External exchange of gases
The fact that it rotates on an axis and rotates around the sun causes the seasons to change over a year. Once every year it orbits around the sun and based on the placing of the Earth it depicts the season.
Make an observation.
Ask a question.
Form a hypothesis, or testable explanation.
Make a prediction based on the hypothesis.
Test the prediction.
Iterate: use the results to make new hypotheses or predictions.
I hope this helps you.
Research indicates that stress can produce direct physiological effects such as elevated blood pressure, increased hormonal activity, and decrease in immune system functioning. Or, in other words, all except psychological disorders.
