Genotype and Phenotypes worksheet - Free Printable

Let’s work through each part of the worksheet step by step.

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Part 2 (First section): For each genotype, indicate whether it is heterozygous, homozygous dominant, or homozygous recessive.

We use these rules:
- Homozygous dominant: Two capital letters → AA, BB, CC, etc.
- Heterozygous: One capital and one lowercase letter → Aa, Bb, Cc, etc.
- Homozygous recessive: Two lowercase letters → aa, bb, cc, etc.

Now let’s go one by one:

Left column:
- AA → both capitals → homozygous dominant
- Bb → one capital, one lowercase → heterozygous
- Cc → one capital, one lowercase → heterozygous
- Dd → one capital, one lowercase → heterozygous

Right column:
- Ee → one capital, one lowercase → heterozygous
- ff → both lowercase → homozygous recessive
- GG → both capitals → homozygous dominant
- HH → both capitals → homozygous dominant

Second row left:
- Ii → one capital, one lowercase → heterozygous
- Jj → one capital, one lowercase → heterozygous
- kk → both lowercase → homozygous recessive
- Ll → one capital, one lowercase → heterozygous

Second row right:
- Mm → one capital, one lowercase → heterozygous
- nn → both lowercase → homozygous recessive
- OO → both capitals → homozygous dominant
- Pp → one capital, one lowercase → heterozygous

✔ All done for Part 2 first section.

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Part 2 (Second section): For each genotype below, determine the phenotype.

Remember: Dominant trait shows up if at least one dominant allele is present. Recessive trait only shows if two recessive alleles are present.

Top left: Purple flowers (P) dominant to white (p)
- PP → has dominant P → purple
- Pp → has dominant P → purple
- pp → no dominant P → white

Top right: Brown eyes (B) dominant to blue (b)
- BB → has dominant B → brown
- Bb → has dominant B → brown
- bb → no dominant B → blue

Bottom left: Round seeds (R) dominant to wrinkled (r)
- RR → has dominant R → round
- Rr → has dominant R → round
- rr → no dominant R → wrinkled

Bottom right: Bobtails are recessive (t), long tails dominant (T)
→ So TT and Tt = long tail; tt = bobtail
- TT → long tail
- Tt → long tail
- tt → bobtail

✔ All done for Part 2 second section.

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Part 3: For each phenotype, list the genotypes.

Given: Straight hair (S) dominant to curly (s)

Phenotype “straight” → can be SS or Ss (because even one S makes straight)
Phenotype “curly” → must be ss (only way to show recessive)

So:
- straight → SS, Ss
- curly → ss

Pointed heads (H) dominant to round heads (h)

Phenotype “pointed” → HH or Hh
Phenotype “round” → hh

So:
- pointed → HH, Hh
- round → hh

✔ All done for Part 3.

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Final Answer:

Part 2 (first section):
AA – homozygous dominant
Bb – heterozygous
Cc – heterozygous
Dd – heterozygous
Ee – heterozygous
ff – homozygous recessive
GG – homozygous dominant
HH – homozygous dominant
Ii – heterozygous
Jj – heterozygous
kk – homozygous recessive
Ll – heterozygous
Mm – heterozygous
nn – homozygous recessive
OO – homozygous dominant
Pp – heterozygous

Part 2 (second section):
PP – purple
Pp – purple
pp – white
BB – brown
Bb – brown
bb – blue
RR – round
Rr – round
rr – wrinkled
TT – long tail
Tt – long tail
tt – bobtail

Part 3:
Straight hair genotypes: SS, Ss
Curly hair genotype: ss
Pointed head genotypes: HH, Hh
Round head genotype: hh