A cell biologist examines a skin cell from a lizard during metaphase of mitosis and determines that 20 chromatids are present. The role of meiosis in this species is to (Check all that apply)

Question

_____  Produce 4 daughter cells that are genetically different from each other.
_____  Produce 4 daughter cells that are genetically different from the original parental cell.
_____  Reduce the number of chromosomes per cell from 10 to 5.
_____  Reduce the number of chromosomes per cell from 20 to 10.

Clarify Question
  · What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?

  Gather Content
  · What do you know about meiosis? How does it relate to the question?

  Consider Possibilities     · What other information is related to the question? Which information is most useful?

  Choose Answer
  · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?  

  Reflect on Process
  · Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

__X__  Produce 4 daughter cells that are genetically different from each other.
__X__  Produce 4 daughter cells that are genetically different from the original parental cell.
__X__  Reduce the number of chromosomes per cell from 10 to 5.
_____  Reduce the number of chromosomes per cell from 20 to 10.

Clarify Question
  · What is the key concept addressed by the question?
        o The question asks about the number of chromosomes in mitosis and meiosis.
· What type of thinking is required?
        o You are being asked to use your knowledge of mitosis and meiosis to analyze statements about the products of meiosis.
· What key words does the question contain and what do they mean?
        o 20 chromatids in metaphase of mitosis – after replication of DNA during S phase each chromosome now contains two attached sister chromatids.

  Gather Content
  · What do you know about meiosis? How does it relate to the question?
        o If there are 20 chromatids in a cell, this means the diploid cell has 10 chromosomes.
        o These will separate during meiosis to form gametes that are haploid, each containing 5 chromosomes.  

  Consider Possibilities     · What other information is related to the question? Which information is most useful?
        o The diploid cell has 10 chromosomes, so it cannot decrease from 20 to 10 chromosomes.

  Choose Answer
  · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?  
        o Due to independent assortment and crossing over these gametes will be genetically different from each other.  Because the gametes are haploid and the parental cell is diploid these cells will also be genetically different from each other.
        o Because the parental cell has 10 chromosomes, after meiosis it will be haploid with 5 chromosomes.

  Reflect on Process
  · Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked you to analyze statements about meiosis and choose which are correct. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you recall that a cell with 20 chromatids would have 10 chromosomes?  Did you understand that during meiosis these cells would drop from 10 to 5 chromosomes?  Did you realize that after meiosis the gametes would be genetically distinct from each other and from the parental diploid cell?