Final answer:
The term 'collapse heterozygous alleles' is not standard in genetics. It may refer to the segregation of heterozygous alleles during reproduction. Heterozygous individuals have two different alleles for a gene, and these can result in different phenotypic ratios when crossed.
Step-by-step explanation:
When discussing genetics, the term 'collapse heterozygous alleles' is not commonly used in scientific literature. Instead, we often talk about the inheritance of heterozygous alleles and the potential outcomes of their segregation during gamete formation. To clarify, an individual that is heterozygous for a gene has two different alleles - one dominant and one recessive (e.g., Tt, where T is the dominant allele for tallness, and t is the recessive allele for dwarfism in Mendel's pea plants).
During reproduction, the alleles segregate so that each parent contributes one allele to the offspring. In the case of Mendel's pea plants, when two heterozygous (Tt) plants are crossed, the result is a genotypic ratio of 1 TT : 2 Tt : 1 tt, which equates to a phenotypic ratio of 3 tall plants to 1 dwarf plant due to the presence of the dominant T allele. In a situation where there is a recessive lethal allele involved, the crossing of two heterozygous individuals may result in a genotypic ratio of 2:1, as the homozygous recessive offspring do not survive.