About how much of the atmosphere is composed of nitrogen?
A) 23 percent B) 1 percent C) 78 percent D) 52 percent
Answer: C
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In which choice are the entries listed from smallest to largest?
A) DNA building block - gene - chromosome - genome B) DNA building block - RNA building block - protein C) Gene - cell - DNA - genome D) Chromosome - genome - cell - DNA building block
Which endocrine gland is the main center for control of the internal environment?
a. pineal b. hypothalamus c. thyroid d. adrenal cortex e. thalamus
__________ are teeth adapted primarily for tearing food
a. Bicuspids b. Canines c. Incisors d. Molars e. Premolars
The bicuspid (mitral) valve
A. is the location of the pacemaker cells of a normal heart. B. prevents blood flow from the right ventricle to the right atrium. C. prevents blood flow from the left ventricle to the left atrium. D. prevents blood flow from the pulmonary artery to the right ventricle. E. prevents blood flow from the aorta to the left ventricle.