While fishing, a biology student makes the following observations:
1) Water spiders appear to be able walk on the surface of the water.
2) Flat rocks may be made to skip across the water.
Which of the following properties of water can explain these observations?
A) Water is an excellent solvent.
B) Water molecules create spheres of hydration around solute molecules.
C) Water molecules are cohesive.
D) Water molecules are often associated via hydrogen bonds.
E) both choices C and D
E) both choices C and D
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Which of the following is/are true about endotoxins?
A. Lipid A is the toxic portion of the molecule. B. The toxic effects depend on the bacteria from which it came. C. The lipid A is immunogenic. D. They are proteins. E. The toxic effects depend on the bacteria from which it came AND they are proteins.
According to the cohesion-tension mechanism of water transport, cohesion occurs because
a. waxy coatings on insides of xylem keep water molecules together in the xylem. b. evaporation removes water from the leaves. c. water molecules tend to form hydrogen bonds with each other. d. water is pushed into the xylem by bulk flow. e. water is pushed into the xylem by phloem pressure.
As you look through the microscope, you observe a liver cell just beginning to enter mitosis. Identify the steps of mitosis that are listed in correct order.
A. prophase, B. metaphase, C. anaphase, D. telophase E. all of the above
Which of the following substances is mismatched with its role?
a. Most B vitamins - coenzymes b. Vitamin A - incorporated into visual pigments c. Iron - component of thyroid hormones d. Vitamin D - aids in calcium absorption e. Phosphorus - bone formation, nucleotide synthesis