16. Which of the following causes the brain to stimulate faster breathing? high levels of oxygen in blood
low levels of oxygen in blood
high levels of carbon dioxide in blood
low levels of carbon dioxide in blood
Sao

high levels of oxygen in blood

desert perennials often survive by remaining dormant during dry periods of the year, then springing to life when water becomes available. most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.

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