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Plant embryonic development, also plant embryogenesis, is a process that occurs after the fertilization of an ovule to produce a fully developed plant embryo. This is a pertinent stage in the plant life cycle that is followed by dormancy and germination . [ 1 ]
Plant structures or organs fulfil specific functions, and those functions determine the structures that perform them. Among terrestrial (land) plants, the vascular and non-vascular plants (Bryophytes) evolved independently in terms of their adaptation to terrestrial life and are treated separately here (see Bryophytes ).
A seed plant or spermatophyte (lit. ' seed plant ' ; from Ancient Greek σπέρματος ( spérmatos ) 'seed' and φυτόν (phytón) 'plant'), also known as a phanerogam (taxon Phanerogamae ) or a phaenogam (taxon Phaenogamae ), is any plant that produces seeds .
In seed plants, a structure called the ovule contains the female gametophyte. The gametophyte produces an egg cell. After fertilization, the ovule develops into a seed containing the embryo. [14] In flowering plants, the female gametophyte (sometimes referred to as the embryo sac) has been reduced to just eight cells inside the ovule.
Human embryonic development covers the first eight weeks of development, which have 23 stages, called Carnegie stages. At the beginning of the ninth week, the embryo is termed a fetus (spelled "foetus" in British English). In comparison to the embryo, the fetus has more recognizable external features and a more complete set of developing organs.
It is uncommon for pathogens to be transmitted from the plant to its seeds (in sexual reproduction or in apomixis), though there are occasions when it occurs. [2] [page needed] Seeds generated by apomixis are a means of asexual reproduction, involving the formation and dispersal of seeds that do not originate from the fertilization of the embryos.
An endosperm is formed after the two sperm nuclei inside a pollen grain reach the interior of a female gametophyte or megagametophyte, also called the embryonic sac.One sperm nucleus fertilizes the egg cell, forming a zygote, while the other sperm nucleus usually fuses with the binucleate central cell, forming a primary endosperm cell (its nucleus is often called the triple fusion nucleus).
Many seeds are edible and the majority of human calories comes from seeds, [61] especially from cereals, legumes and nuts. Seeds also provide most cooking oils, many beverages and spices and some important food additives. In different seeds the seed embryo or the endosperm dominates and provides most of the nutrients.