The northern boundary of the distribution of Saguaro cacti is defined by

A. areas in which temperatures do not drop below freezing.
B. the availability of water year round.
C. the presence of pollinating insects.
D. proximity to coastal environments.
E. the frequency of low-intensity fires.


A. areas in which temperatures do not drop below freezing.

Biology & Microbiology

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Fill in the blank(s) with the appropriate word(s).

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The interior of a ____________________ is saltier than its freshwater habitat, so water tends to diffuse into the cell. It uses contractile vacuoles to remove excess water

Fill in the blank(s) with correct word

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At what two checkpoints does the cell check for the integrity of the DNA?

A. G1 and mitotic B. G1 and cytokinesis C. G2 and mitotic D. cytokinesis and G2 E. G1 and G2

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Which structure is a characteristic found only in angiosperms?

A. flower B. leaf C. megaphyll D. seed E. vascular tissue

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