what actually happens when a seed germinates?

Answer 1

The term germination is applied to the resumption of the growth of the seed embryo after the period of dormancy. Germination does not take place unless the seed has been transported to a favorable environment by one of the agencies of seed dispersal. The primary conditions of a favorable environment are adequate water and oxygen and suitable temperature. Different species of plants germinate best in different temperatures; as a rule, extremely cold or extremely warm temperatures do not favor germination. Some seeds also require adequate exposure to light before germinating.

During germination, water diffuses through the seed coats into the embryo, which has been almost completely dry during the period of dormancy, causing a swelling of the seed; the swelling is often so great that the seed coat is ruptured. With the absorption of oxygen by the seed, energy is made available for growth. The foodstuffs stored in the endosperm or in the cotyledons are broken down by enzymes into simpler substances that are transported through the embryo to the various centers of growth. The radicle is the first portion of the embryo to break through the seed coat. It develops root hairs that absorb water and attach the embryo to particles of soil. The hypocotyl then lengthens, bringing the plumule and often the cotyledon or cotyledons above the surface of the soil. If the cotyledons are brought into light, they develop chlorophyll and carry on photosynthesis until the true foliage leaves develop from the plumule. In many plants, especially members of the grass family, the cotyledons never appear above the surface of the soil, and photosynthesis does not occur until true leaves develop; the plant meanwhile subsists on food stores in the seed. From the time of germination until the plant is completely independent of food stored in the seed, the plant is known as a seedling.

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Answer 2

Actually seed germination follows three stages according to physiological processes.

Stage One - Activation:
Imbibition of water is the first process that occurs during activation. Once imbibition of water has occurred, activation or the synthesis of enzymes is initiated. These enzymes function in the breaking down of storage material within the seed (such as Starch) into simpler compounds such as sugars, which are utilized by the embryo for germination. Other enzymes activated during respiration start breaking down sugars for the production of energy that the developing seedling can use for growth and development. At the end of activation cell elongation and radicle emergence occur - the first visible (outward) sign that germination has commenced.

Stage Two - Digestion and Translocation:
During digestion and translocation, enzymes that were synthesized or activated begin to break down storage material within the seed into simple compounds which are translocated to the embryo axis or plumule and root or radicle. The plumule will grow and develop as cells elongate and divide.

Phase Three - Seedling Growth:
The germinating seed continues to undergo metabolic changes culminating into a seedling. Seedling growth can be of two types: epigeous germination or hypogeous germination. Both refer to the position of the cotyledons during germination. In epigeous germination (epi - Latin meaning above or beyond), the cotyledons are pushed above the soil surface Beans and other legumes are examples. In hypogeous germination (hypo - Latin meaning under), the cotyledons as well as most of the seed remains underground with only the shoot emerging from the soil surface.

Answer 3

The nacent enzymes get wet. That's how everything starts. The enzymes start cell division, start turning starch into sugar & then into other things. Until light hits the sepals (the 2 first sort of leaves that come up) all the tiny plant's energy has to come from what was in the seed, & that's unlocked through the power of enzymatic activity.

;-)

Answer 4

seeds germinates when it find waters. the water will enter the seeds through osmotic phenomena. and react with the substabce inside the seeds.