Question

A self-pollinating plant with orange flower and alternating leaf arrangement produces
Plant with red flowers and alternating leave - 47
Plant with orange flower and alternating leaves -103
Plant with yellow flower and alternating leaves - 51
The allele for yellow flower color is
(a) Recessive
(b) Dominant
(c) Incompletely dominant
(d) Incompletely recessive
(e) Codominant

Answer 1

Hint: In the case of homozygous condition completely dominant show one character and completely recessive show one character which leads to two types of character dominant and recessive but in the case of heterozygous condition dominant trait shows its character and recessive does not.

Complete answer:
Let us take one character as dominant and recessive
As the above question is showing the approx. the ratio of 1:2:1 means the one is showing homozygous character and 2 is showing heterozygous character.
In the case of homozygous character, the number of genotypic counts is high in yellow flowers so we consider it as dominant and red as recessive. So, the ratio is
1:2:1
RR: Rr: rr
Yellow: orange: red

In this case, it is clearly shown that in the heterozygous condition that means in the case of orange flower the dominant flower is not showing its character that why it forms by blending of dominant and recessive, which means dominant yellow flower with recessive red flower give heterozygous orange.
As dominant is unable to show its trait that why yellow cannot be considered dominant.
It is considered incomplete dominant because if we compare it with the monotypic genotypic ratio it is the same but differs in the phenotypic ratio in F2 generation that means in its appearance.
Codominance shows both of its gene character and recessive character generally show its character in the sex chromosome.
So, the correct answer is ‘Incompletely dominant’.

Note: For considering dominant and recessive character we must compare it by Mendel given phenotypic and genotypic ratio in F2 generation. According to Mendel, the dominant character expresses itself over recessive character but as per the law of segregation, some recessive character also expresses itself with the dominant character in phenotype.