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The basic number of chromosomes in the somatic cells of an individual or a species is called the somatic number and is designated 2n. In the germ-line (the sex cells) the chromosome number is n (humans: n = 23). [4] [5] p28 Thus, in humans 2n = 46. So, in normal diploid organisms, autosomal chromosomes are present in two copies.
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 most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms. Most are derived from the amino acid tyrosine. Eumelanin is found in hair, areola, and skin, and the hair colors gray, black, blond, and brown. In humans, it is more abundant in people with dark skin.
Dark skin is a type of human skin color that is rich in melanin pigments. [1] [2] [3] People with dark skin are often referred to as black people, [4] although this usage can be ambiguous in some countries where it is also used to specifically refer to different ethnic groups or populations. [5] [6] [7] [8]
Monochromacy (from Greek mono, meaning "one" and chromo, meaning "color") is the ability of organisms to perceive only light intensity without respect to spectral composition. Organisms with monochromacy lack color vision and can only see in shades of grey ranging from black to white. Organisms with monochromacy are called monochromats.
The Fischer–Saller scale, named after Eugen Fischer and Karl Saller is used in physical anthropology and medicine to determine the shades of hair color. The scale uses the following designations: A (very light blond), B to E (light blond), F to L (), M to O (dark blond), P to T (light brown to brown), U to Y (dark brown to black) and Roman numerals I to IV and V to VI (red-blond).
Magenta is variously defined as a purplish-red, reddish-purple, or a mauvish–crimson color. On color wheels of the RGB and CMY color models, it is located midway between red and blue, opposite green. Complements of magenta are evoked by light having a spectrum dominated by energy with a wavelength of roughly 500–530 nm.
[50] [51] The differences in color are mainly caused by higher levels of melanin in the skin, hair and eyes in males. [52] [53] In one study, almost twice as many females as males had red or auburn hair. A higher proportion of females were also found to have blond hair, whereas males were more likely to have black or dark brown hair. [54]