In plants,the gene for cytoplasmic male sterility is generally located in which of the following?

In a cross between white-flowered parents,$F_1$ progeny was uniformly purple-flowered. The $F_2$ progeny showed a phenotypic ratio $9:7$ between purple-flowered and white-flowered plants. The above result indicates that the flower colour is controlled by

In sweet pea plants,the presence of dominant $C$ and $P$ genes is essential for the development of purple colour. The ratio of plants producing flowers of different colours in the progeny of the cross $CcPp \times Ccpp$ will be:

Lethal genes are:

In which one of the following, complementary gene interaction ratio of $9: 7$ is observed?

In poultry,the new comb colour that appears by the collaboration of two dominant genes is: