Here are the answers to your genetics worksheet. I have worked through each problem step-by-step to ensure they are correct.
Part 1: Questions 1–7 (Based on the first Punnett Square)
Logic Check:
The provided square shows a cross between two parents who both have the genotype
Bb.
- Top row alleles: B, b
- Side column alleles: B, b
- Inside squares: BB, Bb, Bb, bb
1.
Parents' Genotype: Looking at the letters on the outside of the square, both the top and side show one capital 'B' and one lowercase 'b'.
2.
Recessive Gene: In genetics, lowercase letters always represent recessive genes.
3.
Dominant Gene: Capital letters always represent dominant genes.
4.
Offspring Genotypes: Looking inside the four boxes, we see three distinct combinations: BB, Bb, and bb.
5.
Recessive Trait: To show a recessive trait, an offspring must have two lowercase letters (homozygous recessive). Only
bb fits this.
6.
Dominant Trait: To show a dominant trait, an offspring needs at least one capital letter.
BB and
Bb fit this.
7.
50% Chance: There are 4 boxes total.
- BB appears 1 time (25%)
- Bb appears 2 times (50%)
- bb appears 1 time (25%)
Therefore,
Bb is the one with a 50% chance.
Part 2: Questions 8–10 (Drawing Squares)
8. Cross: Rr and rr
*
Setup: One parent gives R or r. The other gives only r.
*
Square Results:
- Top-Left: R + r =
Rr
- Top-Right: R + r =
Rr
- Bottom-Left: r + r =
rr
- Bottom-Right: r + r =
rr
*
Percentages:
- RR: 0 out of 4 =
0%
- Rr: 2 out of 4 =
50%
- rr: 2 out of 4 =
50%
9. Cross: HH and hh
*
Setup: One parent gives only H. The other gives only h.
*
Square Results: Every single box will be H from the top and h from the side.
- All 4 boxes are
Hh.
*
Percentages:
- HH: 0 out of 4 =
0%
- Hh: 4 out of 4 =
100%
- hh: 0 out of 4 =
0%
10. Cross: Aa and aa
*
Setup: One parent gives A or a. The other gives only a.
*
Square Results:
- Top-Left: A + a =
Aa
- Top-Right: a + a =
aa
- Bottom-Left: A + a =
Aa
- Bottom-Right: a + a =
aa
*
Percentages:
- AA: 0 out of 4 =
0%
- Aa: 2 out of 4 =
50%
- *Note: The last line in your image says "Aa" again, but based on the pattern (AA, Aa, ...), it is asking for the homozygous recessive percentage.*
- aa: 2 out of 4 =
50%
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Final Answer:
1. Bb
2. b
3. B
4. BB, Bb, bb
5. bb
6. BB, Bb
7. Bb
8. Rr and rr
RR:
0%
Rr:
50%
rr:
50%
9. HH and hh
HH:
0%
Hh:
100%
hh:
0%
10. Aa and aa
AA:
0%
Aa:
50%
aa:
50% *(Assuming the last blank is for the 'aa' genotype)*
Parent Tip: Review the logic above to help your child master the concept of punnett square worksheet answers.
