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At least one of the spores develop into haploid female gametophytes, the megagametophytes. [1] The megaspore mother cell arises within the megasporangium tissue. In flowering plants the megasporangium is also called the nucellus, and the female gametophyte is sometimes called the embryo sac or embryonic sac.
The bisporic pattern is characterized by cell plate formation only after meiosis 1, and results in two two-nucleate megaspores, of which one degenerates. The tetrasporic pattern is characterized by cell plates failing to form after either meiosis 1 or 2, and results in one four-nucleate megaspore.
This megasporocyte undergoes meiotic cell division to form four cells that are haploid. Three cells die and one that is most distant from the micropyle develops into the megaspore. This megaspore becomes larger and the nucleus of it undergoes mitosis three times until there are eight nuclei. These eight nuclei are then arranged into two groups ...
Also inheritance. The storage, transfer, and expression of genetic information in biological organisms, [14] as manifested by the passing on of phenotypic traits from parents to their offspring, either through sexual or asexual reproduction. Offspring cells or organisms are said to inherit the genetic information of their parents. heritability 1.
The generally accepted parts of modern cell theory include: All known living things are made up of one or more cells [13] All living cells arise from pre-existing cells by division. The cell is the fundamental unit of structure and function in all living organisms. [14] The activity of an organism depends on the total activity of independent ...
Mendelian inheritance (also known as Mendelism) is a type of biological inheritance following the principles originally proposed by Gregor Mendel in 1865 and 1866, re-discovered in 1900 by Hugo de Vries and Carl Correns, and later popularized by William Bateson. [1] These principles were initially controversial.
Image from his textbook The Cell in Development and Inheritance, second edition, 1900. Edmund Beecher Wilson (October 19, 1856 – March 3, 1939) [2] was a pioneering American zoologist and geneticist. He wrote one of the most influential textbooks in modern biology, The Cell. [3] [4] He discovered the chromosomal XY sex-determination system in ...
His main contribution involved germ plasm theory, at one time also known as Weismannism, [1] according to which inheritance (in a multicellular animal) only takes place by means of the germ cells—the gametes such as egg cells and sperm cells. Other cells of the body—somatic cells—do not function as agents of heredity. The effect is one ...