Search results
Results From The WOW.Com Content Network
They fix nitrogen from dinitrogen (N 2) in the air using the enzyme nitrogenase, in order to provide the cells in the filament with nitrogen for biosynthesis. [2] Nitrogenase is inactivated by oxygen, so the heterocyst must create a microanaerobic environment. The heterocysts' unique structure and physiology require a global change in gene ...
Nostoc, also known as star jelly, troll's butter, spit of moon, fallen star, witch's butter (not to be confused with the fungi commonly known as witches' butter), and witch's jelly, is the most common genus of cyanobacteria found in a variety of both aquatic and terrestrial environments that may form colonies composed of filaments of moniliform cells in a gelatinous sheath of polysaccharides. [1]
Auxospores are involved in re-establishing the normal size in diatoms, as successive mitotic cell divisions leads to a decrease in cell size. This occurs because each daughter cell produced by cell division inherits one of the two valves that make up the frustule (a silica cell wall), and then grows a smaller valve within it.
[6] In cyanobacteria, akinetes usually develop in strings with each cell differentiating after another and this occurs next to heterocysts if they are present. [ 1 ] Development usually occurs during stationary phase and is triggered by unfavorable conditions such as insufficient light or nutrients, temperature, and saline levels in the ...
The Wechsler Preschool and Primary Scale of Intelligence (WPPSI) is an intelligence test designed for children ages 2 years 6 months to 7 years 7 months developed by David Wechsler in 1967. It is a descendant of the earlier Wechsler Adult Intelligence Scale and the Wechsler Intelligence Scale for Children tests. Since its original publication ...
The Differential Ability Scales (DAS) is a nationally normed (in the US), and individually administered battery of cognitive and achievement tests. Into its second edition (DAS-II), the test can be administered to children ages 2 years 6 months to 17 years 11 months across a range of developmental levels.
The Heaf test, a diagnostic skin test, was long performed to determine whether or not children had been exposed to tuberculosis infection. The test was named after F. R. G. Heaf . Also known as the Sterneedle test , [ 1 ] it was administered by a Heaf gun (trademarked "Sterneedle"), [ 2 ] a spring-loaded instrument with six needles arranged in ...
The Draw-A-Scientist Test (DAST) is an open-ended projective test designed to investigate children's perceptions of the scientist. Originally developed by David Wade Chambers in 1983, the main purpose was to learn at what age the well known stereotypic image of the scientist first appeared.