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Cards In This Set
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Normal body cells are said to be, what?
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Diploid.
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Cells with only one chromosome set
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Haploid.
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Where are gamete mother cells found?
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Sex organs e.g. ovaries, testes, anthers.
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Why is sexual reproduction important?
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It maintains and introduces genetic variation into a population.
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What is the chromosome complement of an organism?
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A characteristic number of chromosomes present in the nucleus of each of its cells.
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What is Meiosis?
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The gamete mother cell divides in two and then the products divide again. These are called the 1st and 2nd meiotic divisions and result in the production of four haploid gametes.
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During meiosis, variation of gametes us caused by which 2 processes?
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1. Crossing Over
2. Independent/ Random assortment |
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What is "Crossing Over"?
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When homologous pairs of chromosomes pair up, touch at points called chiasmata and exchange genetic information.
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What is "Independent/Random assortment"?
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When homologous pairs of chromosomes arrange themselves randomly on the equator.
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Explain the importance of variation.
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To produce new combinations of genetic material in the species' gametes. In the long term, such variation is important because it helps a species to adapt to a changing environment.
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Comparison of Mitosis & Meiosis:
Site of Division |
Mitosis- animal; all over body, plant; meristems
Meiosis- animal; ovaries & testes, plant; ovaries & anthers |
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Comparison of Mitosis & Meiosis:
Function of cell division |
Mitosis- increase number of cells
Meiosis- production of sex cells (gametes) |
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Comparison of Mitosis & Meiosis:
Number of divisions |
Mitosis- 1
Meiosis- double division of nucleus, 2 |
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Comparison of Mitosis & Meiosis:
Number of cells formed |
Mitosis-two identical daughter cells
Meiosis- 4 |
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Comparison of Mitosis & Meiosis:
Effect on chromosome number |
Mitosis- conserved (kept the same)
Meiosis- chromosome number halved |
