Spore

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In biology, a spore is a reproductive structure that is adapted for dispersion and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many plants, algae, fungi and some protozoans.

Spores are usually haploid and unicellular and are produced by meiosis in the sporophyte. Once conditions are favorable, the spore can develop into a new organism using mitotic division, producing a multicellular gametophyte, which eventually go on to produce gametes. Two gametes fuse to create a new sporophyte. This cycle is known as alternation of generations, but a better term is "biological life cycle", as there may be more than one phase and so it cannot be an alternation. Haploid spores produced by mitosis (known as mitospores) are used by many fungi for asexual reproduction.

Spores are the units of asexual reproduction as a single spore develops into a new organism. By contrast, gametes are the units of sexual reproduction as two gametes need to fuse to create a new organism.

The term spore may also refer to the dormant stage of some bacteria or archaea; however these are more correctly known as endospores and are not truly spores in the sense discussed in this article. The term can also be loosely applied to some animal resting stages. Fungi that produce spores are known as sporogenous, and those that do not are asporogenous.