BIO 126 Lecture Notes - Lecture 1: Cervix, Motility, Blastocyst
21 Mar 2016
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Asexual reproduction: some single-celled organisms reproduce using mitosis, a perfect copy (clone) of the parent results, budding. Portion of parent pinches off to form complete new individual. Complete organism formed from a fragment of parent"s body. Some animals can reproduce sexually or parthenogenically. Some organisms can reproduce by either route. Hermaphroditism: simultaneous some animals have sperm and eggs. Advantageous because there isn"t usually another tapeworm very close and there isn"t very much room inside the host"s. Gi tract for the tapeworm to sexually reproduce. Earthworms and some gastropods will cross fertilize. Some platyhelminths fight it out: sequential hermaphroditism. Protogyny (female first) or protandry (male first) can change sexes in response to signal. Simple to produce many copies of an individual. More prevalent in species from stable environments with little selection pressure for genetic diversity: sexual reproduction. Allows for greater genetic variation due to genetic recombination. Gametes are formed in gonads: testes in males, ovaries in females.
