Mendel found that round ( R ) seed is dominant over wrinkled ( r ) seed, and yel
ID: 188618 • Letter: M
Question
Mendel found that round (R) seed is dominant over wrinkled (r) seed, and yellow (G) seed is dominant over green (g) seed. The following crosses were made between plants of known phenotypes but unknown genotypes:
a) Using the same symbols as defined above, list the genotypes of the parent plants in each cross.
1 round, yellow X round, yellow
2 round, yellow X round, yellow
3 round, yellow X wrinkled, green
b) Which of the above crosses is a testcross?
Explanation / Answer
If round seed ( R) is doinant over wrinkle seed (r), then both homozygous RR and heterozygous Rr will have round seed phenotype and rr will have wrinkle seed.
If yellow (G) seed is dominant over green (g) seed, then homozygous GG and heterozygous Gg both will display round seed phenotype and gg will green seed.
Thus the genotype of the parents are-
1. RRGG X RRGG
2. RrGg X RrGg or RrGg X RRGG
3. RRGG X rrgg or RrGg X rrgg
Among them 3 is a test cross. In a test cross individual with a domoínant phenotype will be crossed with recessive phenotpype individual.