Directions: Answer the following questions completely.
1. If human egg cells had 46 chromosomes and human sperm cells had 46 chromosomes how many chromosomes would there be in the first cell of a human baby?
2. What chromosome number is necessary for a human baby to be normal?
3. Nature has solved the problem of cutting the number of chromosomes in half in gametes with a special kind of cell division called ____________________.
4. Meiosis occurs only in reproductive organs when sex cells are made. It is really like a double cell division. The chromosomes copy _______________, but the cells divide ________________.
5. The steps of meiosis are as follows:
1. The chromosomes copy and the cell ____________________. At this stage meiosis is very similar to ____________________.
2. The two cells formed in the first division each have ___________________ chromosomes.
3.
However, these two cells do not stay as they are, but rather they divide again.
This time the chromosomes do not double. The cells that result do not have 23 pairs of chromosomes, but rather one of each pair or ____________________ chromosomes .
6. How many sperm cells come from each cell that undergoes meiosis?
7. How many egg cells come form each cell that undergoes meiosis?
8. Can the 23 chromosomes in egg and sperm ever become paired again?
9. Explain the difference in the number of chromosomes between an egg cell and a somatic cell.
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10. How are the cells at the end of meiosis different from the cells at the
beginning of meiosis? Use the terms chromosome number, haploid and
diploid in your answer.
Directions: Fill in the circles below to indicate if the cell is haploid(n) or diploid(2n).
MEIOSIS
Directions: Answer the following questions completely.
17. During which phase(s) does crossing over occur? Why is crossing over important?
18. Compare how chromosomes line up during metaphase I versus metaphase II.
19. Why is it important that meiosis produces gametes that have only half the number of chromosomes of the parent cell?
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Directions: Answer the questions in the chart below by comparing the differences and similarities between mitosis and meiosis.
Question Mitosis Meiosis
Where does it occur?
Why does it occur?
Division results in how many new cells?
Chromosome number before division? (diploid or haploid)
Chromosome number after division? (diploid or haploid)
How many times does the cell divide?
Crossing over occurs?
When?
New cell compared to original cell?
How many times do the chromosomes copy?
In humans, how many chromosomes does the original cell have?
In humans, how many chromosomes are in the new cells?
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