Deck 36: Plant Nutrition

Question 1

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

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

Answer 1

B

Question 2

A major function of magnesium in plants is to ________.

A) regenerate phosphoenolpyruvate in C4 and CAM plants
B) be a component of DNA and RNA
C) be a component of chlorophyll
D) be active in amino acid formation

Answer 2

C

Question 3

Which of the following elements correctly pairs an essential element in plants with its function?

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

Answer 3

A

Question 4

Two groups of tomatoes were grown under laboratory conditions, one with humus added to the soil and one a control without humus. The leaves of the plants grown without humus were yellowish (less green) compared with those of the plants grown in the 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) the heat released by the decomposing leaves of the humus caused more rapid growth and chlorophyll synthesis
E) the plants absorbed essential macronutrients necessary for chlorophyll synthesis from the humus

Question 5

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

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

Question 6

Which of the following elements is required for the stability of cell walls?

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

Question 7

Clay in soils represents a trade-off in nutrient availability, such that ________.

A) anions are less likely to leach out of soil but are difficult for plants to extract
B) cations are less likely to leach out of soil but are difficult for plants to extract
C) nitrogen levels are exceptionally high, but much of the nitrogen leaches away
D) oxygen levels are exceptionally high, but much of the nitrogen leaches away

Question 8

Stunted growth and leaf necrosis, especially in young plants, is a typical symptom of deficiency of which element?

A) C
B) Mg2+
C) N
D) P
E) K+

Question 9

Which of the following statements about essential nutrients are TRUE? Essential nutrients ________.
I) are necessary for plant growth and reproduction
II) are required for a specific structure or metabolic function
III) cannot be synthesized by a plant
IV) are produced by symbiotic bacteria

A) I and IV
B) II, III, and IV
C) I, II, and III
D) I, II, III, and IV

Question 10

The highest amount of oxygen will be found in soils containing large amounts of ________.

A) clay
B) sand
C) gravel
D) silt

Question 11

Which criteria allow biologists to divide chemicals into macronutrients and micronutrients?

A) molecular weight of the element or compound
B) the quantities of each required by plants
C) how they are used in metabolism
D) whether or not they are essential for plant growth

Question 12

Most of the dry mass of a plant is derived from ________.

A) NO3- and CO2
B) K+ and CO2
C) PO4 and K+
D) H2O and K+
E) H2O and CO2

Question 13

How does phosphorus normally enter ecosystems?

A) cellular respiration
B) photosynthesis
C) rock weathering
D) burning of fossil fuels
E) atmospheric phosphorous gas

Question 14

The NPK 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 15

Which of the following experiments is the best way to determine if an element is essential for plant growth?

A) Measure the amount of the element stored in plant tissues.
B) Grow plants in soil deficient in the element and note whether or not the plants are healthy.
C) Measure the amount of the element in the soil after plant growth.
D) Grow plants using hydroponics with and without the element and measure plant growth and health.
E) Measure the weight of the plant and soil before and after plant growth.

Question 16

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 17

You are conducting an experiment on plant growth. You take a plant fresh from the soil that weighs 5 kilograms (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 oxygen, carbon, and hydrogen?

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

Question 18

Which elements are most often the limiting nutrients for plant growth?

A) nitrogen, potassium, phosphorus
B) nitrogen, oxygen, hydrogen
C) carbon, sodium, chlorine
D) carbon, nitrogen, oxygen
E) carbon, potassium, sodium

Question 19

In plants, micronutrients ________.

A) are required in relatively large amounts
B) are required only during germination of seeds
C) generally help in catalytic functions in the plant
D) are required only during flowering

Question 20

To understand the role of zinc in plant growth and development, you grow a tomato plant using hydroponics. Which plant organs do you expect to have developmental defects if you provide the plant with a solution devoid of zinc?

A) leaf development only
B) stem development only
C) aboveground development only
D) belowground development only
E) All organs will be affected.

Question 21

Which of the following plant structures shares the most common features and functions with a fungal hyphae?

A) stomata
B) vascular cambium
C) lenticels
D) root hairs
E) fibrous root systems

Question 22

The micronutrient iron is abundant in soil but often unavailable to plants due to insolubility. Knowing that the reaction Fe(OH)3 + 3 H+ ↔ Fe3+ + 3 H2O occurs, and assuming all soil samples have the same total amount of iron, which type of soil would you predict to have the highest amount of soluble iron?

A) neutral
B) acidic
C) alkaline
D) The amount of iron in soil does not depend on pH.

Question 23

The most efficient way to increase essential amino acids in crop plants for human consumption would be to ________.

A) select for higher yield of the desired 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 24

Agricultural lands frequently require nutrient augmentation because ________.

A) nitrogen-fixing bacteria are not as plentiful in agricultural soils because of the use of pesticides
B) nutrients within crop plants are not cycled back to the soil on lands where they are harvested
C) land that is available for agriculture tends to be nutrient-poor
D) grains raised for feeding livestock must be fortified and thus require additional nutrients
E) irrigation of agricultural land reduces oxygen availability in soils and inhibits the decomposition of organic matter

Question 25

What soil composition would be best for availability of nutrients, water, and root development?

A) equal amounts of sand, clay, and humus
B) higher proportion of humus, lower amounts of clay and sand
C) higher proportion of clay, lower amounts of humus and sand
D) higher proportion of sand, lower amount of humus and clay

Question 26

Why are anionic nutrients generally mobile in soils, and thus easily leached, while cationic nutrients are relatively immobile?

A) Anions readily form crystals while cations do not.
B) Cations interact with clay particles and organic materials.
C) Cations are more readily taken up by plant roots.
D) Anions are repelled from the surfaces of living roots.

Question 27

If you wanted to increase the cation exchange and water retention capacity of loamy soil, you should ________.

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 28

Mycorrhizae enhance plant nutrition mainly by ________.

A) absorbing water and minerals through the fungal hyphae
B) providing sugar to root cells, which have no chloroplasts
C) converting atmospheric nitrogen to ammonia
D) enabling the roots to parasitize neighboring plants
E) stimulating the development of root hairs

Question 29

After mutagenesis and screening, you have found a mutant that is able to grow in soil with high salt content. Chemical analysis showed that this plant has a decreased amount of Na+ throughout the entire plant relative to normal plants. What kind of mutation do you predict this plant contains?

A) mutation affecting plasma membrane sodium channels
B) mutation affecting metallothioneins
C) mutation affecting tonoplast sodium channels
D) mutation affecting tonoplast antiporters

Question 30

Which of the following contributed to the dust bowl in the American southwest during the 1930s?
I) overgrazing by cattle
II) clear-cutting of forest trees
III) plowing of native grasses
IV) lack of soil moisture

A) I and II
B) II, III, and IV
C) I, III, and IV
D) I, II, III, IV

Question 31

Which of the following would be the most effective strategy to remove toxic heavy metals from a soil?

A) heavy irrigation to leach out the heavy metals
B) application of fertilizers to compete with heavy-metal uptake
C) application of sulfur to lower the soil pH and precipitate the heavy metals
D) adding plant species that have the ability to take up and accumulate heavy metals
E) inoculating soil with mycorrhizae to avoid heavy-metal uptake

Question 32

What is the function of proton pumps localized in the plant plasma membrane?

A) to facilitate diffusion of ions
B) to transfer phosphorus groups from ATP to proteins
C) to transfer metal ions across the plasma membrane
D) to transfer anions across the plasma membrane
E) to create a membrane potential

Question 33

Which of the following are problems associated with intensive irrigation?
I) mineral runoff
II) overfertilization
III) aquifer depletion
IV) soil salinization

A) only I and II
B) only II and IV
C) only I, III, and IV
D) only III and IV
E) I, II, III, and IV

Question 34

Which of the following would inhibit the growth of most plants?

A) abundant humus
B) air spaces
C) good drainage
D) high cation exchange capacity
E) a pH of 8.5

Question 35

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 the farmer to achieve such a goal in a sustainable way?

A) establishing an extensive irrigation system
B) using plenty of the best fertilizers
C) growing high value crops that require rich, moist soil
D) selecting crops adapted to arid areas
E) converting hillsides into fields

Question 36

Root hairs are most important to a plant because they ________.

A) anchor a plant in the soil
B) store starches
C) increase the surface area for absorption
D) provide a habitat for nitrogen-fixing bacteria
E) contain xylem tissue

Question 37

The irt1 gene is responsible for most of the iron uptake activity in roots (Vert et al., Plant Cell 14 [2002]: 1223-33). To determine the specificity of the irt1 transporter in Arabidopsis plants, researchers measured the concentration of manganese, zinc, copper, and cobalt contained in wild-type and irt1-1 mutant plants. What conclusions about irt1 specificity can you draw from the data in the accompanying figure?

A) Under iron-deficient conditions, irt1 is highly specific for iron.
B) Under iron-deficient conditions, irt1 is important for the transport of iron and copper.
C) irt1 is important for the transport of iron and copper independent of iron concentration.
D) Under iron-deficient conditions, irt1 is necessary for the transport of zinc, manganese, and cobalt.
E) irt1 participates in the transport of iron, zinc, manganese, and cobalt independent of iron concentration.

Question 38

Why do plants use cotransporters instead of ion channels to transfer anions into cells?

A) Cotransporters are able to transfer anions against the membrane potential gradient, but ion channels cannot.
B) Cotransporters can transfer ions across cell membranes, but ion channels cannot transport ions across cell membranes.
C) Cotransporters are able to transfer anions against the proton gradient, but ion channels cannot.
D) Anions are too bulky to be transported by ion channels.

Question 39

Which of the following soil minerals is most likely leached away during a hard rain in high clay soil?

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

Question 40

Pine seedlings grown in sterile potting soil grow much slower than seedlings grown in soil from the area where the seeds were collected. This is most likely because ________.

A) sterilized soil kills the root hairs as they emerge from the seedling
B) the normal symbiotic fungi are not present in the sterilized soil
C) sterilization removes essential nutrients from the soil
D) water and mineral uptake are slower when mycorrhizae are present

Question 41

Which of the following statements about nitrogen fixation in root nodules is correct?

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

Question 42

After mutagenesis, the nitrogen-fixing bacterium Sinorhizobium meliloti could no longer colonize Medicago truncatula plants. This inability to colonize was due to the absence of recognition by the host plant. Which of the following genes is most likely the site of the mutation in these bacteria?

A) nitrogenase
B) flavonoid-synthesizing enzyme
C) Nod factors
D) leghemoglobin
E) peptidoglycans of the bacterial cell wall

Question 43

What kind of climate is most often associated with epiphytic plants?

A) warm
B) humid
C) sunny
D) freezing

Question 44

Nitrogen fixation is a process that ________.

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

Question 45

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

A) can be lost from the soil
B) can be provided by symbiotic bacteria
C) is needed for protein synthesis
D) is held by cation exchange capacity in the soil
E) can be absorbed by root hairs

Question 46

Epiphytes are ________.

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 47

What is a typical habitat for carnivorous plants?

A) wet areas with high salinity
B) wet areas with high levels of humus
C) wet areas with low decomposition rates
D) dry areas with low levels of available oxygen
E) dry areas with high levels of peat

Question 48

Which of the following, if used as a fertilizer, would be most immediately available for plant uptake?

A) NH3
B) N2
C) CN2H2
D) NO3-
E) amino acids

Question 49

A rootless, green plant is found growing on the branches and trunks of rain forest trees but lacks any apparent adaptation for collecting rainwater. This plant is most likely ________.

A) an epiphyte
B) a nitrogen-fixing plant
C) a carnivorous plant
D) a mutualistic plant
E) a parasitic plant

Question 50

Why is nitrogen fixation an essential process?

A) Nitrogen fixation can only be done by certain prokaryotes.
B) Fixed nitrogen is 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 51

While hiking in a forest, you notice an unusual plant growing on the branches of a tree. What will help you to determine if this plant is epiphytic or parasitic?

A) If the plant is green, it is epiphytic; if not, then it is parasitic.
B) The root of an epiphytic plant will be in the soil, but a parasitic plant will grow from the trunk of a tree.
C) The roots of a parasitic plant will penetrate under the bark into the tree tissues, and the roots of an epiphytic plant will not.
D) The epiphytic plant will have large water-collecting leaves, and the parasitic plant will not.

Question 52

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) nitrogen and other minerals
E) water

Question 53

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 root hair
D) protects the nodule from nitrogen
E) is part of the Rhizobium genome

Question 54

What is the correct sequence of steps during infection of plants by nitrogen-fixing bacteria?

A) Rhizobia release Nod factors; roots release flavonoids; rhizobia proliferate inside of root hair; infection thread grows into the root cortex; nodule forms.
B) Rhizobia release flavonoids; roots release Nod factors; rhizobia proliferate inside of root hair; infection thread grows into the root cortex; nodule forms.
C) Roots release flavonoids; rhizobia release Nod factors; rhizobia proliferate inside of root hair; nodule forms; infection thread grows into the root cortex.
D) Roots release flavonoids; rhizobia release Nod factors; rhizobia proliferate inside of root hair; infection thread grows into the root cortex; nodule forms.
E) Nodule forms; infection thread grows into the root cortex; rhizobia proliferate inside of root hair; rhizobia release flavonoids and Nod factors.