Final answer:
Cross-fertilization involves the transfer of pollen from one plant to another, promoting genetic diversity, while self-fertilization occurs within the same plant, resulting in less genetic variation.
Step-by-step explanation:
The difference between cross-fertilization and self-fertilization is that in cross-fertilization, pollen from one plant fertilizes the egg of another plant, increasing genetic diversity, whereas in self-fertilization, pollen from the same plant fertilizes its own egg, which limits genetic variation.
Cross-fertilization can occur via biotic agents like insects, birds, or bats, or abiotic agents such as wind and water. Self-fertilization happens when a flower's stigma receives pollen from its own anther, often resulting in genetically identical offspring. Plants employ various mechanisms to enhance cross-fertilization and prevent self-fertilization, ensuring survival through greater genetic variation.
Notably, the famous researcher Gregor Mendel used controlled cross-pollination methods to produce hybrids in his pea plant experiments, laying the groundwork for the field of genetics.