Question

A phenotypic ratio not obtained by Mendel was
A) 3:1
B) 1:2:1
C) 1:1:1:1
D) 9:3:3:1

Answer 1

Inheritance is the process of passing genetic information from parents to offspring and the overall process of heredity relies upon inheritance. That is why offspring are much similar to their parents

Complete step by step answer:
Gregor Mendel is known as the father of genetics because he discovered three fundamental laws of inheritance. His many works are on pea plants and conclude that genes always come in pairs and they are inherited as a definite unit one from each parent.
Monohybrid cross: Mendel took one short plant and one tall plant and crossed them. He found in an F1 generation that all plants are tall. He again crossed F1 progeny and saw that the short and tall plant produced in the ratio 3:1.
Dihybrid cross: Mendel cross wrinkled green seed and round yellow seed. He observed that in the F1 generation all seeds were round- yellow. This clearly shows that the dominant trait is round and yellow. Again he self crossed the F1 progeny and observed four different characters- wrinkled yellow seed, round yellow seed, wrinkled- green seed, and round green in the ratio 9:3:3:1.
- Classic Mendelian ratio i.e. 1:1:1:1 phenotypic ratio is the result of a test cross. In this allele of two genes categorize separately into gametes.
- Incomplete dominance: 1:2:1 phenotypic ratio is a result of incomplete dominance. It can be seen in Mirabilis Jalapa’s flower where neither of its two alleles is fully dominant over others. Incomplete dominance is discovered by Carl Correns.
Mendel selected the pea plant for his experiment speak because
- They can be easily grown.
- They can be self- pollinated and can easily be cross- pollinated.
- Plants grow throughout the year and possess different characters.
So, the correct answer is, "1:2:1".

Note:
- Gregor Mendel studied 7 characters of the pea plant.
- Codominance is different from incomplete dominance. In codominance, both the alleles are expressed therefore no trait is dominant over the other. This can be seen in pigment in plants and animals.