What force is most important in returning blood back to the heart in the veins?
A) contraction of the skeletal muscles in the body B) gravity
C) contraction of the ventricles on the heart D) osmotic pressure of proteins in the blood
Answer: A
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Coccolithophores and foraminiferans both use ________ to form their exoskeletons
A) Si4+ B) Fe3+ C) Ca2+ D) HPO4-
Haploid genotypes involving two loci, such as AB, Ab, aB, and ab, are known as an organism's ________
Fill in the blank(s) with correct word
The most distinctive characteristic of leaf mesophyll cells is that they are filled with
A. stomata. B. many chloroplasts. C. veins. D. central vacuoles. E. oxygen bubbles.
A substance that may trigger an immune response, if presented in the right context is termed a(n)
A) cytokine. B) antigen. C) effector. D) antibody. E) hapten.