From a cross of homozygous dominant and homozygous recessive parent lines with heterozygous parents, a 1:1 phenotypic ratio is seen. Two types of phenotypes will form.
A dihybrid cross involves two traits. Example: an animal with both genes for height and body coloration is taken . The height is represented as T. T is for tall characters, and t is for short characters. A homozygous dominant character is represented as TT. Homozygous recessiveness is expressed by tt.
Another gene such as body coloration is taken. Black (B) is dominant over white (b). An animal with homozygous dominant is BB. An animal having homozygous recessive is bb.
A parent with homozygous dominant for tall character and homozygous recessive for body colour is represented by TTbb. An animal that is heterozygous for height and body coloration is taken as TtBb.
From the crossing, two phenotypes are derived, such as tall black and tall white. Out of all eight individuals, four are tall black and four are tall white. The phenotypic ratio is 1:1. The cross is explained below.
Hence, two types of phenotypes will be formed with a phenotypic ratio of 1:1.
To learn more about dihybrid crosses, refer to the following link
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the cross is AAbb*AaBb
There would be 4 different genotypes and 2 different PHENOTYPES for the offspring. (From the first gene we can get AA or Aa from the second one Bb or bb)
AAbb
Aabb have the same phenotype
AABb
AaBb have the same phenotype
Africa and Asia
Europe and Africa
Europe, Africa, and Asia
The Homo ergaster occupy Africa 1.6 million years ago. Therefore, option A is correct.
The oldest early humans known to have had proportions similar to modern humans, with relatively long legs and shorter arms compared to the size of the torso, are the early African Homo erectus fossils (also known as Homo ergaster).
At the onset of the lower Pleistocene and the lowering of the environment, Homo ergaster, sometimes known as the "working man," is an extinct species of hominid (or subspecies, according to some authorities) that existed throughout eastern and southern Africa between 1.9 and 1.4 million years ago.
Thus, the Homo ergaster occupy Africa 1.6 million years ago. Therefore, option A is correct.
Learn more about Homo ergasters, here:
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Answer:
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