I’m pretty sure it’s water, oxygen, and food. beacuse food provided both nutrients and an energy source.
Answer: birds
Explanation: because birds have wings and they can fly
Answer: pretty sure it’s the number of mitochondria in muscle cells
Explanation:
Bonjour,
1. Arteries carry blood from the heart to the rest of the body, whereas veins carry blood from the rest of the body back to the heart.
2. Almost all arteries carry oxygenated blood and almost all veins carry deoxygenated blood.
3. Arteries have a thick elastic muscle layer, whereas the muscle layer for veins is much thinner.