Although the actual questions are missing from your ask, here's how you can tell.
If the study will be messed up (added bias) through interaction with the subjects the study should be observational. For example if a biologists wanted to study the eating habits of wild birds in the tropics, they would need to do an observational study. if they did a controlled experiment, the birds will change their eating habits based on human interaction, thus making the study invalid.
If the study requires specific measurements, close monitoring, or contact and interaction with the subjects the study should be a controlled experiment. For example, if a scientist wanted to test out a new drug, the health of patients would need to be closely monitored.
Answer:
the last one
Explanation:
loose clothing doesn't overheat the body causing you not to sweat. sweating is a way the body loses hydration so wearing loose and light clothing prevents you from sweating
The solvent would be the water and the sugar would be the solute.
Answer:
Yes both are different. In directional selection one of the extreme traits is favored, whereas in disruptive selection both the extreme traits are favored.
Explanation:
Directional: If selection acts to eliminate one extreme form and supports the other extreme then the peak shifts in the direction which is selected by the nature.
Disruptive: If the selection does not favor the mean character value, rather favors both the peripheral character values then this kind of selection is called disruptive selection.
Answer:
They protect you against illness and disease. Think of white blood cells as your immunity cells. In a sense, they are always at war. They flow through your bloodstream to fight viruses, bacteria, and other foreign invaders that threaten your health.
