Ans.
Sickle-cell disorder is a genetic disorder, which shows defected red blood cells, due to mutation in the genes for hemoglobin protein.
Malaria is common in sub-Saharan Africa region and there, natural selection favored gene for sickle cells, because it might be beneficial to people having sickle cell disease that makes them able to survive in such condition and transmit their genes to offspring.
On the other hand, in those Africans, who moved to United States, where malaria is uncommon or absent, natural selection favored normal, wild type genes, resulting in fewer people with defected sickle cell.
Hence, sub-Saharan African population shows higher percentage of mutated gene for sickle cell as compared to population of United States.
Thus, the evolutionary process behind this difference is 'natural selection.'
Answer:
Incomplete dominance is when a dominant allele, or form of a gene, does not completely mask the effects of a recessive allele, and the organism's resulting physical appearance shows a blending of both alleles. ... Note that this is different from codominance, which is when both alleles are expressed at the same time.
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Answer:
Zero latitude
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The difference is high is hotter and low is colder
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Dinosaurs are living organisms that depends on the environment for survival. As the asteroid hits the Yucatan Peninsula area about 66 million years a couple of things can happen:
Frictional heating of the surface as the earth collided with the asteroid. This heating will cause surface temperature to rise globally and can induce the phenomenon of global warming. This can lead to release of water from reservoirs on the earth surface and hence flooding.
The impact can lead to increase in surface pressure beyond normal and that which life has adjusted to.
Debris in form of dust will be released into the atmosphere and a global air pollution will occur. Gases useful for life will be highly polluted by the vast amount of dusts and other particles discharged into the atmosphere.
