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Heterospory evolved due to natural selection that favoured an increase in propagule size compared with the smaller spores of homosporous plants. [2] Heterosporous plants, similar to anisosporic plants [clarification needed], produce two different sized spores in separate sporangia that develop into separate male and female gametophytes.
The main difference between spores and seeds as dispersal units is that spores are unicellular, the first cell of a gametophyte, while seeds contain within them a developing embryo (the multicellular sporophyte of the next generation), produced by the fusion of the male gamete of the pollen tube with the female gamete formed by the ...
This is illustrated by Reichardt's dye, as shown in the image. Negative solvatochromism corresponds to a hypsochromic shift (or blue shift) with increasing solvent polarity. An examples of negative solvatochromism is provided by 4-(4 ′-hydroxystyryl)-N-methylpyridinium iodide, which is red in 1-propanol, orange in methanol, and yellow in water.
Acid dyes are water-soluble anionic dyes that are applied to fibers such as silk, wool, nylon and modified acrylic fibers using neutral to acid dye baths. Attachment to the fiber is attributed, at least partly, to salt formation between anionic groups in the dyes and cationic groups in the fiber.
Another example of a leuco dye is the crystal violet lactone, which in its lactone form is colorless or slightly yellowish, but in low pH, when it is protonated, it becomes intensely violet. [1] Other examples are phenolphthalein and thymolphthalein , colorless in acidic to neutral pH, but becoming pink and blue in alkaline environment.
Reactive dyes have good fastness properties owing to the covalent bonding that occurs during dyeing. Reactive dyeing is the most important method for coloring cellulose fibers . Reactive dyes can also be applied on wool and nylon ; in the latter case they are applied under weakly acidic conditions.
Rhodamine 6G / ˈ r oʊ d əm iː n / is a highly fluorescent rhodamine family dye. It is often used as a tracer dye within water to determine the rate and direction of flow and transport. Rhodamine dyes fluoresce and can thus be detected easily and inexpensively with instruments called fluorometers.
Smith et al. (2006) carried out the first higher-level classification of ferns based on molecular phylogenetics. They included heterosporous water ferns ( Salviniales ) (placed in a separate subclass by Cronquist et al. due to their highly modified morphology) within the leptosporangiate ferns, which they elevated to the rank of class as the ...