Meiosis produces megaspores (haploid), which will develop into female gametophytes, which are retained in the female cone. One of the cells of each female gametophyte develops as an egg.
Are megaspores 2n?
In diploid 2n plants female meiosis (megasporogenesis) in the Megaspore Mother Cell (MMC) gives rise to four haploid (n) megaspores, of which three degenerate (Fig. … The two polar nuclei of the central cell fuse, and form a 2n nucleus.
What is megaspores and Microspores?
Microspores are land plant spores that develop into male gametophytes, whereas megaspores develop into female gametophytes. … Megaspores are structures that are part of the alternation of generations in many seedless vascular cryptogams, all gymnosperms and all angiosperms.
What ploidy are megaspores?
So, it’s ploidy is 2n. Functional megaspore is formed after MMC undergoes several meiotic divisions. It forms megaspore tetrad out of 4 megaspore tetrad 3 of them degenerate and only one remains functional which is called functional megaspore.
Why is megaspore haploid?
4. The haploid megaspore undergoes three rounds of mitotic divisions that result in eight haploid nuclei contained in seven cells: Two synergids, one egg cell, a central cell with two nuclei, and three antipodals. 5. Double fertilization results in a diploid zygote and a triploid endosperm.
How many megaspores are found in ovule?
(B) Steps of megasporogenesis. Ovule primordia arise as finger-like projections from the placenta. The megaspore mother cell undergoes meiosis and forms four megaspores. Three of the megaspores undergo cell death.
Where are megaspores produced in angiosperms?
In gymnosperms and flowering plants, the megaspore is produced inside the nucellus of the ovule. During megasporogenesis, a diploid precursor cell, the megasporocyte or megaspore mother cell, undergoes meiosis to produce initially four haploid cells (the megaspores).
How are megaspores different from microspores?
Microspores are spores that are specifically male and give rise to male gametophytes; megaspores, on the other hand, are specifically female and give rise to female gametophytes. … The fluctuation between the diploid (sporophyte) and haploid (gametophyte) life stages that occurs in plants.
Why are megaspores and microspores different sizes?
Microspore is smaller sized representing male gametophyte develop in microsporangium by the process of microsporogenesis whereas megaspore large sized representing female gametophyte develop in megasporangium by the process of megasporogenesis. …
How microspores and megaspores are formed?
The microsporangium contains microspore mother cells, which divide by meiosis to produce haploid microspores. The microspores develop into male gametophytes that are released as pollen. The megasporangium contains megaspore mother cells, which divide by meiosis to produce haploid megaspores.
What is the ploidy level of Archesporium in ovule?
Archesporium is the tissue that gives rise to spore mother cells in plants. It is considered the first generation of the sporogenous tissue. It is a diploid structure which gives rise to spore mother cells which are also diploid. These diploid spore mother cells undergo meiosis, and produce haploid spores.
Do female gametophytes produce Microspores and megaspores?
function. … sporangia; the larger spore (megaspore) gives rise to the female gametophyte, the smaller spore (microspore) to the male. … The megaspores develop into female gametophytes and the microspores into male gametophytes.
Which of the following is diploid structure?
MMC: The full form is megaspore mother cell, this is diploid cells in the plants, which undergo meiotic division and form four haploid cells called megaspores. So it is the correct answer.
Are Synergid cells diploid?
Synergids are produced by the mitotic division in the haploid megaspore of a diploid plant. So synergids of a diploid plant are haploid.
Which of the following originates from megaspores?
A megaspore mother cell is also called the megasporocyte and is a diploid cell in plants, which undergo meiosis and produces four haploid megaspores. In most plants, only one of these megaspores is functional and develops into an embryo sac or female gametophyte.
Is Synergid haploid or diploid?
Synergids are the two nuclei in the embryo sac of flowering plants that are closely associated with the oosphere or egg cells, to form the egg apparatus. They are haploid.