In: Biology
3a. What is the large diploid cell that begins the development of the female gametophyte in the Pine? What are the haploid cells called, and how many are produced by meiosis of this cell? What happens to the number of these cells as development continues?
3b. Describe the parts of the seed and enclosed embryo.
3c. Distinguish between soft pines and hard pines.
3a. The large diploid cell is NUCELLUS( megasporangium). Haploid cells are called archegonium. Each meiosis produces 2 or more haploid cells. Female gametophytes bear archegonia within megasporangium retained on sporophyte.
3b. The typical seed consists of : testa, micropyle, hilum, cotyledon, radicle, plumule, endosperm.
Testa - protects embryonic plant.
Micropyle- It permits the water to enter embryo before active germination.
Hilum- It is scar left by the stalk which attached the ovule to the ovary wall.
Cotyledons- this contain high quantities of starch. In other plants, this role is performed by endosperm.
Radicle- it develops into primary root.
Plumule- this is the embryonic shoot.
3c. Soft pine, have relatively soft timber, needles in bundles of five. Stalked cones with scales lacking prickles, little resin. Their wood is close- grained, with thin, nearly sapwood and vice- versa for hard pine