Answer:
tar
Explanation:
tar is the reason your lungs go black because it is evaporated into the smoke that you breathe in and is known to be the most known cause of cancer
Answer:
What do I need to do if my heart rate is below my target range during a cardio activity? What does it mean if it is too high?
Explanation:
it mean that your heart rate is going slow and that your not moving that much and that your not that active.
when your heart rate is up means that your working hard as in running doing something active.
Plants because they go through photosynthesis