Why are respiratory systems necessary for complex, multicellular organisms?
What will be an ideal response?
Ans: Simple diffusion is inadequate to deliver oxygen and remove carbon dioxide from tissues more than a few cell layers removed from the air interface.
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Atoms containing a specific number of protons are called:
A. molecules B. minerals C. metals D. elements
The largest portion of most mature dicot seeds is (are)
a. the hypocotyl. b. the epicotyl. c. the radical. d. endosperm. e. cotyledons.
Intrinsic pacemaker cells are located in the ____
a. Purkinje fibers b. Bundle branches c. AV node d. SA node e. gap junctions
Alison was looking at a tissue under a microscope. It had cells within lacunae, and the matrix was glassy-looking. What type of tissue was she looking at?
A. adipose B. areolar C. bone D. blood E. cartilage