The Mendelian ratio of 9 colon 3 colon 3 colon 1 is found in the course of
Answer options with 5 options
A.
monohybrid crosses.
B.
dihybrid crosses.
C.
crosses of two lines, each pure but for different alleles of a trait.
D.
repeated crossing of an Upper F subscript 1 heterozygote with a pure recessive.
E.
replication.
B. dihybrid crosses.
In peas, purple flowers (Uppercase F) are dominant to white flowers (Lowercase f). A scientist crosses a homozygous purple-flowered plant (Uppercase F Uppercase F) with a white-flowered plant (Lowercase f Lowercase f).
What percentage of the offspring are expected to have white flowers?
Answer options with 5 options
A.
0%
B.
25%
C.
50%
D.
75%
E.
100%
The answer is A. 0%.
B. dihybrid crosses.
The Mendelian ratio of 9:3:3:1 is found in the course of dihybrid crosses.
To understand why, let's break down the options:
A. Monohybrid crosses involve the crossing of individuals differing in only one trait. These crosses typically result in a 3:1 ratio, where 3 individuals show the dominant trait and 1 individual shows the recessive trait. So, option A is not correct.
B. Dihybrid crosses involve the crossing of individuals differing in two traits. In this type of cross, independent assortment of alleles occurs, resulting in a 9:3:3:1 ratio. This means that 9 individuals show both dominant traits, 3 individuals show one dominant and one recessive trait, 3 individuals show the other dominant and one recessive trait, and 1 individual shows both recessive traits. So, option B is correct.
C. Crosses of two lines, each pure but for different alleles of a trait, usually result in a 1:1 ratio of phenotypes for that trait. This option does not match the 9:3:3:1 ratio, so it is not correct.
D. Repeated crossing of an F1 heterozygote with a pure recessive would lead to a 1:1 ratio, as each cross would involve one dominant and one recessive allele. This ratio does not match the 9:3:3:1 ratio, so option D is not correct.
E. Replication does not involve the crossing of individuals, so this option is not relevant and is not correct.
In conclusion, the correct answer is B. Dihybrid crosses.