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:
Humans—and other complex multicellular organisms—have systems of organs that work together, carrying out processes that keep us alive.
The body has levels of organization that build on each other. Cells make up tissues, tissues make up organs, and organs make up organ systems.
The function of an organ system depends on the integrated activity of its organs. For instance, digestive system organs cooperate to process food.
The survival of the organism depends on the integrated activity of all the organ systems, often coordinated by the endocrine and nervous systems.
Explanation:Goblet cell in your respiratory epithelium of trachea.
Answer:
There are two main types of adaptation: physical and behavioral. Physical adaptations are special body parts that help a plant or animal survive in an environment.
Explanation:
