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.'
Answer:
The prey population, the rabbits, and the predator population, the foxes, directly rely on one another. As the rabbit population grows, more food becomes available for the fox population to grow, therefore the fox population grows. The rabbit population now has more predators, but an assumed constant amount of food, causing the rabbit population to fall. The rabbit population falls and less food becomes available for the fox population, so the fox population falls. Both the predator and prey species are majorly responsible for the carrying capacities of the other species.
The parental generation makes the F1 generation not the F2
Answer:
b. Neither the researchers nor the study participants know who is receiving the drug and who is receiving the placebo.
Explanation:
In a double-blind test, there are two groups of participants: (1) people who are receiving the new drug and (2) people who are taking a placebo. Neither people from group (1) nor people from group (2) know what they are taking. Also, researchers recollect data from theses groups without knowing which person belongs to each group to avoid any "favoritism" caused by expected results.
