The dioecious condition prevents:

In which one of the following, both autogamy and geitonogamy are prevented?

The adaptation for pollination shown in the figure is of the ..... type.

Match the following contrivances from Column-$I$ with their examples in Column-$II$.

Column-$I$	Column-$II$
$i$. Protandry	$a$. Calotropis
$ii$. Prepotency	$b$. Tobacco
$iii$. Self sterility	$c$. Sunflower
$iv$. Herkogamy	$d$. Apple

Flowers preventing self-pollination is called

When the pollen grains are not transferred from anthers to the stigma in a flower due to a physical barrier or fence,or when some natural barrier exists between the androecium and gynoecium to check self-pollination,it is known as: