7th Grade Mitosis/Meiosis Unit Test Study Guide Answers
Wednesday, April 26, 2017
1. List the phases of Mitosis in order. There are 3 stages and within those stages are the 4 phases of mitosis. The three stages are Interphase, Mitosis, Cytokenesis. Within the actual Mitosis stage, there are 4 phases – PMAT – prophase, metaphase, anaphase, telophase. If asked to list in order you will list all 6 aspects of the cell cycle – interphase, prophase, metaphase, anaphase, teleophase, cytokinesis.
2. If a parent cell has 8 chromosomes, at the end of mitosis, how many chromosomes are there in each daughter cell? (Remember: Mitosis produces identical cells) Since the parent cell has 8 chromosomes, each daughter cell will have 8 chromosomes a piece as well.
3. What phase of the cell cycle mitosis, does the cell spend most of it’s time? What 3 things happen during this phase? Interphase is where the cell spends most of it’s time preparing to divide. The 3 things that occur during interphase are 1. Cell doubles in size, 2. DNA replicates, 3. Organelles (centrioles) double in number
4. Which organelle is found in an animal cell, but not a plant cell? What is this organelles job? Centrioles are found in an animal cell and not a plant cell. Centrioles assist in cell division by growing spindle fibers and moving to opposite sides of the cell. The spindle fibers attach to the centromere of the chromosome and pull the sister chromatids to opposite sides of the cell.
5. What are the purposes for mitosis? There are 3 purposes for mitosis – 1. growth 2. Repair 3. Asexual Reproduction
6. What happens to the chromosomes during metaphase? They line up in the middle of the cell. Remember: Metaphase - Middle
7. List the phases of Meiosis in order. Meiosis I -Interphase, prophase I, metaphase I, anaphase I, telophase I, cytokinesis I. Metaphase II is- prophase II, metaphase II, anaphase II, telophase II, cytokinesis II
8. What is crossing over? What phase of Meiosis does this occur?
Crossing over is when nonsister chromatids of homologous chromosomes exchange genetic information, results in a new combination of genes , because of this process, every single sperm or egg cell in your body is completely unique! Crossing over must be done with SUPER precision so that neither chromatid gains or loses a gene. Think of it like two traders meeting to exchange their goods, resulting in both leaving with a more diverse collection of wares than they had before. Crossing over occurs during prophase I of meiosis. The 46 chromosomes are duplicated (now 92 total chromosomes), just like during mitosis, but before separating to divide into two daughter cells, they take part in “gene swapping.” The chromosomes are squashed together, and some genes from one chromosome are transferred to the other chromosome, and vice versa.
9. What are 2 purposes of Meiosis? There are 2 purposes for meiosis – 1) Without meiosis, all sex cells would be diploid... meaning that they have the full number of chromosomes for the species. So, when two diploid gametes join together, they form a zygote with twice the species number of chromosomes. 2) Genetic variation – the reshuffling of genes carried by the individual members of the population.
10. If sex cells have 2 chromosomes, after fertilization, when a sperm cell and egg cell meet, how many chromosomes will the resulting cell have? If a Male gamete (sperm) has 2 chromosomes and a Female gamete (egg) has 2 chromosomes and they go through the process of fertilization, then the zygote (fertilized egg) will result in 4 total chromosomes. But because meiosis is a reduction division, it has to go through PMAT again, which result in the 4 daughter cells having 2 chromosomes a piece. (refer to Amoeba Sisters: Meiosis on Youtube to refresh your memory)
11. Where are chromosomes located in a cell?
The chromosomes are located in the nucleus of a cell
12. How are mitosis and meiosis different?
Mitosis is for growth and repair and produces identical cells and only goes through its cell cycle once. Meiosis is for sexual reproduction and genetic variation, produces half the number of chromosomes as the mother cell and goes through its cell cycle twice. (refer to your chart in your packet where we checked each category)
13. Be able to label the parts of a chromosome. See next Page