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Circulation and Excretion › View

What regulates human respiration rate?

A. oxygen levels

B. carbon monoxide levels

C. carbon dioxide levels

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Biochemistry › View

Which of the following is true about DNA and RNA?

A. Both DNA and RNA are usually single-stranded

B. Both DNA and RNA are usually double-stranded

C. DNA is usually double-stranded and RNA is usually single-stranded

D. DNA is usually single-stranded and RNA is usually double-stranded

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