Final answer:
Angiosperms have developed mechanisms such as temporal separation and physical barriers to prevent self-pollination and promote cross-pollination, increasing genetic diversity.
Step-by-step explanation:
Angiosperms, or flowering plants, have developed several mechanisms to prevent self-pollination and promote cross-pollination, which leads to increased genetic diversity. One mechanism is the temporal separation of maturity between pollen and ovary. For example, in some species, the pollen matures and is shed before the stigma of the flower becomes receptive to pollination. Another mechanism is the presence of physical barriers that prevent self-pollination, such as differences in anther and stigma length in certain flowers. Additionally, some species have male and female flowers located on different parts of the plant or borne on separate plants, making self-pollination difficult.