Grade 11 Bio Textbook Questions?

Question

7. Describe the phenotypes & genotypeswhen 2 organisms that are heterozygous for a trait are crossed.

8. How would Mendel explain why certian phenotypes & genotypes are not always expressed in offspring?

Answer 1

7.  Let's say B=brown hair (dominant) and b=blonde hair (recessive)

Genotypes:

B b

B BB Bb

b Bb  bb

Phenotypes:

Brown hair (75% chance)

and

Blonde hair (25% chance)

8.  I'm spacing on this one right now.  It's on the tip of my tongue we talked about it today!  Ahh sorry :(

Answer 2

7. Say for example you are crossing tallness. Tall is dominant to dwarf so the cross would be:

Let T=tall and t=dwarf

Tt x Tt=1/4TT,1/2Tt and 1/4tt (this are the genotypes)

3/4 would be tall and 1/4 would be dwarf.

8. Mendel was able to decipher that some traits are never expressed because of the alteration of the 3:1 ratio.

Hope this helps..