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23 Cards in this Set
- Front
- Back
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Animal Sexes |
-can be male or female -hermaphrodite = both -sexual reversal: a species starts off as one gender and then later reverses to the other |
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Animal Sexes |
-determined by sex chromosomes -mammals use XY system -y chromosome = male, lack of a Y = female -other systems: XO system (some insects like grasshoppers), ZW system (birds, butterflies moths), haplo-diploid system (bees, wasps, ants, etc) |
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Haplo-Diploid System |
-unfertilized eggs are haploid & male; have no father -fertilized eggs are diploid & female; have a father & mother |
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Animal Sexes: Environmental Factors |
-in some animals, sex is not determined by chromosomes -temperature of eggs -dominance of an individual -environmental stimuli -age of an individual (sex reversal) |
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Sexual Reproduction |
-reproduction involving the production and fusion of gametes (egg & sperm) |
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Asexual Reproduction |
-reproduction without the fusion of gametes |
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Asexual Reproduction |
-fission: parent animal separates into 2 equal animals (sea anemone) -budding: outgrowth from parent animal forms new animal (hydra) -fragmentation: fragment of animal breaks off & regenerates an entire new body (porifera) -parthenogenesis (virgin birth): egg develops without fertilization into a haploid animal (bees, wasps, ants) |
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Sexual & Asexual Reproduction |
-some reproduce both sexually & asexually -water fleas -can make 2 types of eggs; can reproduce asexually when conditions are favourable, or sexually during times of stress |
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Pros & Cons of Asexual |
-pros: rapid; enhance aquisition of succesful genotypes in stable, favourable conditions -cons: limits diversity |
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Pros & Cons of Sexual |
-pros: enhance reproductive success in stressful conditions -cons: slow, due to difficulties in finding a mate |
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Reproductive Organs |
-gonads: produce gametes -ovaries: female gonads; produce eggs through the process of oogenesis -testes: male gonads; produce sperm through the process of spermatogenesis |
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Spermatogenesis |
-in testes, stem cells called spermatongonia give rise to sperm -spermatogonia divide by mitosis to produce primary spermatocyte -primaries divide by meiosis; meiosis 1 produces 2 secondary spermatocytes; meiosis II produces 4 spermatids -spermatids grow flagella..... |
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Oogenesis |
-in ovaries, stem cells oogonia give rise to eggs -oogonia divide by mitosis to produce primary oocyte -primary begins meiosis, becomes arrested before female is born; maturation begins during puberty -ovulation: release of an egg from ovary fusion of sperm & egg = fertilization -menopause: lack of eggs & stop of ovulation |
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Menstrual Cycle |
-every 28 days -2 phases: follicular & luteal -luteal: begins w/ ovulation & involves inner lining of uterus thickening; if egg released from ovary is met & fertilized, it will implant in the endometrium -if egg does not implant, the thick lining sheds through vagina in the process of menstruation; start of the follicular phase |
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Estrous Cycle |
-females have a single estrous cycle/year or several -has 5 phases; one is the estrous -females only receptive to mating mid-cycle in the estrous stage, around the time of ovulation; "in heat" |
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Mechanisms of Fertilization |
-fertilization: union/fusion of different gametes -external fertilization -internal fertilization |
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External Fertilization |
-eggs are released into the environment, where they are fertilized outside of a body -occurs in water invertebrates, fish, amphibians |
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Internal Fertilization |
-eggs are kept within the female and sperm are delivered near by, inside the female reproductive system; fertilization occurs inside the momma's body -occurs in land invertebrates, reptiles, mammals |
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Animal Development |
-begin as a single cell zygote -zygote undergoes mitotic division through cleavage, results in a blastula -cells of blastula move through gastrulation, results in gastrula -cell layers of gastrula grow into the tissues of the fuly-formed animal; called germ cell layers |
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Embryonic Tissues |
-gastrula can have 2 or 3 germ cell layers -diploblastic: animals that develop from 2 germ cell layers -triploblastic: animals that develop from 3 germ cell layers |
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Triploblastic Animals |
-3 germ cell layers; 2 categories depending on how embryo develops -protostome: blastopore forms mouth -deuterostome: blastopore forms anus |
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Animal Development |
-for amniotes (reptiles mammals), the zygote develops into a fetus with the following: -amnion: inner membrane that contains amniotic fluid -chorion: outer membrane (in mammals, chorion sticks fingers throughout the endometrium of the mom, forming a mix of the 2 tissues: placenta) -allantois: outgrowth from the gut of the fetus -yoke sac: functions as the circulatory for the embryo until it has its own (in humans, allantois & yoke sac form the umbilical cord) |
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Animal Gestation |
-gestation: process of carrying a developing animal in the womb until birth -elephants are 1.5 yrs - longest |
