Single-celled organisms, such as bacteria, protozoa, and yeast, usually reproduce asexually. Clones of these organisms are useful in research. For example, various drugs and other compounds can be tested on bacterial clones. All the test bacteria have the same genetic makeup. Therefore, any differences in effectiveness among the different compounds result from the compounds themselves and not from the bacteria.
Many plants reproduce by vegetative propagation, a form of natural cloning.
Plants that develop from runners or underground stems are clones of the plants that send out the runners and stems. Gardeners use such techniques as cuttage, grafting, and mound layering to produce clones of favored plants. World Book illustration by Marion Pahl Algae, fungi, and such simple plants as club mosses can reproduce asexually as well as sexually and can be cloned. Higher plants usually reproduce sexually and form seeds. Plant clones are useful for measuring the effects of various environmental factors or chemical compounds on genetically identical plants.