Deck 37: Soil and Plant Nutrition

Question 1

Which soil mineral is most likely leached away during a hard rain?

A)Na+
B)K+
C)Ca++
D)NO3-
E)H+

Answer 1

D

Question 2

Figure 37.1 shows the results of a study to determine the effect of soil air spaces on plant growth.

Figure 37.1
The data in Figure 37.1 indicate that that the plant

A)grows best at the lower levels of air in the soil.
B)grows about the same in 15% and 20% soil air percent.
C)grows best in soil air levels above 15%.
D)B and C only
E)A, B and C

Answer 2

D

Question 3

In west Texas, cotton has become an important crop in the last several decades. However, in this hot, dry part of the country there is little rainfall, so farmers irrigate their cotton fields. They must also regularly fertilize the cotton fields because the soil is very sandy. Figure 37.2 shows the record of annual productivity (measured in kilograms of cotton per hectare of land) since 1960 in a west Texas cotton field. Use these data to answer the following questions.

Figure 37.2
Based on the information provided above, what is the most likely cause of the decline in productivity?

A)The farmer used the wrong kind of fertilizer.
B)The cotton is developing a resistance to the fertilizer and to irrigation water.
C)Water has accumulated in the soil due to irrigation.
D)The soil water potential has become more negative due to salination.
E)The rate of photosynthesis has declined due to irrigation.

Answer 3

D

Question 4

Which of the following describes the fate of most of the water taken up by a plant?

A)It is used as a solvent.
B)It is used as a hydrogen source in photosynthesis.
C)It is lost during transpiration.
D)It makes cell elongation possible.
E)It is used to keep cells turgid.

Question 5

There are several properties of a soil in which typical plants would grow well. Of the following, which would be the least conducive to plant growth?

A)abundant humus
B)numerous soil organisms
C)compacted soil
D)high porosity
E)high cation exchange capacity

Question 6

In west Texas, cotton has become an important crop in the last several decades. However, in this hot, dry part of the country there is little rainfall, so farmers irrigate their cotton fields. They must also regularly fertilize the cotton fields because the soil is very sandy. Figure 37.2 shows the record of annual productivity (measured in kilograms of cotton per hectare of land) since 1960 in a west Texas cotton field. Use these data to answer the following questions.

Figure 37.2
If you were the county agriculture agent, what would be the best advice you could give the farmer who owns the field under study in Figure 37.2?

A)Plant a variety of cotton that requires less water and can tolerate salinity.
B)Continue to fertilize, but stop irrigating and rely on rainfall.
C)Continue to irrigate, but stop fertilizing and rely on organic nutrients in the soil.
D)Continue to fertilize and irrigate, but add the nitrogen-fixing bacteria Rhizobium to the irrigation water until the productivity increases.
E)Add acid to the soil and increase its cation exchange capabilities so more nutrients are retained in the soil.

Question 7

For this pair of items, choose the option that best describes their relationship. (A)The average size of particles that constitute silt
(B)The average size of particles that constitute clay

A)Item (A)is greater than item (B).
B)Item (A)is less than item (B).
C)Item (A)is exactly or very approximately equal to item (B).
D)Item (A)may stand in more than one of the above relations to item (B).

Question 8

Why does over-watering a plant kill it?

A)Water does not have all the necessary minerals a plant needs to grow.
B)Water neutralizes the pH of the soil.
C)The roots are deprived of oxygen.
D)Water supports the growth of root parasites.
E)Water lowers the water potential of the roots.

Question 9

The N-P-K percentages on a package of fertilizer refer to the

A)total protein content of the three major ingredients of the fertilizer.
B)percentages of manure collected from different types of animals.
C)relative percentages of organic and inorganic nutrients in the fertilizer.
D)percentages of three important mineral nutrients.
E)proportions of three different nitrogen sources.

Question 10

Figure 37.1 shows the results of a study to determine the effect of soil air spaces on plant growth.

Figure 37.1
The best explanation for the shape of the growth response curve in figure 37.1 is that

A)the plant requires air in the soil for photosynthesis.
B)the roots are able to absorb more nitrogen (N2)in high levels of air.
C)most of the decrease in weight at low air levels is due to transpiration from the leaves.
D)increased soil air produces more root mass in the soil but does not affect the top stems and leaves.
E)the roots require oxygen for respiration and growth.

Question 11

A soil well suited for the growth of most plants would have all of the following properties except

A)abundant humus.
B)air spaces.
C)good drainage.
D)high cation exchange capacity.
E)a high pH.

Question 12

What should be added to soil to prevent minerals from leaching away?

A)humus
B)sand
C)mycorrhizae
D)nitrogen
E)silt

Question 13

What soil(s)is(are)the most fertile?

A)humus only
B)loam only
C)silt only
D)clay only
E)both humus and loam

Question 14

If you wanted to increase the cation exchange and water retention capacity of loamy soil, what should you do?

A)Adjust the soil pH to 7.9.
B)Add clay to the soil.
C)Practice no-till agriculture.
D)Add fertilizer containing potassium, calcium and magnesium to the soil.
E)Increase the number of sand particles in the soil.

Question 15

For this pair of items, choose the option that best describes their relationship. (A)The amount of nitrogen in a fertilizer marked "15-10-5"
(B)The amount of nitrogen in a fertilizer marked "15-5-5"

A)Item (A)is greater than item (B).
B)Item (A)is less than item (B).
C)Item (A)is exactly or very approximately equal to item (B).
D)Item (A)may stand in more than one of the above relations to item (B).

Question 16

For this pair of items, choose the option that best describes their relationship. (A)The percent of plant species that form ectomycorrhizae
(B)The percent of plant species that form arbuscular mycorrhizae

A)Item (A)is greater than item (B).
B)Item (A)is less than item (B).
C)Item (A)is exactly or very approximately equal to item (B).
D)Item (A)may stand in more than one of the above relations to item (B).

Question 17

All of the following contributed to the dust bowl in the American southwest during the 1930s except

A)overgrazing by cattle.
B)clear cutting of forest trees.
C)plowing of native grasses.
D)planting of field crops.
E)lack of soil moisture.

Question 18

For this pair of items, choose the option that best describes their relationship. (A)The amount of molybdenum in a gram of dried plant material
(B)The amount of sulfur in a gram of dried plant material

A)Item (A)is greater than item (B).
B)Item (A)is less than item (B).
C)Item (A)is exactly or very approximately equal to item (B).
D)Item (A)may stand in more than one of the above relations to item (B).

Question 19

For this pair of items, choose the option that best describes their relationship. (A)The number of essential macronutrients required by plants
(B)The number of essential micronutrients required by plants

A)Item (A)is greater than item (B).
B)Item (A)is less than item (B).
C)Item (A)is exactly or very approximately equal to item (B).
D)Item (A)may stand in more than one of the above relations to item (B).

Question 20

Figure 37.1 shows the results of a study to determine the effect of soil air spaces on plant growth.

Figure 37.1
The best conclusion from the data in Figure 37.1 is that the plant

A)grows best without air in the soil.
B)grows fastest in 5 to 10% air.
C)grows best at soil air levels above 15%.
D)does not respond differently to different levels of air in the soil.
E)would grow to 24 grams in 40% soil air.

Question 21

Some plants extract and concentrate heavy metals from the soil. A current use for such plants is

A)to help locate suitable sites for toxic waste storage.
B)to concentrate rare metals for medicinal use.
C)to minimize soil erosion in arid lands.
D)nitrogen fixation by symbiotic bacteria in root nodules.
E)photoremediation of polluted sites.

Question 22

What is the major function of sodium in plants?

A)component of lignin-biosynthetic enzymes
B)component of DNA and RNA
C)a component of chlorophyll
D)active in amino acid formation
E)required to regenerate phospophenolpyruvate in C4 and CAM plants

Question 23

Which two elements make up more than 90% of the dry weight of plants?

A)carbon and nitrogen
B)oxygen and hydrogen
C)nitrogen and oxygen
D)oxygen and carbon
E)carbon and potassium

Question 24

A growing plant exhibits chlorosis of the leaves of the entire plant. The chlorosis is probably due to a deficiency of which of the following macronutrients?

A)carbon
B)oxygen
C)nitrogen
D)calcium
E)hydrogen

Question 25

Which element is important in the formation and stability of cell walls?

A)zinc
B)chlorine
C)calcium
D)molybdenum
E)manganese

Question 26

In hydroponic culture, what is the purpose of bubbling air into the solute?

A)to keep dissolved nutrients evenly distributed
B)to provide oxygen to the root cells
C)to inhibit the growth of aerobic algae
D)to inhibit the growth of anaerobic bacteria
E)to provide CO2 for photosynthesis

Question 27

Organic molecules make up what percentage of the dry weight of a plant?

A)6%
B)17%
C)67%
D)81%
E)96%

Question 28

In the 1640s Jan Baptista van Helmont planted a small willow in a pot that contained 90.9 kg of soil. After five years, the plant weighed 76.8 kg, but only 0.06 kg of soil had disappeared from the pot. What did van Helmont conclude from this experiment?

A)80-90% of the tree's mass is the result of C3 photosynthesis.
B)The increase in the mass of the tree was from the water that he added over the five years.
C)Most of the increase in the mass of the tree was due to the uptake of CO2.
D)Soil simply provides physical support for the tree without providing any nutrients.
E)The 0.06 kg of soil was mainly nitrogen.

Question 29

In west Texas, cotton has become an important crop in the last several decades. However, in this hot, dry part of the country there is little rainfall, so farmers irrigate their cotton fields. They must also regularly fertilize the cotton fields because the soil is very sandy. Figure 37.2 shows the record of annual productivity (measured in kilograms of cotton per hectare of land) since 1960 in a west Texas cotton field. Use these data to answer the following questions.

Figure 37.2
A young farmer purchases some land in a relatively arid area and is interested in earning a reasonable profit for many years. Which of the following strategies would best allow such a goal to be achieved?

A)establishing an extensive irrigation system
B)using plenty of the best fertilizers
C)finding a way to sell all parts of crop plants
D)selecting crops adapted to arid areas
E)converting hillsides into fields

Question 30

Which of the following is of least concern to a researcher in a mineral nutrition experiment?

A)purity of the chemicals used to make the nutrient solutions
B)purity of the water used to make the nutrient solutions
C)chemical inertness of the container used to make and store the nutrient solutions
D)ability of a laboratory balance to weigh very small quantities of chemicals
E)medium in which the test seedlings were grown

Question 31

Most of the dry weight of a plant is the result of uptake of

A)water and minerals through root hairs.
B)water and minerals through mycorrhizae.
C)CO2 through stoma.
D)CO2 and O2 through stomata in leaves.
E)carbohydrates in the root hairs and concentration in the root cortex.

Question 32

You are conducting an experiment on plant growth. You take a plant fresh from the soil that weighs 5 kg. Then you dry the plant overnight and determine the dry weight to be 1 kg. Of this dry weight, how much would you expect to be made up of organic molecules?

A)1 gram
B)4 grams
C)40 grams
D)960 grams
E)1 kg

Question 33

The bulk of a plant's dry weight is derived from

A)soil minerals.
B)CO2.
C)the hydrogen from H₂O.
D)the oxygen from H₂O.
E)the uptake of organic nutrients from the soil.

Question 34

Which of the following essential nutrients plays an essential role in the opening and closing of the stomatal aperture?

A)Fe
B)Bo
C)Mg
D)H
E)K

Question 35

In west Texas, cotton has become an important crop in the last several decades. However, in this hot, dry part of the country there is little rainfall, so farmers irrigate their cotton fields. They must also regularly fertilize the cotton fields because the soil is very sandy. Figure 37.2 shows the record of annual productivity (measured in kilograms of cotton per hectare of land) since 1960 in a west Texas cotton field. Use these data to answer the following questions.

Figure 37.2
A farming commitment that embraces a variety of methods that are conservation-minded, environmentally safe, and profitable is called

A)hydroponics.
B)nitrogen fixation.
C)responsible irrigation.
D)genetic engineering.
E)sustainable agriculture.

Question 36

What is the major function of nitrogen in plants?

A)component of lignin-biosynthetic enzymes
B)component of DNA and RNA
C)a component of chlorophyll
D)active in amino acid formation
E)required to regenerate phospophenolpyruvate in C4 and CAM plants

Question 37

When performing a mineral nutrition experiment, researchers use water from a glass still. Why is it not a good idea to use regular distilled water from a stainless steel still?

A)With a steel still, lime deposits from hard water will build up too quickly.
B)Salts in the water corrode steel more quickly than glass.
C)Metal ions dissolving off the steel may serve as micronutrients.
D)A glass still allows the distillation process to be observed.
E)There is no difference; both kinds of stills produce distilled water.

Question 38

What are the three main elements on which plant growth and development depend?

A)nitrogen; carbon; oxygen
B)potassium; carbon; oxygen
C)oxygen; carbon; hydrogen
D)phosphorus; nitrogen; oxygen
E)sulfur; nitrogen; phosphorus

Question 39

Which of the following elements is incorrectly paired with its function in a plant?

A)nitrogen component of nucleic acids, proteins, hormones, coenzymes
B)magnesium component of chlorophyll; activates many enzymes
C)phosphorus component of nucleic acids, phospholipids, ATP, several coenzymes
D)potassium cofactor functional in protein synthesis; osmosis; operation of stomata
E)sulfur component of DNA; activates some enzymes

Question 40

What is the major function of magnesium in plants?

A)component of lignin-biosynthetic enzymes
B)component of DNA and RNA
C)a component of chlorophyll
D)active in amino acid formation
E)required to regenerate phospophenolpyruvate in C4 and CAM plants

Question 41

In what way do nitrogen compounds differ from other minerals needed by plants?

A)Only nitrogen can be lost from the soil.
B)Only nitrogen requires the action of bacteria to be made available to plants.
C)Only nitrogen is needed for protein synthesis.
D)Only nitrogen is held by cation exchange capacity in the soil.
E)Only nitrogen can be absorbed by root hairs.

Question 42

Reddish-purple coloring of leaves, especially along the margins of young leaves, is a typical symptom of deficiency of which element?

A)C
B)M++
C)N
D)P
E)K+

Question 43

Why is nitrogen fixation such an important process?

A)Nitrogen fixation can only be done by certain prokaryotes.
B)Fixed nitrogen is most often the limiting factor in plant growth.
C)Nitrogen fixation is very expensive in terms of metabolic energy.
D)Nitrogen fixers are sometimes symbiotic with legumes.
E)Nitrogen-fixing capacity can be genetically engineered.

Question 44

In a root nodule, the gene coding for nitrogenase

A)is inactivated by leghemoglobin.
B)is absent in active bacteroids.
C)is found in the cells of the pericycle.
D)protects the nodule from nitrogen.
E)is part of the Rhizobium chromosome.

Question 45

Nitrogen fixation is a process that

A)recycles nitrogen compounds from dead and decaying materials.
B)converts ammonia to nitrate.
C)releases nitrate from the rock substrate.
D)converts nitrogen gas into ammonia.
E)A and B

Question 46

What is the function of a root nodule's leghemoglobin?

A)extract macronutrients from the soil.
B)regulate the supply of oxygen to Rhizobium.
C)promote ion exchange in the soil.
D)form a mutualistic relationship with insects.
E)supply the legume with fixed nitrogen.

Question 47

The enzyme complex nitrogenase catalyzes the reaction that reduces atmospheric nitrogen to

A)N2.
B)NH3.
C)NO2.
D)NO+.
E)NO-.

Question 48

Among important crop plants, nitrogen-fixing root nodules are most commonly an attribute of

A)corn.
B)legumes.
C)wheat.
D)members of the potato family.
E)cabbage and other members of the brassica family.

Question 49

What is meant by the term chlorosis?

A)the uptake of the micronutrient chlorine by a plant
B)the formation of chlorophyll within the thylakoid membranes of a plant
C)the yellowing of leaves due to decreased chlorophyll production
D)a contamination of glassware in hydroponic culture
E)release of negatively charged minerals such as chloride from clay particles in soil

Question 50

Which of the following best describes the general role of micronutrients in plants?

A)They are cofactors in enzymatic reactions.
B)They are necessary for essential regulatory functions.
C)They prevent chlorosis.
D)They are components of nucleic acids.
E)They are necessary for the formation of cell walls.

Question 51

Which of the following is a True statement about nitrogen fixation in root nodules?

A)The plant contributes the nitrogenase enzyme.
B)The process is relatively inexpensive in terms of ATP costs.
C)Leghemoglobin helps maintain a low O2 concentration within the nodule.
D)The process tends to deplete nitrogen compounds in the soil.
E)The bacteria of the nodule are autotrophic.

Question 52

Which of the following is not a function of rhizobacteria?

A)produce hormones that stimulate plant growth
B)produce antibiotics that protect roots from disease
C)absorb toxic metals
D)carry out nitrogen fixation
E)supply growing roots with glucose

Question 53

Iron deficiency is often indicated by yellowing in newly formed leaves. This suggests that iron

A)is a relatively immobile nutrient in plants.
B)is tied up in formed chlorophyll molecules.
C)is concentrated in the xylem of older leaves.
D)is concentrated in older leaves.
E)is found in leghemoglobin and reduces the amount available to new plant parts.

Question 54

Which of the following is not True of micronutrients in plants?

A)They are the elements required in relatively small amounts.
B)They are required for a plant to grow from a seed and complete its life cycle.
C)They generally help in catalytic functions in the plant.
D)They are the essential elements of small size and molecular weight.
E)Overdoses of them can be toxic.

Question 55

The most efficient way to increase essential amino acids in crop plants for human consumption is to

A)breed for higher yield of deficient amino acids.
B)increase the amount of fertilizer used on fields.
C)use 20-20-20 fertilizer instead of 20-5-5 fertilizer.
D)engineer nitrogen-fixing nodules into crop plants lacking them.
E)increase irrigation of nitrogen-fixing crops.

Question 56

If an African violet has chlorosis, which of the following elements might be a useful addition to the soil?

A)chlorine
B)molybdenum
C)copper
D)iodine
E)magnesium

Question 57

You are weeding your garden when you accidentally expose some roots. You notice swellings (root nodules)on the roots. Most likely your plant

A)suffers from a mineral deficiency.
B)is infected with a parasite.
C)is benefiting from a mutualistic bacterium.
D)is developing offshoots from the root.
E)contains developing insect pupa.

Question 58

A woodlot was sprayed with a fungicide. What would be the most serious effect of such spraying?

A)a decrease in food for animals that eat mushrooms
B)an increase in rates of wood decay
C)a decrease in tree growth due to the death of mycorrhizae
D)an increase in the number of decomposing bacteria
E)A and B

Question 59

Most crop plants acquire their nitrogen mainly in the form of

A)NH3.
B)N2.
C)CN2H2.
D)NO3..
E)amino acids absorbed from the soil.

Question 60

If a plant is infected with Rhizobium, what is the probable effect on the plant?

A)It gets chlorosis.
B)It dies.
C)It is supplied with phosphate from the soil.
D)It probably will grow faster
E)It becomes flaccid due to the loss of water from the roots

Question 61

Young seedlings rarely show mineral deficiency symptoms because their mineral requirements are met largely by minerals released from stored reserves in the seed itself.

Question 62

A mineral deficiency is likely to affect older leaves more than younger leaves if

A)the mineral is a micronutrient.
B)the mineral is very mobile within the plant.
C)the mineral is required for chlorophyll synthesis.
D)the mineral is a macronutrient.
E)the older leaves are in direct sunlight.

Question 63

Macronutrients, elements required in relatively large amounts, typically have catalytic functions as cofactors of enzymes.

Question 64

Plant roots excrete substances that bind the soil particles and raise the soil pH.

Question 65

Two groups of tomatoes were grown under laboratory conditions, one with humus added to the soil and one a control without the humus. The leaves of the plants grown without humus were yellowish (less green)compared with those of the plants grown in humus-enriched soil. The best explanation for this difference is that

A)the healthy plants used the food in the decomposing leaves of the humus for energy to make chlorophyll.
B)the humus made the soil more loosely packed, so water penetrated more easily to the roots.
C)the humus contained minerals such as magnesium and iron, needed for the synthesis of chlorophyll.
D)chlorophyll synthesis.
E)the healthy plants absorbed chlorophyll from the humus.

Question 66

Dwarf mistletoe grows on many pine trees in the Rockies. Although the mistletoe is green, it is probably not sufficiently active in photosynthesis to produce all the sugar it needs. The mistletoe also produces haustoria. Thus, dwarf mistletoe growing on pine trees is best classified as

A)an epiphyte.
B)a nitrogen-fixing plant.
C)a carnivorous plant.
D)a symbiotic plant.
E)a parasite.

Question 67

Phytoremediation is a biotechnology that uses the ability of some plants to extract soil pollutants and concentrate them in portions of the plant that can be easily removed for safe disposal.

Question 68

Plants acquire most of their nitrogen in the form of N2 that they obtain from rhizobacteria.

Question 69

Some of the problems associated with intensive irrigation include all but

A)mineral runoff.
B)overfertilization.
C)land subsidence.
D)aquifer depletion.
E)soil salinization.

Question 70

The rhizosphere would best be described as

A)legume root swellings that are involved in nitrogen fixation.
B)the part of the topsoil that supplies carbohydrates to plants.
C)soil that is bound to roots and differs from the surrounding soil in containing many more microbes.
D)the spherical soil horizon in which roots typically grow.
E)all of the living organisms that inhabit the soil.

Question 71

Which of the following is a primary difference between ectomycorrhizae and endomycorrhizae?

A)Endomycorrhizae have thicker, shorter hyphae than ectomycorrhizae.
B)Endomycorrhizae, but not ectomycorrhizae, form a dense sheath over the surface of the root.
C)Ectomycorrhizae do not penetrate root cells, whereas endomycorrhizae grow into invaginations of the root cell membranes.
D)Ectomycorrhizae are found in woody plant species; about 85% of plant families form ectomycorrhizae.
E)There are no significant differences between ectomycorrhizae and endomycorrhizae.

Question 72

The earliest vascular plants on land had underground stems (rhizomes)but no roots. Water and mineral nutrients were most likely obtained by

A)absorption by hairs and trichomes.
B)diffusion through stomata.
C)absorption by mycorrhizae.
D)osmosis through the root hairs.
E)diffusion across the cuticle of the rhizome.

Question 73

Most of the mass of organic material of a plant comes from

A)water.
B)carbon dioxide.
C)soil minerals.
D)atmospheric oxygen.
E)nitrogen.

Question 74

What are epiphytes?

A)aerial vines common in tropical regions
B)haustoria used for anchoring to host plants and obtaining xylem sap
C)plants that live in poor soil and digest insects to obtain nitrogen
D)plants that grow on other plants but do not obtain nutrients from their hosts
E)plants that have a symbiotic relationship with fungi

Question 75

Micronutrients are needed in very small amounts because

A)most of them are mobile in the plant.
B)most serve mainly as cofactors of enzymes.
C)most are supplied in large enough quantities in seeds.
D)they play only a minor role in the growth and health of the plant.
E)only the most actively growing regions of the plants require micronutrients.

Question 76

Carnivorous plants have evolved mechanisms that trap and digest small animals. The products of this digestion are used to supplement the plant's supply of

A)energy.
B)carbohydrates.
C)lipids and steroids.
D)minerals.
E)water.

Question 77

What is the mutualistic association between roots and fungi called?

A)nitrogen fixation
B)Rhizobium infection
C)mycorrhizae
D)parasitism
E)root hair enhancement

Question 78

The fungal hyphae of both ectomycorrhizae and arbuscular mycorrhizae absorb water and minerals, which they supply to their plant hosts.

Question 79

Deficiency of a mobile nutrient usually affects older organs more than younger ones.

Question 80

Hyphae form a covering over roots. Altogether, these hyphae create a large surface area that helps to do which of the following?

A)aid in absorbing minerals and ions
B)maintain cell shape
C)increase cellular respiration
D)anchor a plant
E)protect the roots from ultraviolet light