Why is the poly-A tail added to mRNA before it leaves the nucleus?
a. It provides a destination for movement in the cell.
b. It protects against exonuclease activity.
c. It notifies the cell that this molecule is “self.”
d. It provides the final instructions for protein synthesis.
b. It protects against exonuclease activity.
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A species' fundamental niche:
A. is smaller than its realized niche. B. is what is actually occupied by that species. C. is determined by competition between species. D. has the necessary resources and conditions for survival. E. is always occupied in full by most species.
Which of the following structural motifs promotes dimerization?
A. Zinc finger B. Leucine zipper C. Helix-turn-helix D. Helix-loop-helix
What is an example of basic research?
a. Developing a new diagnostic test b. Synthesizing proteins for treating disease c. Manufacturing a vaccine d. Developing a new drug to treat diabetes e. Learning how plants turn carbon dioxide into sugar
Halophytes are plants that live in saline soils. The high osmotic potential of the salt solution in the soil creates a very negative water potential. What can halophytes do so that water will flow into the roots?
A. They can open all their stomata so that transpiration "pulls" more water into the roots. B. They can remove the mycorrhizal fungi from their roots decreasing the competition for water. C. They can close their stomata so that less water is lost through transpiration. D. They can increase the solute concentration in their roots creating a water potential that is more negative than the soil. E. They can pump ions out of the plant creating a water potential in the roots that is more positive than the soil.