Video Transcript
Where in the figure of the half flower shown does meiosis happen? (A) Two and four, (B) one and two, (C) two and three, (D) four and five, or (E) one and four.
This question is asking us about the location of a special type of cell division called meiosis when it occurs in the reproductive organs of flowering plants. Flowers like the one we can see here are produced by angiosperms, which is another name for flowering plants.
An interesting fact about many angiosperm flowers is that they contain both male and female reproductive organs. It’s in these organs that meiosis will occur to form male and female gametes. The female gamete in an angiosperm is the egg cell. One egg cell is usually produced in each ovule, one of which has been labeled with a four. In this particular flower, there are eight ovules. So eight egg cells might be produced, but the number of ovules varies between flowers. Ovules are located within a flower’s ovary, which has been labeled here with a five. As the egg cell is produced by meiosis and we now know that this occurs in the ovule, which has been labeled with a four, we can eliminate options (B) and (C) as neither of these contain a four.
The male gamete in an angiosperm is contained in a fine powder called pollen, which is found in the form of pollen grains. Pollen grains and the male gametes they contain are produced in the flower’s anthers, one of which has been labeled in this diagram with a two. This is where meiosis will occur in a similar way to the development of the egg cell in the ovule. These pollen grains can then land on the sticky stigma of either the same flower or a different flower. In this diagram, the stigma has been labeled with the number one. The nuclei of the male gametes within the pollen grain can then move down the style, which has been labeled in this diagram with a three. The male nuclei will eventually reach the egg cell in the ovule, where fertilization can occur.
Now we know that meiosis occurs in the anthers and the ovules of an angiosperm’s flower. So the correct answer is (A), two and four.
