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Problem 1
Fill in the blanks in this concept map to help you tie together key concepts concerning transport in plants.
Problem 2
Plants require the smallest amount of which of the following nutrients?
a. Oxygen
b. Phosphorus
c. Carbon
d. Iron
Problem 3
Which of the following activities of soil bacteria does not contribute to creating usable nitrogen supplies for plant use?
a. The fixation of atmospheric nitrogen
b. The conversion of ammonium ions to nitrate ions
c. The decomposition of dead animals
d. The assembly of amino acids into proteins
Problem 4
By trapping insects, carnivorous plants obtain ___________, which they need ___________ . (Choose the best answer.)
a. Water ... because they live in dry soil
b. Nitrogen ... to make sugar
c. Phosphorus ... to make protein
d. Nitrogen ... to make protein
Problem 5
An advantage of using fertilizers derived from natural sources is that these fertilizers
a. Have different minerals than artificial fertilizers.
b. Are retained in soil longer.
c. Are more soluble in water.
d. Are more concentrated.
- Explain how guard cells limit water loss from a plant on a hot, dry day. How can this be harmful to the plant?
Problem 6
Problem 7
Transpiration is fastest when humidity is low and temperature is high, but in some plants it seems to increase in response to light as well. During one 12-hour period when cloud cover and light intensity varied frequently, a scientist studying a certain crop plant recorded the data in the table (top right). (The transpiration rates are grams of water per square meter of leaf area per hour.)
Do these data support the hypothesis that the plants transpire more when the light is more intense?
If so, is the effect independent of temperature and humidity?
Explain your answer. (Hint: Look for overall trends in each column, and then compare pairs of data within each column and between columns.)
- Certain types of fungi cause diseases in plants. There are a variety of antifungal sprays that can be used to control this problem. Some gardeners constantly spray their plants with fungicides, even when no signs of disease are evident. How might this be disadvantageous to the plant?
Problem 8
- If the apples you buy are labeled 'organic,' does that tell you anything about how they were grown? About the nutritional content of the apples?
Problem 9
Problem 10
Acid rain contains an excess of hydrogen ions (H+). One effect of acid rain is to deplete the soil of plant nutrients such as calcium (Ca²⁺), potassium (K⁺), and magnesium (Mg²⁺).
Offer a hypothesis to explain why acid rain washes these nutrients from the soil.
How might you test your hypothesis?
- Agriculture is by far the biggest user of water in arid western states, including Colorado, Arizona, and California. The populations of these states are growing, and there is an ongoing conflict between cities and farm regions over water. To ensure water supplies for urban growth, cities are purchasing water rights from farmers. This is often the least expensive way for a city to obtain more water, and some farmers can make more money selling water than growing crops. Discuss the possible consequences of this trend. Is this the best way to allocate water for all concerned? Why or why not?
Problem 11
Problem 12
One of the most important properties of proper scientific investigations is their repeatability. Yet, as discussed in Module 32.11, studies that compare the nutritional content of conventional and organic produce sometimes produce contradictory results. Name some possible confounding factors that can account for such uneven results.