Name_____________________
PUNNETT SQUARES -- CROSSES INVOLVING ONE TRAIT
In a certain species of animal, black fur (B) is dominant over brown fur (b). 
Using the  Punnett square, predict the genotypes and phenotypes 
of the offspring whose parents are both Bb or have heterozygous black fur.
wpe7F.jpg (3997 bytes) Genotypes: ______ % homozygous black fur (BB)
                  ______ % heterozygous black fur (Bb)
                  ______ % homozygous brown fur (bb)

Phenotypes_______% black fur

                  ______ % brown fur

Do the same thing when one parent is homozygous black and the other is homozygous brown.
wpe80.jpg (3997 bytes)  

Genotypes: ______ % homozygous black fur (BB)
                  ______ % heterozygous black fur (Bb)
                  ______ % homozygous brown fur (bb)

Phenotypes_______% black fur

                  ______ % brown fur

Repeat this process again when one parent is heterozygous black and the other is homozygous brown.
wpe81.jpg (3997 bytes)  

Genotypes: ______ % homozygous black fur (BB)
                  ______ % heterozygous black fur (Bb)
                  ______ % homozygous brown fur (bb)

Phenotypes_______% black fur

                  ______ % brown fur

 


Biology IF8765 (c)Instructional Fair, Inc.

 

 

 


 
These pages authored and maintained by Marcella Dawson. Revised 01/31/99. Copyright 1995 CRPC GirlTECH. All rights reserved. . Email your comments. These pages were developed through GirlTECH '96, a teacher training and student technology council program sponsored by the Center for Research on Parallel Computation (CRPC), a National Science Foundation Science and Technology Center.