1. Standard 6 Emily and Cammie

2. Describe the roles of mitotic and meiotic divisions during reproduction, growth, and repair of cells.

3. What is Mitosis? Mitosis occurs when a eukaryotic cell reproduces. It divides it’s chromosomes, which are in the nucleus, into identical sets of daughter nuclei. Mitosis always produces diploid cells, which have two sets of chromosomes.

4. Stages of Mitosis Interphase Prophase Metaphase Anaphase Telophase Cytokinesis

5. Interphase The cell doubles the chromosomes through DNA replication.

6. Prophase All chromosomes and corresponding homologous chromosomes pair to form a tetrad.

7. Metaphase All the tetrads line up and attach to the spindle fibers.

8. Anaphase The spindle fibers pull the daughter chromosomes to opposite sides of the cell.

9. Telophase and Cytokinesis The chromosomes reach the opposite sides and nuclear membranes form. The cell divides into two cells.

10. What is Meiosis? In meiosis, the cells made in mitosis go through a second division. The cell’s chromosomes, which are it’s genetic information, are divided into two sex cells (sperm and egg). Later, the sex cells can combine and create an offspring with the full amount of chromosomes.

11. Phases of Meiosis The first stage of meiosis is the same as mitosis. This stage is called meiosis I. The second stage of meiosis (meiosis II) is when reduction and division takes place.

12. The First Stage of Meiosis The stages of meiosis I and mitosis are identical. They are called: Interphase I Prophase I Metaphase I Anaphase I Telophase I Cytokinesis

13. Prophase II Prophase II and prophase I are almost identical, except prophase II has half the number of chromosomes in each cell. In this phase, spindle fibers begin to develop.

14. Metaphase II The chromosomes line up and the sister chromatids face opposite sides of the cell.

15. Anaphase II During anaphase II, the paired chromatids separate and go to the opposite sides of the cell.

16. Telophase II and Cytokinesis During telophase II and cytokinesis, each set of chromosomes has a nuclear envelope form around it, which results in four haploid cells.

17. Meiosis and Variation In meiosis, crossing over (when chromosomes exchange pieces of themselves with each other, so each cells has its own unique gene combination) and independent assortment(when chromosomes are sorted independently so that each gamete, egg or sperm, obtains one pair of chromosomes) lead to genetic variation, meaning your genetics are different from your parents.

18. Meiosis and Reproduction During sexual reproduction, two haploid sex cells (which are known as gametes) form a new organism. After fertilization occurs, a zygote, or a diploid cell (which has two sets of chromosomes) is formed. Meiosis’s role is to change a diploid cell to a haploid gamete, so the genetic information of the offspring differs from the parent’s.

19. Mitosis and Cell Repair Certain body cells are needed to be regenerated occasionally because of damage. When cells repair, for example your skin, they undergo mitosis to create more skin cells to heal the wound.

20. Mitosis and Growth Every time a single cell duplicates in mitosis it causes the organism to grow because it has more cells. Once that cell duplicates, it and it’s duplicate continue to make more identical cells, increasing the cell count.

21. QUESTION TIME!

22. Meiosis and mitosis are two different reproductive processes. What happens ONLY during meiosis? A. Crossing over occurs B. Replication of organelles C. Disappearance of the nucleolus D. Complete breakdown of the nuclear membrane Question 1

23. Answer 1 A Crossing over occurs Crossing over leads to genetic variation.

24. Question 2 Which statement is correct? A.Meiosis is a way to reproduce, but mitosis is not. B. Meiosis is a way to create diversity, but mitosis is not. C. During mitosis, chromosomes are copied, but during meiosis chromosomes double. D. During mitosis, chromosomes numbers double, but during meiosis chromosome numbers remain constant.

25. Answer 2 B Meiosis is a way to create diversity, but mitosis is not. In meiosis half the genetic content from the mom and half from the dad are given to the offspring so it produces unique characteristics, but in mitosis the cell just splits so there is no diversity.

26. Question 3 Which process requires meiosis? A.Egg production B.Bacterial fission C.Flatworm regeneration D.Vegetative propagation

27. Answer 3 A Egg production Because egg production is done sexually

28. Question 4 Which statements about cell division are CORRECT? 1.Mitosis leads to variation in species. 2.Meiosis leads to variation in a species. 3.Mitosis produces haploid cells used in reproduction. 4.Meiosis produces haploid cells used in reproduction A.Statements 1 and 3 B.Statements 1 and 4 C. Statements 2 and 3 D.Statements 2 and 4

29. Answer 4 D Statements 2 and 4 Meiosis leads to variation in a species and meiosis produces haploid cells used in reproduction. Because haploid cells are used in meiosis not mitosis

30. Question 5 Red blood cells carry oxygen to the body during respiration and typically have a lifespan of four months. What is the role of mitosis during respiration? A.Allows cells to absorb oxygen from the air B.Causes cells to release oxygen to the body C.Helps replace cells that are destroyed or damaged D.Produces molecules needed to maintain cell structures

31. Answer 5 C Helps replace cells that are destroyed or damaged It does this to maintain red blood cells.

32. Question 6 Which of the following is a true statement about asexual reproduction? A.Only one organism is needed B.A mutation needs to occur C.Meiosis is necessary D.DNA is not required

33. Answer 6 A Only one organism is needed Because in asexual reproduction, a single cell splits.

34. Question 7 Which reproductive process is MOST like the regenerative process of skin cells? A.Yeast creating buds B.Ovaries forming eggs C.Ferns producing spores D.Muscles growing in size

35. Answer 7 D Muscles growing in size The cells grow because the are duplicated.

36. Question 8 Which cell process is represented by process 1 of reproduction? A.Meiosis C. Respiration B.Mitosis D. Fertilization 2n n n n n Process 1 Process 2

37. Answer 8 B Mitosis Because it is asexually divided.

38. Question 9 Study the sequence below. Which cellular process missing from this sequence produces cells having a chromosome number 2n? 2n Skin cells undergo ? Skin cells to form Having chromosome number 2n A.Meiosis C. Respiration B.Mitosis D. Fertilization

39. Answer 9 B Mitosis Because they have the same number of chromosomes.

40. Question 10 What is the third stage of Mitosis? A.Anaphase B.Prophase C.Telophase D.Metaphase

41. Answer 10 D Metaphase Anaphase is 4 th, prophase is 2 nd, and telophase is 5 th.

42. Question 11 Which is produced by meiosis? A.4 Haploid cells B.2 Diploid cells C.2 Haploid cells D.4 Diploid cells

43. Answer 11 A Four haploid cells In the first stage of meiosis (mitosis) it makes diploid cells, but in the second stage, it makes 4 haploid cells.

44. Question 12 Fill in the blank. Crossing over and _____ lead to genetic variation. A. Duplicate Chromosomes B. Independent assortment C. Asexual reproduction D. Fertilization

45. Answer 12 B Independent assortment Because duplicate chromosomes, fertilization, and asexual reproduction cannot lead to variation.

46. Question 13 Cytokinesis occurs under this stage of mitosis. A.Telophase B.Metaphase C.Anaphase D.Interphase

47. Answer 13 A Telophase Because it is the last phase

48. Question 14 Fill in the blanks. Cell division is a process that enables organisms to _____ and ________. A.Divide and reproduce B. Reproduce and distribute C. Divide and grow D. Grow and reproduce

49. Answer 14 D Grow and reproduce Because during mitosis and meiosis, the cells grow and reproduce.

50. Question 15 What phase of Mitosis is this cell in? A. metaphase B. anaphase C. telophase D. interphase

51. Answer 15 C Telophase Because there is a cleavage furrow and the daughter chromosomes arrive at the poles.