Heterozygous — Science definition
Defined in 2 courses:
- Carrying two different alleles of a gene, such as Aa; such a parent produces two kinds of gamete in equal proportions. (Life Science & Scientific Inquiry)
- Having different alleles at a diploid locus. (Life Science: Biology)
Where it is taught
- Inheritance, Probability & Punnett Squares — Genes, Cell Division & Heredity, Life Science & Scientific Inquiry, Grade 7
- Mendelian Genetics — DNA, Inheritance & Gene Expression, Life Science: Biology, Grade 10
Questions using heterozygous
Problem 1
Which genotype is heterozygous at the fictional region?
- AA
- aa
- Aa
- A alone as a full diploid genotype
Answer and explanation
Aa
Aa contains two different versions at the studied region.
Problem 2
Two heterozygous parents (Tt × Tt) are crossed. What percentage of offspring are expected to show the recessive phenotype?
Answer and explanation
25 %
The expected genotypes are 1 TT : 2 Tt : 1 tt, so one quarter — 25 percent — are tt and show the recessive phenotype.
Problem 3
In the cross Tt × tt, what percentage of offspring are expected to be heterozygous?
Answer and explanation
50 %
Half the offspring receive T from the heterozygous parent and t from the homozygous recessive parent, giving Tt.