Question

How did Mendel explain that it is possible that a trait is inherited but not expressed in an organism?

Answer 1

A character is expressed depending upon whether it is dominant or recessive. A trait which is inherited, if it is a dominant character, it will expressed. While a trait which is a recessive character will not be expressed.

Eg. If any sex linked disease passes on one generation to other, In female, if it is carried by both X alleles it will be dominant and shown. If carried by only X chromosome, it will be recessive and will not be expressed. 

HOPE U UNDERSTAND

Answer 2

Mendel took pea plants to show this as he cross breeded tall pea plants with dwarf pea plant and in the F1 generation all the plants were tall and tallness was the dominant trait.
In the next generation when he cross breeded the plant of F1 generation among itself then 3 among the four plants were tall and 1 among 4 was short..
And hence we can say that it is possible that a trait is inherited but not expressed in an organism.
Hope it may help you!