tugas kelompok Biology tentang "Seeds"

SEED

( BIOLOGY TASK – Group 4 )

Created by         : Ainnur Istafada

                               Elisabeth Ivana Maureen K

                               Rr. Faizah Shinta Prabandari

                               Shafira Azzahra

                               Via Valencia Arifin

Seed

A seed is a small embryonic plant enclosed in a covering called the seed coat. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant. The formation of the seed completes the process of reproduction in seed plants (started with the development of flowers and pollination), with the embryo developed from the zygote and the seed coat from the integuments of the ovule.  A typical seed includes three basic parts: (1) an embryo, (2) a supply of nutrients for the embryo, and (3) a seed coat.

  

Seeds have been an important development in the reproduction and spread of flowering plants, relative to more primitive plants like mosses, ferns and liverworts, which do not have seeds and use other means to propagate themselves. This can be seen by the success of seed plants (both gymnosperms and angiosperms) in dominating biological niches on land, from forests to grasslands both in hot and cold climates. Seed also has fuction to keep the food reserve and the plants spreader. The dispersal of seed is done by the the help of wind, water, and human.

                                

Parts of Seed

Every embryo in ovule consist of radicle, seed leaves, and seed stem. The radicle is a root to be. The seed leaves (cotyledon) is the first leaf of plant, with functioned for the place of photosynthesis before the real leaves formed and as the place to keep the food reserve such as in the legume of various shorts. The seed stem is divided into two kinds. Those are segment on the seed leaves and stem segment under the seed leaves. The seed leave and stem is often called plumule.

In the Angiosperm, such as in mango and rambutan, the ovule is enclosed by the ovary; while n the Gymnosperm, such as in melinjo and cycad, the ovule is not covered by the ovary.

Seed Germination

Seed germination is a process by which a seed embryo develops into a seedling. It involves the reactivation of the metabolic pathways that lead to

growth and the emergence of the radicle or seed root and plumule or shoot. The emergence of the seedling above the soil surface is the next phase of the plants growth and is called seedling establishment.

Three fundamental conditions must exist before germination can occur. (1) The embryo must be alive, called seed viability. (2) Any dormancy requirements that prevent germination must be overcome. (3) The proper environmental conditions must exist for germination.

Seed Dispersal

Seed dispersal is seen most obviously in fruits, however many seeds aid in their own dispersal. Some kinds of seeds are dispersed while still inside a fruit or cone, which later opens or disintegrates to release the seeds. Other seeds are expelled or released from the fruit prior to dispersal. For example, milkweeds produce a fruit type, known as a follicle,  that splits open along one side to release the seeds. Iris capsules split into three "valves" to release their seeds.

By wind

(Dandelion seeds (achenes) can be carried long distances by the wind)

• Many seeds have a wing that aids in wind dispersal.
• The dustlike seeds of orchids are carried efficiently by the wind.
• Some seeds (have hairs that aid in wind dispersal).

By water (hydrochory)

• Some plants, such as Mucuna and Dioclea, produce buoyant seeds termed sea-beans or drift seeds because they float in rivers to the oceans and wash up on beaches.

By animals (zoochory)

• Seeds (burrs) with barbs or hooks which attach to animal fur or feathers, and then drop off later.
• Seeds with a fleshy covering are eaten by animals (birds, mammals, reptiles, fish) which then disperse these seeds in their droppings.
• Seeds (nuts) which are an attractive long-term storable food resource for animals, the seeds are stored some distance from the parent plant, and some escape being eaten if the animal forgets them.

Characteristics and differences plant of monocots and dicots / seed pieces one and two

Plants can be divided into two kinds, there are plants that have one piece seed / monocotyledone and plants that have two pieces seed / dicotyledone.

These are the characteristics and differences plant of monocots and dicots / seed pieces one and two :

Morphology	Monocots	Dicots
Root forms	Having a system of root fibers	Has ride system of root
Bone leaf	Curved or parallel	Pinnate or forms such as fingers
The number of pieces of seeds or cotyledons	One piece of fruit seeds	Two piece of fruit seeds
The content of roots and stems	There is no cambium	There is Cambium
The number of petals	Generally is a multiple of three	Usually a multiple of four or five
Example plants	Coconut, Corn, and so forth.	Peanut, Mango, Rambutan, Star Fruit, and others.

 

The Opened and Closed Seed Plants

Seed plants (Spermatophyta) is a plant that has a section called seeds. Basically, the seed plant characterized by the flower so often referred to flowering plants (Anthopyta). How does the formation process of seed? Seeds produced by flowers after pollination and  fertilization events. In other words, the seeds can be produced is a means of sexual  propagation  (generative). In addition, there are  also  breeding  asexually (vegetative).

Plant seeds are regrouped into two divisions, there are open seed plants  (gymnosperms) and seed plant closed (Angiospermae). In the open seed plants, seeds covered with leaves or fruit pulp (karpelum). For example, on fir, pine, and amber. Meanwhile, the seed plant closed, cover the  seeds in the fruit flesh or fruit leaves. For example, on mango, durian,  andorange.

Source : www.wikipedia.org