May I have an example of a Single-Cross Hybrid Punnett Square?

1. Set up a 2 by 2 Punnett square.

2. Write the alleles for parent 1 on the left side of the Punnett square. Each gamete will have one of the two alleles of the parent. In this particular cross, half of the gametes will have the dominant (S) allele, and half will have the recessive (s) allele. We will use blue and brown to keep track of the alleles of each parent.

3. Write the alleles from parent 2 above the Punnett square.
For this heterozygous parent (Ss), half of the gametes will have the dominant (S) allele, and half will have the recessive (s) allele.

4.Fill the squares for parent 1.
Fill each square with the allele from Parent 1 that lines up with the row.

5. Fill the squares for parent 2.
Fill each square with the allele from Parent 2 that lines up with the column.

     S    s
S  SS  Ss
s   Ss  ss

this set up gives you
25 % homozygous dominant (SS)
50% heterozygous (Ss)
and
25% homozygous recessive (ss)

Phenotypes that resulted from this monohybrid cross (Ss x Ss) are:
So lets say these are peas and S stood for round and s was connected to wrinkled peas
we would have 75% round and 25% wrinkled

Here is a link to a site that has an example of a single-cross hybrid Punnett Square (also known as a monohybrid cross).

http://home.roadrunner.com/~lubehawk/BioHELP!/psquseg.jpg

Hope this helps!