Answer:
So they are lighter and move quicker.
Explanation:
With the small wings and bodies birds have it would be hard for them to escape predators and lift their own weights if their bones were dense like humans' bones. The hollow part of the birds' bone is connected to their lungs so they have enough oxygen to fly easily. Hope this can help you! :)
Answer:
Heart disease affects the respiratory system by causing irregularities in the way fluid is carried away from the lungs. Looking after your heart health is extremely important for your whole body, especially your lungs.
I THINK THE ANSWER IS ::Tissues composed of more than one cell type are generically referred to as complex tissues. Xylem and phloem are the two most important complex tissues in a plant, as their primary functions include the transport of water, ions and soluble food substances throughout the plant.
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