Capillaries are the end structures in the artery system that bring oxygenated blood from your lungs to the rest of your body.
Answer:
research question: how do different humidity levels affect the heights of different types of trees
independent variable: humidity level
dependent variable: tree height
constants: temperature, light, duration of time
control group: tree left outside in normal conditions
Explanation:
The first person that answered is correct just to let you know!
This would be the nucleiod region.
