Solutions For An Introduction to Genetic Analysis Chapter 3 Problem 35P

7177-3-35P AID: 2975 | 20/03/2013

Two corn plants are taken which show different reactions to a pathogenic fungus. One plant is resistant [R] while the other is susceptible [S].

The first cross made is:

Parents:

Progeny: all exhibit susceptibility and are S

The second cross made is the reciprocal of the first cross:

Parents:

Progeny: All exhibit resistance and are R

By observing the above results it is clear that the susceptibility or resistance to this pathogenic fungus is due to maternal inheritance. The gene responsible is situated either on the chloroplast DNA (deoxyribonucleic acid) or on the mitochondrial DNA.

Since both these types of DNA are maternally inherited, the progeny differs in both the crosses.