Which of the following is true regarding the use of osmotic pressure as an antimicrobial agent?
A. Exposing organisms to the air on a benchtop so they completely dry out is an example of using osmotic pressure as a means of microbial control.
B. Exposing a microbe to a hypertonic environment draws water out of the cell, causing plasmolysis.
C. Salts and sugars external to a microbe create a hypotonic environment, which causes lysis of the cell.
D. Salt is an effective solute to create an osmotic pressure gradient outside of a cell; however, the use of sugar, such as in jams and jellies, works via a different mechanism.
Answer: B
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The function of pits in the walls of tracheids is
A. allowing the passage of water.B. stopping backflow of water. C. secretion of resin. D. sealing off air bubbles. E. allowing the escape of air.
Which statement is true?
a. High concentrations of ATP inhibit the formation of more ATP. b. The ATP concentration in cells actually decreases at first when cells need large supplies of energy. c. The activity of many different enzymes influences the supply of ATP in cells. d. Cells constantly adjust their metabolic reactions to provide energy whenever it is needed. e. All of these are true.
During the 1960s, a group of scientists in the northeastern United States conducted an experiment at Hubbard Brook, New Hampshire. A 38-acre watershed was completely deforested and the runoff (water flow) monitored for several years. It was compared to an adjacent watershed that was left untouched. The scientists collected data during those years and found
A. no difference in the amount of runoff from the two areas. B. an insignificant difference in the amount of nitrogen from the two areas. C. a tremendous increase in the total amount of runoff from Hubbard Brook although the loss of nitrogen was fairly consistent in both areas. D. a tremendous increase in the amount of runoff and nitrogen release from Hubbard Brook compared to the control.
Essential plant nutrients include carbon, potassium, calcium, and nitrogen.
Answer the following statement true (T) or false (F)