The two main variables in an experiment are the independent and dependent variable.
An independent variable is the variable that is changed or controlled in a scientific experiment to test the effects on the dependent variable.
A dependent variable is the variable being tested and measured in a scientific experiment.
The dependent variable is 'dependent' on the independent variable. As the experimenter changes the independent variable, the effect on the dependent variable is observed and recorded.
For example, a scientist wants to see if the brightness of light has any effect on a moth being attracted to the light. The brightness of the light is controlled by the scientist. This would be the independent variable. How the moth reacts to the different light levels (distance to light source) would be the dependent variable.
When results are plotted in graphs, the convention is to use the independent variable as the x-axis and the dependent variable as the y-axis.
The organ is the LUNGS.
The lungs excrete carbon dioxide and water vapour through metabolism.
The lungs are used for breathing in humans, through the lungs we take in oxygen which is carried by the blood to all the part of the body and we exhale carbon dioxide which is a waste product generated as a result of the reactions that occur in the body.
Organ system is the most complex in organization
