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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 ...
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.
[9] In algae, akinetes form when environmental signals indicate impending change unfavorable to growth, such as the arrival of winter. Like cyanobacterial akinetes, they accumulate storage materials, but also develop thick cell walls and suspend active metabolism. [10] When conditions improve, the akinete germinates via the cell wall breaking ...
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.
The list of organisms by chromosome count describes ploidy or numbers of chromosomes in the cells of various plants, animals, protists, and other living organisms.This number, along with the visual appearance of the chromosome, is known as the karyotype, [1] [2] [3] and can be found by looking at the chromosomes through a microscope.
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.
A similar pattern of reaction times is found in young children, although with steeper slopes for both the subitizing range and the enumeration range. [6] This suggests there is no span of apprehension as such, if this is defined as the number of items which can be immediately apprehended by cognitive processes, since there is an extra cost ...
Cocci is an English loanword of a modern or Neo-Latin noun, which in turn stems from the Greek masculine noun κόκκος (cóccos) meaning 'berry'. [ 6 ] Important human diseases caused by coccoid bacteria include staphylococcal infections, some types of food poisoning , some urinary tract infections , toxic shock syndrome , gonorrhea , as ...