1. Air enters the nostrils.
2. Air passes from the trachea to the bronchi
3. Air diffuses from the alveoli to the blood cells.
4. Oxygen enters the blood cells.
5. Blood transports oxygen to other cells.
Answer:
B
Explanation:
because their structures become more complex. Such as the human brain, over time we get more knowledge.
Answer:
Removal of plants, and invasive species.
Explanation:
