If there are 32 sister chromatids in a normal somatic cell, how many chromosomes are there?

Question

A.  8
B.  16
C.  32
D.  64

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 sister chromatids? 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

B.  16

Clarify Question
  · What is the key concept addressed by the question?
        o The question asks about sister chromatids.
· What type of thinking is required?
        o You are being asked to apply the definition of sister chromatids to calculate the number of chromosomes in a cell.
· What key words does the question contain and what do they mean?
        o Sister chromatids - after DNA replication, each chromosome contains two sister chromatids.  

  Gather Content
  · What do you know about sister chromatids? How does it relate to the question?
        o If there are 32 sister chromatids and two per chromosome, that means that there are 16 chromosomes.
  Consider Possibilities  
  · What other information is related to the question? Which information is most useful?
        o Sine this is a normal somatic cell it is diploid.  So the diploid number of chromosomes is 16.  A cell with 8 chromosomes would be haploid.  A cell with 32 chromosomes would be tetraploid and a cell with 64 chromosomes would be octaploid.

  Choose Answer
  · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Since this is a normal somatic cell, the diploid number will be 16.  The 32 sister chromatids would consist of 16 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 apply the definition of sister chromatids to predict the number of chromosomes in a diploid cell. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you recall that there are two sister chromatids in a chromosome?  Did you think that each sister chromatid was one chromosome?