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"Protist" is an umbrella term that refers to a varied group of living organisms that have little in common other than they have nuclei within their cells and are of a relatively simple structuralorganization. The Kingdom Protista is no longer in use among modern biologists because of the broad diversity of the group. Advances in the study of genetics have led to systems of classification basedon relatedness to other organisms. In general, protists are thought to recommend the very earliest stages of biological evolution, but scientists now recognize some protists as being derived from morecomplex organisms. Reproduction in protists can be either sexual or asexual.

One amoeba splits into two
Amoebas are an example of a single-celled protist that reproduce asexually, which simplymeans a single parent produces an offspring without fertilization by another. First, the amoeba creates an exact replica of its nucleus, which is called mitosis. Then, in a process called fission,the amoeba splits itself into two cells with one nucleus in each. As a result , the pair are genetically identical. Fission is the predominant method of asexual reproduction in single-celled protists,though some fungus-like protists produce spores, another method of asexual reproduction.

Sexual reproduction in ciliate protists
Asexual reproduction produces faster population growth thansexual reproduction because it can occur more frequently and because it only requires a single parent. Many protists, however, are capable of true sexual reproduction under certain stressfulcircumstances. It is believed that environmental stress triggers the exchange of genetic material in an attempt to create offspring better suited to the environment. Sexual reproduction requires two parents toundergo the process of meiosis, which creates a special reproductive cell with exactly half a set of DNA. This is called a gamete. When the gametes of the two parents meet, a zygote is formed with a...
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