Genotype and Phenotype Worksheet for Biology Education

Absolutely! Let’s solve this worksheet step by step and explain the concepts clearly.

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## 🔬 Key Concepts:

- Genotype: The genetic makeup (letters like AA, Aa, aa) of an organism.
- Phenotype: The physical or observable trait (like purple flowers, brown eyes).
- Homozygous (Ho): Two identical alleles (e.g., AA or aa).
- Heterozygous (He): Two different alleles (e.g., Aa).
- Dominant allele: Represented by a capital letter (e.g., P for purple). It masks the recessive trait when present.
- Recessive allele: Represented by a lowercase letter (e.g., p for white). Only expressed if no dominant allele is present (i.e., pp).

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## ✔ Problem 1: For each genotype, indicate whether it is heterozygous (He) or homozygous (Ho)

We look at whether the two alleles are the same (homozygous) or different (heterozygous).

| Genotype | Type | Reason |
|----------|----------|----------------------------|
| AA | Ho | Both alleles same |
| Bb | He | Different alleles |
| Cc | He | Different alleles |
| DD | Ho | Both alleles same |
| Ee | He | Different alleles |
| ff | Ho | Both alleles same |
| Gg | He | Different alleles |
| HH | Ho | Both alleles same |
| ii | Ho | Both alleles same |
| Jj | He | Different alleles |
| kk | Ho | Both alleles same |
| LL | Ho | Both alleles same |
| Mm | He | Different alleles |
| nn | Ho | Both alleles same |
| oo | Ho | Both alleles same |
| pp | Ho | Both alleles same |

✔ Answers:

AA Ho
Bb He
Cc He
DD Ho
Ee He
ff Ho
Gg He
HH Ho
ii Ho
Jj He
kk Ho
LL Ho
Mm He
nn Ho
oo Ho
pp Ho

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## ✔ Problem 2: For each genotype, determine what phenotype would be possible.

🌸 Purple flowers (P) are dominant to white flowers (p)

- PP → Purple (homozygous dominant)
- Pp → Purple (heterozygous — dominant trait shows)
- pp → White (homozygous recessive — only time white appears)

👁️ Brown eyes (B) are dominant to blue eyes (b)

- BB → Brown
- Bb → Brown
- bb → Blue

🐱 Bobtails in cats are recessive (t = bobtail; T = normal tail)

- TT → Normal tail (homozygous dominant)
- Tt → Normal tail (heterozygous — dominant trait hides recessive)
- tt → Bobtail (only recessive phenotype)

> 💡 Note: Since bobtail is recessive, you must have *two* recessive alleles (tt) to show the trait.

🌱 Round seeds (R) are dominant to wrinkled seeds (r)

- RR → Round
- Rr → Round
- rr → Wrinkled

✔ Answers:

Flowers:
PP → Purple
Pp → Purple
pp → White

Eyes:
BB → Brown
Bb → Brown
bb → Blue

Cat tails:
TT → Normal tail
Tt → Normal tail
tt → Bobtail

Seeds:
RR → Round
Rr → Round
rr → Wrinkled

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## ✔ Problem 3: For each phenotype, list the genotype(s)

> Remember: Use the letter of the dominant trait.

➤ Straight hair is dominant to curly.

Let’s use:
- S = straight (dominant)
- s = curly (recessive)

So:

- Straight hair → can be SS or Ss (because dominant trait shows even with one S)
- Curly hair → must be ss (only way recessive trait appears)

➤ Pointed heads are dominant to round heads.

Let’s use:
- P = pointed (dominant)
- p = round (recessive)

So:

- Pointed head → can be PP or Pp
- Round head → must be pp

✔ Answers:

Straight → SS or Ss
Curly → ss
Pointed → PP or Pp
Round → pp

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## 🎯 Final Answer Summary:

1. Homozygous (Ho) or Heterozygous (He):

AA Ho, Bb He, Cc He, DD Ho, Ee He, ff Ho, Gg He, HH Ho, ii Ho, Jj He, kk Ho, LL Ho, Mm He, nn Ho, oo Ho, pp Ho

2. Phenotypes:

- Flowers: PP=Purple, Pp=Purple, pp=White
- Eyes: BB=Brown, Bb=Brown, bb=Blue
- Cat tails: TT=Normal, Tt=Normal, tt=Bobtail
- Seeds: RR=Round, Rr=Round, rr=Wrinkled

3. Genotypes from Phenotypes:

- Straight → SS or Ss
- Curly → ss
- Pointed → PP or Pp
- Round → pp

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✔ You’ve now mastered the basics of genotype vs. phenotype and dominance/recessiveness! Great job! 🧬🌱