BSince 11 have neither, 56-11=45have blue eyes and/or spots, so 34 have spots, 45-34=11 spotless dogs have blue eyes, and 23-11 have both.在56只狗中,有34只狗有斑点,23只狗有蓝眼睛,11只狗两者都没有.有多少既有蓝色的眼睛又有斑点( ).A.6B.12C.24D.31由于11只狗两者都没有,56-...
common ancestor.A team at the University ofCopenhagen have tracked down a genetic mutation (突变)which took place 6,000-10,000 years ago and is the causeot the eye colour of all blue-eyed humans alive on theplanet today.“Originally, we all had brown eyes,” said ProfessorHans Eiberg. ...
Archocentrus spilurumhas a rather deep body where the forehead rises sharply from the mouth. If you see a fish with a hump on its head, it is an old male. The main body color varies from olive-green to a yellowish brown, and both sexes sports a golden yellow color from the mouth do...
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故选C。2. 根据第三段The switch does not, however, turn off the gene entirely, but rather limits its action to reducing the production of melanin in the eyeball-effectively turning brown eyes to blue.(然而,这个开关并没有完全关闭该基因,而是限制了它的作用,减少眼球中黑色素的产生——有效地将...
eyes or skin colour.Variation in the colour of the eyes from brown to green can all be explained by the amount of melanin in the eyeballs, but blue-eyed individuals only have a small degree of variation in the amount of melanin in their eyes.“From this we can conclude that all blue-...
Adult male Blue-winged Teals have a light brown body covered in black spots. They have a dark bluish-gray head with a white crescent running vertically between their eyes and their black bill. Their wings and rear are also black, excluding the white patch near the rear. ...
The larger eyespots may deter predators, who at first glance could think the eyes belong to a larger creature. The underside of a blue morpho butterfly's wings. When the Blue Morpho flies, its wings flash from brilliant blue to dull brown. This makes the butterfly seem to continuously app...
A region of the nearby HERC2 gene also controls the activity (expression) of the OCA2 gene, turning it on or off as needed. So, although it is uncommon, parents with blue eyes can have children with brown eyes. The good news for the recessive traits of both red hair and blue eyes ...
根据第三段的The switch, which is located in the gene neighboring to OCA2, does not, however, turn off the gene entirely, but rather limits its action to reducing the production of melanin in the eyeball-effectively turning brown eyes to blue.可知,这种转变有助于产生较少的黑色素。故选C。