B.
Humans are also part of ecosystems and if they cease to exist, human well being will be affected.
The highest point the medium rises to and a trough is the lowest point the medium sinks to.
Answer:
Gas exchange takes place in the millions of alveoli in the lungs and the capillaries that envelop them. As shown below, inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli.
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Chitin - part of insects hard body and part of fungus
Cellulose - part of plant cell walls
Pectin - also part of plant cell walls
