Worksheet: Mendel and Genetic Crosses
#### Biology: Chapter 6
#### Directions:
Answer the following questions using your notes and textbook (pages 166-197).
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Problem 1: Identify whether each genotype is heterozygous (He) or homozygous (Ho)
Key Concepts:
-
Homozygous (Ho): Both alleles are the same (e.g., AA, aa).
-
Heterozygous (He): The alleles are different (e.g., Aa).
#### Genotypes:
1.
AA: Ho (homozygous dominant)
2.
Ee: He (heterozygous)
3.
ll: Ho (homozygous recessive)
4.
Mm: He (heterozygous)
5.
Bb: He (heterozygous)
6.
ff: Ho (homozygous recessive)
7.
Jj: He (heterozygous)
8.
nn: Ho (homozygous recessive)
9.
Cc: He (heterozygous)
10.
Gg: He (heterozygous)
11.
kk: Ho (homozygous recessive)
12.
oo: Ho (homozygous recessive)
13.
DD: Ho (homozygous dominant)
14.
HH: Ho (homozygous dominant)
15.
LL: Ho (homozygous dominant)
16.
Pp: He (heterozygous)
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Problem 2: Determine the possible phenotypes for each genotype
#### Key Concepts:
-
Dominant trait: Represented by a capital letter (e.g., P for purple flowers).
-
Recessive trait: Represented by a lowercase letter (e.g., p for white flowers).
#### Phenotypes:
1.
Purple flowers are dominant to white flowers (P = purple, p = white):
-
PP: Purple (homozygous dominant)
-
Pp: Purple (heterozygous, dominant trait expressed)
-
pp: White (homozygous recessive)
2.
Bobtails in cats are recessive (T = normal tail, t = bobtail):
-
TT: Normal tail (homozygous dominant)
-
Tt: Normal tail (heterozygous, dominant trait expressed)
-
tt: Bobtail (homozygous recessive)
3.
Brown eyes are dominant to blue eyes (B = brown, b = blue):
-
BB: Brown (homozygous dominant)
-
Bb: Brown (heterozygous, dominant trait expressed)
-
bb: Blue (homozygous recessive)
4.
Round seeds are dominant to wrinkled seeds (R = round, r = wrinkled):
-
RR: Round (homozygous dominant)
-
Rr: Round (heterozygous, dominant trait expressed)
-
rr: Wrinkled (homozygous recessive)
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Problem 3: List the genotypes for each phenotype
#### Key Concepts:
- For a dominant trait, the genotype can be either homozygous dominant or heterozygous.
- For a recessive trait, the genotype must be homozygous recessive.
#### Genotypes:
1.
Straight hair is dominant to curly (S = straight, s = curly):
- Straight: SS, Ss
- Curly: ss
2.
Pointed heads are dominant to round heads (P = pointed, p = round):
- Pointed: PP, Pp
- Round: pp
3.
Long tails are dominant over short tails (L = long, l = short):
- Long tail: LL, Ll
- Short tail: ll
4.
Long hair is dominant over short hair (H = long, h = short):
- Long hair: HH, Hh
- Short hair: hh
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Final Answers:
#### Problem 1:
1. AA: Ho
2. Ee: He
3. ll: Ho
4. Mm: He
5. Bb: He
6. ff: Ho
7. Jj: He
8. nn: Ho
9. Cc: He
10. Gg: He
11. kk: Ho
12. oo: Ho
13. DD: Ho
14. HH: Ho
15. LL: Ho
16. Pp: He
#### Problem 2:
1.
Purple flowers:
- PP: Purple
- Pp: Purple
- pp: White
2.
Bobtails in cats:
- TT: Normal tail
- Tt: Normal tail
- tt: Bobtail
3.
Brown eyes:
- BB: Brown
- Bb: Brown
- bb: Blue
4.
Round seeds:
- RR: Round
- Rr: Round
- rr: Wrinkled
#### Problem 3:
1.
Straight hair:
- SS, Ss
2.
Curly hair:
- ss
3.
Pointed heads:
- PP, Pp
4.
Round heads:
- pp
5.
Long tails:
- LL, Ll
6.
Short tails:
- ll
7.
Long hair:
- HH, Hh
8.
Short hair:
- hh
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Boxed Final Answer:
\[
\boxed{
\text{See detailed solutions above.}
}
\]
Parent Tip: Review the logic above to help your child master the concept of genetic worksheet.
