Red blood cells pick up oxygen in the lungs and carry the oxygen to all of the other cells in the body. Sickle cell anemia is a genetic
disorder in which red blood cells, normally disk shaped, become crescent (sickle) shaped when they are not carrying a large load of
me trapped in small blood vessels, block the blood flow there, and damage the
surrounding tissues. Which of the following external factors might increase the risk of tissue damage in a person with sickle cell
anemia?
A. eating a diet high in iron
B. exercising excessively
C. walking in the rain
D. avoiding smoking

B

Explanation:

It's because excessive exercise is going to lower the person's oxygen partial pressure which will cause the affected RBCs to become sickle shaped. When that happens, the cells link to each other and block capillaries that bring oxygen to the tissues and organs. This might result in congestion or ischaemia that damages the tissue.

A is false because iron is required for haemoglobin production so this shouldn't be a problem.

C has no relevance since it won't affect the person's oxygen partial pressure.

D is not going to lower the patient's oxygen partial pressure.

A scientific law is formed when the results of an experiment generate the same results every time a particular experiment is performed. A scientific law is made when something has been thoroughly tested again and again through experimentation. Unlike the theory, a scientific law is not subjected to change with time. A scientific law is accepted universally and other hypothesis can be generated based on the authenticity of the law.