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Meiosis homework Questions ANSWER KEY 1. What is the difference between metaphase I and metaphase II? Tetrads line up at the equator in metaphase I Chromosomes line up at the equator in metaphase II 2. What is the difference between anaphase I and anaphase II? Chromosomes move to opposite poles in anaphase I Chromatids move to opposite poles in anaphase II 3. Which stage of meiosis (I or II) is most like mitosis? Explain. Meiosis II is most like mitosis since chromosomes are lined up at the equator, and chromatids move to opposite poles. 4. How are haploid cells different from diploid cells in humans? Haploid cells are cells that contain half the amount of genetic information, while diploid cells have two copies of their genetic information in cells. 5. What is a tetrad? A tetrad is where two homologous chromosomes synapse with each other (line up together) during metaphase. 6. What are homologous chromosomes? Homologous chromosomes are chromosomes that carry the same genes. They have several characteristics in common such as their length, centromere location, and banding pattern. 7. Do homologous chromosomes have the same number of genes? YES 8. Do homologous chromosomes have identical genes? Explain. YES. They are identical but they carry different forms (alleles) of the same genes. 9. What are the two key features of meiosis that contribute to genetic variations? 1. Pairing of homologous chromosomes allows for crossing over, resulting in exchange of chromosome sections between chromosomes. 2. Independent assortment of homologous maternal and paternal chromosomes during metaphase I results in gametes that have different combinations of parental chromosomes. **the way they line up at metaphase I** 10. Explain why synapsis may lead to the exchange of genetic information. Synapsis is when homologous chromosomes pair up, chromosomes are close enough for “crossing over” to occur, resulting in the exchange of genetic information. 11. How is crossing over different from independent assortment? Crossing over involves homologous chromosomes exchanging pieces of chromosomes, so individual chromosomes may contain maternal and paternal genes. Independent assortment involves combinations of maternal and paternal chromosomes that can occur in a gamete. 12. Compare the key similarities and differences between spermatogenesis and Oogenesis. Similarities: Process of creating sex cells by meiosis Differences: Oogenesis occurs in females, uneven division produces one gamete and three polar bodies (later destroyed). Spermatogensis occurs in males, even division produces four gametes 13. A muscle cell of a mouse contains 22 chromosomes. Based on this information, how many chromosomes are there in the following types of mouse cells? a. Daughter muscle cell formed from mitosis 22 chromosomes b. Egg cell 22 chromatids c. Fertilized egg cell 22 chromosomes 14. When meiosis occur in females, the cytoplasm is not divided equally among the resulting four cells. Explain why. The egg cell (ovum) that results from meiosis is larger than the other 3 polar bodies because it contains most of the nutrients and organelles within the cytoplasm. This becomes important “fuel” for future cell divisions in the event that the egg cell becomes fertilized. 15. Draw a diagram of meiosis to show how a female child is produced from the union of a sperm and an egg. Parent 1 (XY, male) Parent 2 (XX, female) ↓ ↓ Meiosis Meiosis ↓ ↓ Sperm cells (n – haploid) Egg cell (n - haploid) ↘ ↙ Fertilization (sexual reproduction: X from father, X from mother) (2n-diploid) ↓ Gamete produced (XX, female baby) (2n) ↓ Embryo ↓ Child (XX, female) 16. Fill in the blanks: A diploid cell undergoes ONE nuclear division(s) in mitosis. Mitosis produces TWO diploid cells. A diploid cell undergoes TWO nuclear division(s) in meiosis. Meiosis produces FOUR haploid daughter cells. The Difference Between Mitosis & Meiosis Cell type of parent (2n or n) Cell type of daughter cell(s) (2n or n) Number of daughter cells produced Genetic relationship of daughter cells to parent cells and to each other (identical or unique) Number of cell division Mitotic Cell Division Meiotic Cell Division 2n 2n 2n N 2 4 Identical Unique 1 2