I keep getting these wrong: 1. To find a gene, you have to associate a phenotype
ID: 58638 • Letter: I
Question
I keep getting these wrong:
1. To find a gene, you have to associate a phenotype with a genotype (e.g. all individuals with white flowers have a certain allele). It is MUCH harder to find which genes are involved in polygenic traits than it is to find the genes responsible for discrete traits. Why?
2. How is it possible for offspring to have different phenotypes from their parent, even when 1) self-fertilization occurs, 2) there is no crossing over, and 3) no mutation occurs?
3. When homologs synapse in prophase of meiosis I, crossing over occurs in both pairs of non-sister chromatids, but at different locations. In terms of generating genetic variation, why is this significant?
a. The alleles associated with polygenic traits are usually co-dominant.Explanation / Answer
Based on the given data,
1)
It is much harder to find which genes are involved in polygenic traits, because the alleles associated with polygenic traits are usually co-dominant. Hence, the correct option is (a).
2)
It possible for offspring to have different phenotypes, as offspring can be homozygous at genes where parents are heterozygous. Hence, the correct answer is option (D).
3)
This is significant, because in gametes, EVERY chromosome has a unique combination of paternal and maternal alleles. Hence, the correct option is (b).