Answer:
Either the cell wall or the cell membrane.
Explanation:
All cells have cell membranes which line the outside of the cell, and some cells have cell walls, which also line the outside of the cell. Since all cells have cell membranes I am inclined to believe that the correct answer would be cell membranes.
The mutation will occur on the X chromosome. Males are more susceptible to sickle cell amenia because they only carry one X chromosome instead of two when compared to a set of female chromosomes. If a female only has the mutation on one chromosome the disease will not appear. However, when a male recieves the mutation on the X chromosome, the disease would appear, because they only have one X chromosome.
The troposphere is the atmospheric layer closest to the planet and contains the largest percentage (around 80%) of the mass of the total atmosphere.