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38 Cards in this Set
- Front
- Back
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reproductive cells of an organism
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gametes
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What are two examples of gametes?
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sperm or egg
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the union of a male and female gamete to form a zygote
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fertilization
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when a cell contains only one set of chromosomes
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haploid
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when a somatic cell contains two sets of chromosomes
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diploid
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What is one example of a diploid?
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body cell
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process that halves the number of chromosomes when forming specialized reproductive cells
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meiosis
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also known as reduction division
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meiosis
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four homalogous chromatids
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tetrad
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occurs when a portion of a chromatid on one homalogous chromosome are broken and exchanged with the corresponding chromatid portions of the other chromoligist and chromatin
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crossing over
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identical, no variation
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asexual reproduction
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introduces sexual variation
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sexual reproduction
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sex cells produced by meiosis
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gametes
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How many chromosomes do gametes have?
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1/2 half of normal chromsomes
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small, numerous, and quick-moving sex cells
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sperm
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large, stationary, fewer in number
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egg or ova
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when do sperm and egg fuse?
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fertilization
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how many haploids equal a diploid?
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two
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how many chromosomes in one haploid?
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23
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how many in one diploid?
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46
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Meiosis produces gametes that are?
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haploid
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How many times do DNA replicate in first interphase?
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once
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In males how many cells survive?
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four
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In what process do sperm form?
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spermatogenesis
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How many eggs or ovum survive?
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one
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An ovum contains much?
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cytoplasm
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the cytoplasm is used for?
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food
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How many eggs die
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three
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the three eggs that die are known as?
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polar bodies
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female sex chromosome
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XX
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male sex chromosome
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XY
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other 44 chromosomes except two sex chromosomes
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autosomes
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process of making gametes
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gametogenesis
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In the beginning mitosis reduces the chromosome number...?
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in half
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when is gametogenesis completed?
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in OO genesis and spermatogenesis
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external fertilization is limited to what type of environment?
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aquatic
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examples of hazards that can harm zygotes in external fertilization
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temperature and predators
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in what animals does a shell form around a zygote after fertilization
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reptiles and birds
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