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The cell nucleus (from Latin nucleus or nuculeus 'kernel, seed'; pl.: nuclei) is a membrane-bound organelle found in eukaryotic cells.Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many.
In the most common kind of mixed mating system, individual plants produce a single type of flower and fruits may contain self-fertilised, outcrossed or a mixture of progeny types. The transition from cross-fertilisation to self-fertilisation is the most common evolutionary transition in plants, and has occurred repeatedly in many independent ...
Commonly known as the bird's nest fungi, their fruiting bodies resemble tiny egg-filled birds' nests. As they are saprobic , feeding on decomposing organic matter , they are often seen growing on decaying wood and in soils enriched with wood chips or bark mulch ; they have a widespread distribution in most ecological regions.
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).
Nucleus: The nucleus of the cell functions as the genome and genetic information storage for the cell, containing all the DNA organized in the form of chromosomes. It is surrounded by a nuclear envelope, which includes nuclear pores allowing for the transportation of proteins between the inside and outside of the nucleus. [15]
The flowers of many species of Angiosperm have evolved to attract and reward a single or a few pollinator species (insects, birds, mammals). Their wide diversity of form, colour, fragrance and presence of nectar is, in many cases, the result of coevolution with the pollinator species.
Avian flu has been around and infecting wild birds and poultry since 1996. There have been nearly 1,000 known cases of bird flu in humans (889 between 2003 and May 3, 2024, according to the World ...
Self-pollination occurs when pollen from one flower pollinates the same flower or other flowers of the same individual. [45] It is thought to have evolved under conditions when pollinators were not reliable vectors for pollen transport, and is most often seen in short-lived annual species and plants that colonize new locations. [ 46 ]