Ans.
Sickle-cell disorder shows defected red blood cells, due to mutation in gene that code for hemoglobin. The mutated genes for sickle-cell disease are found in higher percentage of sub-Saharan African population as it provides protection against malaria as compared to population of United States.
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.
Thus, the evolutionary process behind this is 'natural selection.'
1 mile.
Since he walks at a speed of 2 miles per hour, he will have only walked 1 mile after walking for half of an hour.
I believe the answer is: <span>Spores are released into the environment and grow into male and female gametophytes.
This Phase happens after </span>a haploid egg cell is fertilized by a haploid <span>sperm and then released to the environment. . This will result on Double sites of chromosomes that held by each parent (</span><span>grow into male and female gametophytes.)</span>
