What causes the hypocotyl of dicots to
straighten?
a. Light.
b. Gravity.
c. Wind.
d. Air.
e. All of these may be involved
A
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Biological membranes are held together mainly by ____
a. hydrogen bonds between lipid molecules b. hydration layers over lipid molecules c. exclusion of the nonpolar regions of lipids by water d. hydrogen bonds between water molecules e. surface tension at the interface between layers of water molecules
In an elegant set of experiments, which protein did Anfinsen study in order to understand how the three-dimensional
structure of proteins is determined?
a. ovalbumin b. chaperonin c. ribonuclease d. insulin e. hemoglobin
The center for control of motor skills and
posture is the a. cerebrum. b. pons. c. cerebellum. d. thalamus. e. hypothalamus.
Sometimes, the most practical way to do an experiment is not to perform it in an animal, but to look at cell responses in culture. Cells from mice, humans, and other mammals have been used to establish cell culture lines that have been very important for research. You are studying a novel water-soluble mouse hormone. You know cell culture can be a practical model to reveal protein function, so you apply the hormone to yeast cells, but nothing happens. What is a likely explanation for why nothing happened in your experiment?
A. Yeast may lack the receptor required for the hormone to act. B. Water-soluble hormones are lipids, not proteins. C. Yeast have a cell wall, so the molecule cannot pass through the cell membrane as it would in mice. D. You need to apply the hormone in large amounts to see an effect.