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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).
Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...
Usually in germination, the breakdown of starch to glucose in the endosperm begins shortly after the seed is exposed to water. [10] Gibberellins in the seed embryo are believed to signal starch hydrolysis through inducing the synthesis of the enzyme α- amylase in the aleurone cells.
After entering an ovule through the micropyle, one male nucleus fuses with the polar bodies to produce the endosperm tissues, while the other fuses with the egg cell to produce the embryo. [3] [4] Hence the term: "double fertilisation". This process would result in the production of a seed, made of both nutritious tissues and embryo.
The endosperm is surrounded by the aleurone layer (peripheral endosperm), filled with proteinaceous aleurone grains. Originally, by analogy with the animal ovum, the outer nucellus layer was referred to as albumen, and the inner endosperm layer as vitellus. Although misleading, the term began to be applied to all the nutrient matter.
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A refined grain is defined as having undergone a process that removes the bran, germ and husk of the grain and leaves the endosperm, or starchy interior. [1] Examples of refined grains include white bread, white flour, corn grits and white rice. [2] Refined grains are milled which gives a finer texture and improved shelf life. [3]
Detailed illustration of the different parts constituting a wheat kernel. The germ of a cereal grain is the part that develops into a plant; [1] it is the seed embryo. [2] Along with bran, germ is often a by-product of the milling [3] that produces refined grain products.