Biology, Eighth Edition (Raven)

Chapter 39: Plant Nutrition and Soils

Post Test

1
Why does a low pH soil cause problems for many plants? (p. 776)
A)The low pH decreases the amount of H+ ions for the plant to use.
B)Decreased pH causes ions to become soluble and thus available for the roots to absorb.
C)The pH of a soil dissolves cell membranes, causing them to fall apart.
D)All of the above are reasons for plant growth problems.
E)None of the above are reasons why a low pH interferes with plant growth.
2
Hydroponics is a method of plant propagation that can ensure proper micronutrient delivery by immersing the roots in water. What must be especially watched to ensure health using this technique? (p. 778)
A)Plants won't get enough light.
B)Pollination can't occur using hydroponics.
C)Aeration of roots can be compromised if immersed for too long.
D)Insect pollination can never happen in a hydroponic environment.
E)Leaves can get infected with mold because of the high humidity.
3
The nitrogen-fixing bacterium Rhizobium requires assistance from a plant (usually a legume) in order to grow. Much of it is in the form of ATP derived from organic molecules provided by the plant. Why is so much energy required by Rhizobium during its mutualistic behavior? (p. 779)
A)In the soil are many competitors. The energy Rhizobium absorbs increases its temperature, interfering with the growth of its antagonists.
B)Rhizobium has no immune system (like most bacteria). Thus, the plant provides protection.
C)Plants provide oxygen to Rhizobium in order to make its cellular respiration more efficient.
D)Plants secrete nod factors to the bacterium during periods when its ATP levels are high. These stimulate the bacterium to form nodules.
E)The triple-bond in N2 gas is hard to break. Energy from the plant makes this possible as it donates ATP.
4
In experiments where plants are subjected to higher levels of CO2, what else must be considered in order to maximize growth? (p. 783)
A)There must be less oxygen in the atmosphere.
B)More stomata must be created to allow enough CO2 to enter plants to make a difference.
C)Cellular reserves of sugar must increase to make enough RuBP to allow more fixation of CO2.
D)Plants must have larger leaves to be able to access the higher levels of CO2 in the air.
E)Access to amino-generating elements must be increased as plants are not made of hydrocarbons and oxygen alone.
5
One concern about using phytoremediation to clean up a toxic area is that (p. 785)
A)the plants will become radioactive.
B)soil water will increase in its toxicity due to the plant metabolic activity on the pollution.
C)phytoaccumulation means that much of the material will diffuse back into the soil.
D)phytovolatilization may distribute the substance over larger areas.
E)substances used for phytoremediation may end up in the human food chain.
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