Please help.in a hurry?

Question

ok i have 2 questions

1 is how does the seed of an angiosperm develope ?

2 is what is the function of flowers?

Answer 1

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http://users.rcn.com/jkimball.ma.ultrane...

Double fertilization

The pollen tube enters the ovule through the micropyle and ruptures.

    * One sperm cell fuses with the egg forming the diploid zygote.

    * The other sperm cell fuses with the polar nuclei forming the endosperm nucleus. Most angiosperms have two polar nuclei so the endosperm is triploid (3n).

    * The tube nucleus disintegrates.

Flowers develop from flower buds. Each bud contains 4 concentric whorls of tissue. From the outer to the inner, these develop into

    * a whorl of sepals (collectively called the calyx)

    * a whorl of petals (collectively called the corolla)

    * stamens in which the microsporangia form

    * carpels in which the megasporangia form.

Answer 2

i don't know the first one but the second one is: flowers are the fruit of the plant they make the seeds so that the plant can reproduce it's self (not shure but i have a good feeling thats the answer)

Answer 3

not sure about 1 but 2.The biological function of a flower is to mediate the union of male sperm with female ovum in order to produce seeds.

Answer 4

Seeds

After double fertilization, each ovule develops into a seed, which consists of

a plumule, made up of

two embryonic leaves, which will become the first true leaves of the seedling, and

a terminal (apical) bud. The terminal bud contains the meristem at which later growth of the stem takes place.

One or two cotyledons which store food that will be used by the germinating seedling.

Angiosperms that produce seeds with two cotyledons are called dicots. Examples: beans, squashes, Arabidopsis

Angiosperms whose seeds contain only a single cotyledon are monocots. Examples: corn and other grasses.

The hypocotyl and radicle, which will grow into the part of the stem below the first node ("hypocotyl" = below the cotyledons) and primary root respectively.

The development of each of the parts of the plant embryo depends on gradients of the plant hormone, auxin.

In addition to the embryo plant (derived from the zygote), each seed is covered with protective seed coats derived from the walls of the ovule.



The food in the cotyledons is derived from the endosperm which, in turn, received it from the parent sporophyte. In many angiosperms (e.g., beans), when the seeds are mature, the endosperm has been totally consumed and its food transferred to the cotyledons. In others (some dicots and all monocots), the endosperm persists in the mature seed.

The seed is thus a dormant embryo sporophyte with stored food and protective coats. Its two functions are

dispersal of the species to new locations (aided in angiosperms by the fruit)

survival of the species during unfavorable climatic periods (e.g., winter). "Annual" plants (e.g., beans, cereal grains, many weeds) can survive freezing only as seeds. When the parents die in the fall, the seeds remain alive — though dormant— over the winter. When conditions are once more favorable, germination occurs and a new generation of plants develops.

Angiosperms are the flowering plants (today the most abundant and diverse plants on earth).

Most are terrestrial and all lack locomotion. This poses several problems.

Gametes are delicate single cells. For two plants to cross fertilize, there must be a mechanism for the two gametes to reach each other safely.

There must also be a mechanism to disperse their offspring far enough away from the parent so that they do not have to compete with the parent for light, water, and soil minerals.

The functions of the flower solve both of these problems.

The Flower and Its Pollination

In angiosperms, meiosis in the sporophyte generation produces two kinds of spores.

microspores

which develop in the microsporangium and

which will germinate and develop into the male gametophyte generation and

megaspores

which develop in the megasporangium and

which will develop into the female gametophyte generation