Question Video: Stating the Structure That Produces the Female Gametes in Ferns Biology

The ornamental fern π‘ƒπ‘œπ‘™π‘¦π‘π‘œπ‘‘π‘–π‘’π‘š, shown in the figure, reproduces by alternation of generations. Which structure produces female gametes?


Video Transcript

The ornamental fern Polypodium, shown in the figure, reproduces by alternation of generations. Which structure produces female gametes?

This question asks us about a multicellular organism that reproduces through alternation of generations. Alternation of generations is a very interesting phenomenon whereby an individual organism alternates between two distinct forms, usually sexual and asexual, or haploid and diploid, within its own reproductive life cycle. This pattern of reproduction is often observed in plants, such as the ornamental fern Polypodium, which is shown in the image. Let’s review the life cycle of these plants to try and answer the question regarding which structure produces female gametes.

A mature fern is also called a sporophyte and is composed entirely of diploid cells, which is often represented as 2n. Remember, β€œdiploid” means that the cells contain two complete sets of chromosomes, one set from each biological parent. If you have ever turned over the leaf of a fern, you might be surprised to find little spotlike structures, which are called sori. Each of the sori contain diploid cells called spore mother cells. Spore mother cells undergo meiosis to produce haploid spores, which are stored in a structure called a sporangium.

You may recall that a haploid cell, which is often represented as n, is one that contains only one set of chromosomes, half the number of most other body cells. The haploid spores are eventually released from the sporangium, and those that land on a suitable surface can begin to grow. The spores grow into small plants called gametophytes, which are full of haploid cells. You might recognize the word β€œgamete” in gametophytes, which refers to the fact that gametophytes are responsible for the production of sex cells, both sperm cells and egg cells.

The gametophyte contains specific structures that produce each of these types of gametes. The female gamete, which is otherwise known as an egg cell, is produced in a structure called the archegonium. The male gametes, the sperm cells, are produced in a structure called the antheridium and can travel to the archegonium of the same or adjacent plants in order to fertilize an egg cell. Once fertilization has occurred, a diploid zygote is formed, which can grow and develop into a mature sporophyte able to initiate the life cycle all over again.

Now we know the answer to the question as to which structure in a fern will produce the female gametes, or egg cells. The female gametes are produced in the archegonium.

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