Switch between sexual and asexual conditions is often related to season o Asexual reproduction occurs unfavorable conditions and sexual reproduction during times of environmental stress 5. Explain how hermaphroditism may be advantageous in sessile or burrowing animals. Hermaphroditism: each individual has both male and female reproductive systems o Can fertilize themselves in some species o Each animal serves as both male and female, donating and receiving sperm o Each individual encountered is potential mate, resulting in twice as many offspring then it only one individuals eggs were fertilized 6. Compare internal and external fertilization, was well as oviparity and vivipartiy external-eggs are shed by female and fertilized by male in environment o requires environment where egg can develop without desiccation or heat stress moist environment o timing is crucial to ensure mature sperm encounter ripe eggs...
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