Question

practice: punnett squares
label the following genotypes as heterozygous or homozygous. you can use abbreviations.

1. aa ______ 2. bb ____ 3. cc ____ 4. dd ____ 5. ee ______

based on the following genotypes, determine the phenotype.

1. green pea pods are dominant to yellow.

gg ______ gg = ____ gg = ______

1. round pea pods are dominant to wrinkled.

rr ______ rr = ____ rr = ______

1. purple pea flowers are dominant to white.

pp ______ pp = ____ pp = ______
based on the following phenotypes, determine all possible genotypes.

1. tongue rolling is dominant to not being able to tongue roll in humans.

can roll = ______ cant roll = ______

1. mid - finger hair is dominant to no mid - finger hair in humans.

finger hair = ______ no finger hair = ______
answer the questions below. you will need to complete punnett squares for each question to support your answers

1. a heterozygous round pea plant is crossed with a homozygous round pea plant. (remember round is dominant to wrinkled.) what percentage of the offspring will be homozygous round?
2. a white flowered pea plant is crossed with a heterozygous purple pea plant. (remember purple is dominant to white.) what percentage of the offspring will have white flowers?
3. a green pea pod plant, that had a yellow pea pod parent, is crossed with a yellow pea pod plant. (remember green is dominant to yellow.) what percentage of the offspring will have green pea pods?

Explanation:

Step1: Define homozygous and heterozygous

Homozygous has two identical alleles, heterozygous has two different alleles.

Step2: Categorize genotypes 1 - 5

1. AA is homozygous (two identical 'A' alleles).
2. Bb is heterozygous (different 'B' and 'b' alleles).
3. Cc is heterozygous (different 'C' and 'c' alleles).
4. dd is homozygous (two identical 'd' alleles).
5. ee is homozygous (two identical 'e' alleles).

Step3: Determine phenotypes for 6 - 8

1. GG - Green (homozygous dominant), Gg - Green (heterozygous, dominant trait shows), gg - Yellow (homozygous recessive).
2. RR - Round (homozygous dominant), Rr - Round (heterozygous, dominant trait shows), rr - Wrinkled (homozygous recessive).
3. PP - Purple (homozygous dominant), Pp - Purple (heterozygous, dominant trait shows), pp - White (homozygous recessive).

Step4: Determine genotypes for 9 - 10

1. Can roll - RR or Rr (dominant trait, could be homozygous or heterozygous dominant), Can't roll - rr (homozygous recessive).
2. Finger hair - HH or Hh (dominant trait, could be homozygous or heterozygous dominant), No finger hair - hh (homozygous recessive).

Step5: Solve question 11

Let R be round (dominant) and r be wrinkled (recessive). Heterozygous round is Rr, homozygous round is RR.
The cross is Rr x RR.
The possible genotypes of offspring are RR and Rr. Probability of homozygous round (RR) is 50%.

Step6: Solve question 12

Let P be purple (dominant) and p be white (recessive). White flower is pp, heterozygous purple is Pp.
The cross is Pp x pp.
The possible genotypes of offspring are Pp and pp. Probability of white flowers (pp) is 50%.

Step7: Solve question 13

Since the green pea - pod plant had a yellow (gg) parent, its genotype must be Gg. The yellow pea - pod plant is gg.
The cross is Gg x gg.
The possible genotypes of offspring are Gg and gg. Probability of green pea - pods (Gg) is 50%.

Answer:

1. Homozygous
2. Heterozygous
3. Heterozygous
4. Homozygous
5. Homozygous
6. Green, Green, Yellow
7. Round, Round, Wrinkled
8. Purple, Purple, White
9. RR or Rr, rr
10. HH or Hh, hh
11. 50%
12. 50%
13. 50%