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.'
Question 4
Which of the following would be considered a form of active transport?
o the movement of oxygen molecules from high concentration in the blood to low concentration in the cell.
O the movement of carbon dioxide from high concentrations in the cell to low concentrations in the blood.
o the movement of glucose into the cell down its concentration gradient,
o the movement of sodium atoms from low concentration in the cell to higher concentrations outside the cell.
In the mitochondria of the cell
This is known as parasitism.
In biology, parasitism is a relationship between species, where one organism, the parasite, lives on or in another organism, the host, causing it some harm, and is adapted structurally to this way of life.
