Question

" A trail must be inherited but may not be expressed". Justify.

Answer 1

Characters are inherited from the parents. But not all the characters are expressed. Some characters are recessive and they are suppressed by dominant genes. The traits coded by these genes are not expressed.They are suppressed.

So in F1 generation, all the offspring produced will be same as dominant individual in the parent. But they are the carriers of both dominant and recessive genes. When they are self-pollinated, then there is a probability that recessive genes may appear in the F2 individuals which are considered to be offspring.

Monohybrid inheritance
It is the inheritance of a single characteristic controlled by different alleles of the same gene.
F1 generation is the first filial generation offspring produced by crossing two parental strains. All the progeny of F1 generation were tall i.e. the traits of only one parent were visible.
F2 generation is the second filial generation offspring produced by crossing F1’s. The F2 progeny were not all tall. Instead, one quarter of them was short indicating both the traits – that of tallness and shortness were inherited in the F2 plants.

Genotypic ratio – 1:2:1, Phenotypic ratio – 3:1.

Here in the above example, among parents one parent is tall ( dominant ) and the orther is short (recessive). In F1 generation, tall gene supresses the recessive gene. In F2 generation, recessive gene is also expressed.