_______ are complex carbon ring structures that

often have an iron atom at their center.
a. Hemes
b. Globins
c. Globulins
d. Sugars
e. Alkenes


Answer: a

Biology & Microbiology

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Honeybees must maintain specific temperatures to thrive. On hot days, the hive can quickly

overheat, so some bees will stand near the entrance and fan their wings to provide cool air currents into the hive. In winter, honeybees cluster together in their hives and vibrate their wings in a form of shivering to generate heat and maintain the hive at a constant temperature. This heating and cooling is a form of

a. homeostasis. b. evolution. c. competition. d. homology

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Food preference in garter snakes is a learned behavior

a. True b. False

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What serves as the cardiac pacemaker?

a. sinoatrial node b. atrioventricular node c. gap junction d. the left ventricle e. conducting fiber

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Following intense exercise, the human body attempts to overcome oxygen debt by

A) sweating. B) elevating heart rate. C) producing ATP. D) taking deep breaths. E) inhibiting contractions of smooth muscle.

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