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Long Answer TypeWhat is feedback control ? Illustrate feedback mechanism of homeostasis by an example of hormones.
There are three general types of the endosperm formation :
(1) Nuclear type (2) Cellular type (3) Helobial type
(1) Nuclear type : In this type, the first division and usually several of the following divisions are unaccompnied by wall formation. The nuclei may either remain free or in later stages. They may become separated by walls. As divisions progress, the nuclei are being pushed towards the periphery, thus a large central vacuole is formed. Often the nuclei are especially aggregated at the micropylar and chelazal ends of the sac and form only a thin layer at the sides.
(2) Cellular type : In this type, the first and the most of the following divisions are accompanied by wall formation and thus the sac is divided into several chambers, some of which may contain more than one nucleus. The first wall is usually transverse but sometimes vertical or obligue and in some other cases, the plane of division is not constant.
(3) Helobial type : This type is frequently found in the members of the order helobiales. In this type the first division is followed by a transverse wall resulting in a micropylar and chalazal chamber. Further divisions are generally free nuclear and may be formed by the micropylar chamber only.
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