NAME___________________________ DATE___________________ HOUR___________________

BIOLOGY I – SEX LINKED TRAITS

HEREDITY - 12

DIRECTIONS – Answer the following questions. Use a Punnett square where needed.

QUESTIONS –

  1. What are autosomes?

    2.  

     

  2. What is the genotype of a human male?__________________

    3.  

  3. What is the genotype of a human female? __________________

    4.  

  4. What is a sex linked trait?

    5.  

     

     

     

     

     

     

  5. Why is it that some recessive traits appear much more often in males than in females?

    6.  

     

     

     

     

     

     

     

  6. Using (R) for red eyes and (r) for white eyes, symbolize the following:

Red eyed female__________________ Red eyed male__________________

White eyed female__________________ White eyed male__________________

PROBLEMS –

7. Complete the following cross: XRXR x XRY

 

 

 

 

 

  1. Complete the following cross: XRXR x XrY

    2.  

     

     

     

     

     

  2. Complete the following cross: XRXr x XRY

    3.  

     

     

     

     

     

  3. Complete the following cross: XrXr x XRY

    4.  

     

     

     

     

     

  4. What is the expected phenotypic ratio of this cross: Bb x Bb (B stands for brown fur, bb indicates white fur…) There is no sex linkage here, only simple dominance.

    5.  

     

     

     

     

     

  5. What is the phenotypic ratio of this cross: XBXb x XBY.

    6.  

     

     

     

     

     

     

     

  6. How does the sex linkage affect the similar crosses from problems 11 and 12?