Phenotype — Science definition
Defined in 2 courses:
- The observable characteristic, which usually depends on many genes together with the environment rather than on one allele. (Life Science & Scientific Inquiry)
- A measured or observed characteristic influenced by genotype and context. (Life Science: Biology)
Where it is taught
- DNA, Genes & Chromosomes — Genes, Cell Division & Heredity, Life Science & Scientific Inquiry, Grade 7
- Mendelian Genetics — DNA, Inheritance & Gene Expression, Life Science: Biology, Grade 10
In use
What you observe — the colour, the height, the shape — is the phenotype, and the relationship between alleles and phenotype is rarely one to one.
DNA, Genes & Chromosomes
Under complete dominance, the heterozygote has the modeled dominant phenotype.
Mendelian Genetics
Questions using phenotype
Problem 1
- A blend of brown and white
- It cannot be determined
- Brown
- White
Answer and explanation
Brown
One dominant B is enough to produce the brown phenotype, so Bb is brown.
Problem 2
Answer and explanation
25 %
Bb x Bb gives BB, Bb, Bb, bb — 1 of the 4 boxes (25%) is bb, the recessive phenotype.
Problem 3
Answer and explanation
Cross with bb under the model. Any bb offspring implies the tested parent supplied b. All dominant offspring in a small sample do not prove BB because Bb can produce such a sample by chance.
Problem 4
Hints
State what the supplied observations or conditions establish, and separate that from any assumption.
Answer and explanation
No. Both produce the dominant phenotype; more genotype or family evidence is required.