Plants can be pollinated by
cross-pollination and self-pollination. Which of the following best
describes cross-pollination? (A) An egg cell of one plant being
fertilized by a sperm cell from the same plant. (B) An egg cell of one plant being
fertilized by a sperm cell from a different plant. (C) A pollen grain of one plant
being fertilized by the ovary of a different plant. Or (D) a pollen grain of one plant
being fertilized by the ovary of the same plant.
You may recall that sexual
reproduction in flowering plants involves pollination and then fertilization of the
male and female gametes, or sex cells. Many flowering plants are able to
produce both male gametes, sperm cells, and female gametes, egg cells.
Pollen are microscopic grains that
contain the male gametes. And they are produced in parts of
the flower called anthers. Each female gamete is contained
within a structure called an ovule. Ovules are located within a flower
part called the ovary. For a male gamete to fertilize a
female gamete, first pollination must occur. This involves pollen being
transferred from the anther, where it is made, to a female part of a flower called
the stigma. This transfer of pollen from an
anther to a stigma is called pollination.
Self-pollination occurs when pollen
grains are transferred from an anther to the stigma of the same flower, like we can
see here, or to the stigma of a different flower on the same plant. Alternatively, cross-pollination
occurs when pollen grains are transferred to the stigma of a flower on a different
plant of the same species. This means that a sperm cell will
fertilize an egg cell of a different plant, with different genetic material.
Therefore, the statement that best
describes cross-pollination is (B), an egg cell of one plant being fertilized by a
sperm cell from a different plant.