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.'
The correct answer is A.
Explanation:
EPA History. Born in the wake of elevated concern about environmental pollution, EPA was established on December 2, 1970 to consolidate in one agency a variety of federal research, monitoring, standard-setting and enforcement activities to ensure environmental protection.
I took this quiz and got it correct
Answer:
1 Tell them with videos the real dangers and effects of everyone of the drugs
2 Tell the parents to speak to them
3 inform them of the danger of sexual relations with people the do not know well
4 tell them that under no circumstances they should drive if the drink alcohol
5 Talk to them about the immense possibilities they have in front of them and they will get their dreams true if they work hard , they are honest and respect people .
Methane the most, small amount of oxygen and other gases
Answer:
B. Savanna
Explanation:
Savannas are a transitional biome, not really a forest and not really a desert – just somewhere in between. This habitat is home to many different species of plants and animals around the world, and in Africa it is home to the largest land mammal in the world – the African elephant.
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