Answer:
The percentage of people carrying sickle cell gene increases.
Explanation:
People carrying the Sickle Cell gene have low chance of Malaria because the sickle cell enables the body to detoxify abnormal red blood cells from the body. When the malarial parasite attacks on the cells of the body, the molecular machinery for cleaning up the waste is already present in the body. Those places where malaria is common, the people having sickle cell because the sickle cell show resistance against malarial disease.
Answer;
D. controlled
An experiment in which only one variable is changed is a controlled experiment.
Explanation;
-A control experiment is an experiment where the researcher only changes one variable at a time in order to isolate the results.
In a controlled experiment, most conditions are constrained so that they do not change. One or two other conditions are then changed and measured by the experimenter. These are known as the independent variables.
For example; An experiment where all subjects involved in the experiment are treated exactly the same except for one deviation.
Unlike arteries, veins contain valves that ensure blood flows in only one direction. (Arteries don't require valves because pressure from the heart is so strong that blood is only able to flow in one direction.) Valves also help blood travel back to the heart against the force of gravity.
Answer:
Microvilli is very common in these cells. They increase the absorption area.
Explanation:
Epithelial cell surfaces show different structure shapes that allow the cells to adapt to and accomplish their functions. Most of these structures are related to the absorption surface and the need to move substances.
The development of microvilli is very common in epithelial cells. These are folds or finger-like projections emerging from the apical surface of the cell. <u>Their principal function is to absorb</u>. The microvilli of the intestinal epithelium are very uniform in size and distribution.
