Nostocs are able to perform photosynthesis without chloroplasts. Instead these bacterium rely on photosynthetic pigments that are located in their cytoplasm. Similar to other forms of bacteria, the single-celled Nostoc does not have a nucleus or other internal membrane systems and the cytoplasm is comprised of between seventy and eighty-five percent water. Without the assistance of internal structures or whip-like appendages, the bacteria are able to move about in a swaying motion possibly in response to electromagnetic stimulation of their pigments. The chloroplast organelles (actually pigmented protoplasmic bodies) found in modern plants are thought by some scientists to be derived from a precursor cyanobacterium through an evolutionary chain of events.