Deck 32: Plant Nutrition and Transport

Question 1

Which sequence of structures through which water passes into a root is correct?

A) guard cell, endodermis, cortex, xylem
B) root hair, cortex, xylem, endodermis
C) epidermis, cortex, endodermis, xylem
D) root hair, xylem, endodermis, phloem

Answer 1

C

Question 2

Under which weather condition would transpiration be most rapid?

A) hot, humid weather
B) cold, humid weather
C) hot, dry weather
D) windy, wet weather

Answer 2

C

Question 3

How do mineral ions get into the xylem cells of a plant root by way of the intracellular route?

A) They travel between root cells to the xylem and then enter a xylem vessel.
B) They are actively taken in to the xylem of root hairs.
C) They are taken up by root hair cells and transferred from cell to cell via plasmodesmata.
D) They move in solution through cell walls of the endodermis.

Answer 3

C

Question 4

Generally speaking, fluids in plants are

A) pushed through phloem with a pressure gradient and pulled through xylem.
B) pushed through xylem with a pressure gradient and pulled through phloem.
C) pulled through both xylem and phloem.
D) actively pumped throughout the plant.

Question 5

A hot, dry summer will reduce crop yields in part because

A) carbon dioxide release is reduced by the stomata closing to prevent excessive water loss.
B) carbon dioxide uptake is reduced by the stomata closing to prevent excessive water loss.
C) oxygen uptake is reduced by the stomata closing to prevent excessive water loss.

Question 6

If a plant is kept in the dark

A) the stomata continue their daily rhythm of opening and closing.
B) the stomata will remain closed the entire time that the plant is in the dark.
C) the stomata will remain open the entire time that the plant is in the dark.
D) the guard cells will open as water is added.

Question 7

Where do plants get most of their mass?

A) from nitrogen in the atmosphere
B) from carbon dioxide in the atmosphere
C) from water, as van Helmont predicted
D) from organic molecules taken up from the soil

Question 8

________ increase the surface area of roots.

A) Plasmodesmata
B) Cell walls
C) Casparian strips
D) Root hairs

Question 9

The water pressure gradient in phloem tubes is formed by the

A) leaves being higher than the roots, which means that gravity creates pressure.
B) diffusion of water from one sieve-tube cell to the next.
C) loading of sugars into phloem at sources and removal of sugars at sinks.
D) active transport of water from sugar sources to sugar sinks.

Question 10

What force is responsible for the cohesiveness of water?

A) osmosis
B) hydrogen bonding between water molecules
C) negative pressure created by evaporation
D) ionic bonding

Question 11

________ pulls water through a plant.

A) Transpiration
B) Photosynthesis
C) Pressure flow
D) Adhesion

Question 12

The pores that facilitate gas exchange in plant leaves are called

A) stomata.
B) guard cells.
C) vacuoles.
D) plasmodesmata.

Question 13

Aphids are small insects that insert their mouthparts into a plant to obtain phloem sap. Which would be the best way to determine if aphids must actively draw phloem sap into their digestive tract or if hydrostatic pressure in the phloem tube could force the sap into them?

A) Isolate a phloem tube from a plant, allow an aphid to insert its mouthparts, and see if the aphid can still take up sap from it.
B) Measure relative rates of sugar manufacture in leaves with and without aphids.
C) Insert mouthparts removed from an aphid, without including the digestive tract, into phloem sap and see if sap keeps flowing through them.

Question 14

The loss of water from the leaves of plants is

A) adhesion.
B) cohesion.
C) transpiration.
D) osmosis.

Question 15

Which option best describes the mechanism that causes a stoma to open?

A) K+ enters the guard cells and water follows passively, making the cells turgid.
B) K+ activates water pumps in the guard cell membrane that make them turgid.
C) K+ leaves the guard cells and water follows passively, making the cells flaccid.
D) Loss of K+ from guard cells creates positive pressure and expands the guard cells.

Question 16

What is the physical barrier in the root that regulates the flow of water to xylem via cell walls?

A) phloem
B) epidermis
C) Casparian strip
D) cortex

Question 17

For water transport in vascular plants, the cohesive property of water is most important in the

A) epidermis.
B) xylem.
C) internal air spaces.
D) stomata.

Question 18

In an attempt to determine the source of a growing plant's mass, van Helmont planted a willow seedling in a pot of soil. After 5 years, the willow weighed 76.8 kg, and the soil had lost 0.06 kg of weight. Only water had been added to the pot. Which conclusion should van Helmont have drawn?

A) Plants get their mass from water.
B) Plants get their mass from water and air.
C) Plants get their mass from water and atmospheric CO2.
D) Plants get all or almost all of their mass from a source other than soil.

Question 19

Which condition would be most likely to cause stomata to open?

A) high levels of carbon dioxide in a leaf
B) hot, dry weather and strong winds
C) sunrise on a clear morning
D) a cool night setting in

Question 20

The sugar "sink" in roots is the result of

A) active transport of mineral ions into xylem cells.
B) absorption of water from the soil through epidermal cells.
C) active transport of sugars from phloem to root cells.
D) the pull of gravity on sugar molecules.

Question 21

On a trip to the Southwest United States, you and a friend collect some seeds from a piñon, a type of pine tree. Your friend also gathers a small bagful of soil from under the piñon tree. Back home, both of you plant your seeds in commercial sterilized potting soil, but your friend adds a spoonful of the collected dirt to each of her pots. Her seedlings do better than yours. What is the likeliest explanation for your differences?

A) Pine seedlings are better adapted to the sandy soil of the Southwest than to commercial potting mix.
B) The soil from the Southwest probably contained macronutrients missing from the potting mix.
C) The soil from the Southwest probably contained nitrogen-fixing bacteria that colonized the seedlings' root nodules.
D) The soil from the Southwest probably contained fungi able to establish a mycorrhizal association with the seedlings' roots.

Question 22

Which essential nutrient is most likely to leach from the soil?

A) Ca2+
B) Mg2+
C) K+
D) NO3−

Question 23

Commercial inorganic fertilizers have greatly increased agricultural productivity. What is an advantage of using inorganic rather than organic fertilizers?

A) It is easier for plants to absorb nutrients in an inorganic form.
B) Nutrients are released faster from inorganic fertilizers.
C) Inorganic nutrients bind more tightly to soil particles.
D) Inorganic fertilizers increase the water-holding capacity of the soil.

Question 24

What form of nitrogen can most plants absorb and use directly?

A) nitrite and nitrate
B) nitrate only
C) ammonium and nitrogen gas
D) nitrate and ammonium

Question 25

Why don't the countries that most need high-protein crops grow them?

A) High-protein crops usually require fertilizers, which may not be affordable to these countries.
B) High-protein crops require extensive irrigation, which may not be affordable to these countries.
C) High-protein crops are more difficult to process, making the foods they produce too expensive.
D) High-protein crops are typically low in most other vital nutrients.

Question 26

Nitrogen fixation consists of the

A) conversion of ammonia to nitrate.
B) production of ammonium from decomposing organic matter.
C) conversion of N2 to ammonia.
D) conversion of N2 to ammonia or nitrate.

Question 27

What are the macronutrients present in most commercial fertilizers?

A) C, H, and N
B) N, P, and K
C) C, N, and P
D) N, C, and K

Question 28

Micronutrients function in plants mainly as

A) joining elements in organic molecule carbon skeletons.
B) regulators of membrane transport.
C) cofactors in chemical reactions.
D) food reserves for pollen grains.

Question 29

The relationship between a plant and mycorrhizal fungi is best described as

A) parasitic.
B) competitive.
C) mutualistic.
D) commensal.

Question 30

If you examine the soil profile revealed by a fresh road cut, which feature will you probably find in the B horizon?

A) an abundance of worms and burrowing insects
B) an abundance of decomposing organic material
C) an abundance of fine clay but not much organic material
D) a predominance of slightly weathered rock and gravel

Question 31

Which of the following are important in breaking down organic material in fertile topsoil?

A) rock particles
B) humus and cations
C) bacteria and fungi
D) plant roots

Question 32

Compared to conventional agriculture, organic farming

A) uses fewer synthetic pesticides.
B) increases crop yields.
C) guarantees the safety and extra health benefits of food.
D) requires much less hands-on work.

Question 33

How do sugars move from one sieve-tube cell to the next?

A) by osmotic diffusion through the sieve plate
B) by flowing along with water through perforations in the sieve plate
C) by active transport across cell membranes at the sieve plate
D) by diffusion through a companion cell that spans the sieve plate

Question 34

What is a potential problem with the use of transgenic varieties of plants that contain Bt toxin?

A) Bt toxin may be harmful to humans.
B) Bt toxin may be harmful to some beneficial insects.
C) Transgenic crop varieties with Bt toxin are not very hardy and require a lot of care.
D) Transgenic crop varieties with Bt toxin require large amounts of chemical insecticides to grow.

Question 35

Which list shows the set of plant macronutrients that make up about 98% of a plant's dry weight?

A) carbon, oxygen, hydrogen, potassium, zinc, and copper
B) carbon, nitrogen, potassium, manganese, sulfur, and phosphorus
C) nitrogen, potassium, manganese, sulfur, copper, and phosphorus
D) carbon, oxygen, hydrogen, nitrogen, sulfur, and phosphorus

Question 36

"Smart" plants can reduce overuse of fertilizers by

A) using photosynthesis and fungal relationships to generate their own fertilizer.
B) informing the grower of a nutrient deficiency before damage occurs.
C) slowing the process of minerals washing out of the soils.
D) storing fertilizers in their root systems until they are needed.

Question 37

What is the role of the fungus in a mycorrhizal association?

A) contribution to photosynthesis
B) absorption of water, phosphate, and other minerals
C) secretion of growth factors
D) release of water

Question 38

Which nitrogen-phosphorous-potassium ratio in a fertilizer would most likely solve the problem of yellowed leaves and stunted growth?

A) 20:0:0
B) 0:20:0
C) 0:0:20
D) 0:20:20

Question 39

Which essential macronutrient for plants is obtained directly from the air?

A) nitrogen
B) magnesium
C) hydrogen
D) carbon

Question 40

Why was drip irrigation developed?

A) It uses less water than traditional irrigation methods.
B) It increases soil erosion.
C) It increases soil salinity.
D) It increases evaporation and drainage.

Question 41

Carnivorous plants are more likely to be found in acid bogs because

A) organic matter decays so slowly there.
B) acid soil inhibits growth of plant roots.
C) acid rain damages leaves and stems.
D) mycorrhizal growth is inhibited.

Question 42

After reading the paragraph below, answer the questions that follow.
Plants are sometimes used for phytoremediation in areas where the soil has been contaminated with heavy metals. Suppose the Acme Remediation Company is proposing to remediate a contaminated area that you wish to restore. Acme presents you with the following data as evidence of their company's ability to remediate soil.

To decide if you want Acme to remediate the contaminated area, which question should you ask Acme about conclusions to be drawn from these data?

A) What unit of measurement was used to determine how much metal was in the soil?
B) What levels of heavy metals did it begin with to demonstrate the effectiveness of remediation?
C) Since even the control plots lost metals, do I really need to remediate?
D) Since lead (Pb) is not a micronutrient for plants, how do the plants remove it?

Question 43

Carnivory in plants is primarily an adaptation for

A) growing in soil poor in organic material.
B) growing in soil poor in usable nitrogen.
C) obtaining supplemental carbon for photosynthesis.
D) discouraging herbivorous insects.

Question 44

An example of an organism that parasitizes a host plant is

A) a mycorrhizal fungus.
B) nitrogen-fixing bacteria in root nodules.
C) a Venus flytrap.
D) mistletoe.

Question 45

The term carnivorous as applied to carnivorous plants is not considered accurate by some biologists because

A) carnivorous plants use insects for nitrogen and minerals; an organism would have to use insects as a source of energy and matter as well to be a carnivore.
B) carnivorous plants only use insects as pollinators and do not gain any nutrients from them.
C) carnivorous plants do not digest whole insects; an organism would have to digest whole insects to be considered a carnivore.
D) carnivorous plants do not move around; an organism must be able to move to be considered a carnivore.

Question 46

Use the figure below to answer the questions that follow.

Under what circumstances would guard cells look like those in the right panel?

A) a cool rainy day
B) a hot humid day
C) at elevated levels of CO2
D) a hot dry day

Question 47

A small seed may grow into a very large tree. As the tree grows, it adds a great deal of mass. Where does most of this mass come from?

A) air
B) soil
C) water
D) sunlight

Question 48

What can you conclude from this figure?

A) The clay particle has a negative charge at its surface.
B) The clay particle has a positive charge at its surface.
C) The clay particle has a neutral charge at its surface.
D) The plant does not need K+.

Question 49

According to this figure, what can directly use atmospheric N2?

A) plant roots
B) nitrogen-fixing bacteria
C) ammonifying bacteria
D) nitrifying bacteria

Question 50

A peanut farmer decides that she can make more money growing cotton and so plants her fields with cotton. The terrific yield of her fields is so encouraging that she continues to plant cotton for several more years, but each year her cotton yield decreases. What advice could you give her to increase her yield?

A) Use a little less fertilizer each year since the soil is becoming overfertilized.
B) Plant peanuts in alternate years since this crop rotation will provide extra nitrogen to the soil.
C) Leave the fields unplanted in alternate years so the soil can recover.
D) Plant a different crop every year since different crops deplete different soil nutrients.

Question 51

Much research is being done to increase the nitrogen-fixing ability of plants with root nodules. Why is this an important goal for agricultural researchers?

A) Decreasing the size of nodules will allow plants to fix more nitrogen into their own molecules.
B) Nitrogen is an essential component of the amino acids used to form protein.
C) Increasing the nitrogen-fixing ability of plants will allow them to make better use of nitrogen fertilizers.
D) Removing the bacteria from the root nodules will allow more fixed nitrogen to be available to the plants.

Question 52

After reading the paragraph below, answer the questions that follow.
Plants are sometimes used for phytoremediation in areas where the soil has been contaminated with heavy metals. Suppose the Acme Remediation Company is proposing to remediate a contaminated area that you wish to restore. Acme presents you with the following data as evidence of their company's ability to remediate soil.

What likely caused the loss of metals in the control soil?

A) being washed away by water draining through the soil
B) evaporation of the metal molecules into the air
C) absorption of the metal molecules by clay particles
D) buildup of humus

Question 53

After reading the paragraph below, answer the questions that follow.
Plants are sometimes used for phytoremediation in areas where the soil has been contaminated with heavy metals. Suppose the Acme Remediation Company is proposing to remediate a contaminated area that you wish to restore. Acme presents you with the following data as evidence of their company's ability to remediate soil.

According to the data, this remediation plan is most effective with which element?

A) cadmium (Cd)
B) copper (Cu)
C) lead (Pb)
D) zinc (Zn)

Question 54

Which of these studies is a meta-analysis?

A) a study that examined a link between nitrogen in the soil and yellowing of leaves
B) a study that summarized research reports from many laboratories around the world indicating a relationship between a diet high in plants and colon cancer
C) a study that reported on seed germination rates at many different temperatures
D) a study that related transpiration rates in a number of different plants to weather conditions over many areas in North America

Question 55

After reading the paragraph below, answer the questions that follow.
Plants are sometimes used for phytoremediation in areas where the soil has been contaminated with heavy metals. Suppose the Acme Remediation Company is proposing to remediate a contaminated area that you wish to restore. Acme presents you with the following data as evidence of their company's ability to remediate soil.

Which would provide the best evidence that Acme's phytoremediation really works?

A) data on heavy metal content of plants grown in normal soil versus soil contaminated with heavy metals
B) testimonials from former Acme customers
C) a list of plant species that tolerate heavy metals
D) a list of publications of the scientists that work at Acme

Question 56

Use the figure below to answer the questions that follow.

What is true of the guard cells shown in the right-hand panel of this figure?

A) Their turgor pressure is increasing.
B) Potassium (K) is entering these cells.
C) These cells are hypertonic to their immediate surroundings.
D) These cells are hypotonic to their immediate surroundings.

Question 57

Legumes are frequently grown in rotation with primary field crops. What is the benefit of this practice?

A) A greater amount of the primary crop can be harvested each year.
B) The legumes' symbiotic nitrogen-fixing bacteria add nitrogen to the soil.
C) Soil erosion is reduced by frequent plowing.
D) Legumes decrease the amount of organic material in the soil.

Question 58

A gardener planted large, healthy flower bulbs in her garden. When spring arrived, green shoots emerged from the bulbs, and some of them, but not all, produced flowers. She decided to dig up a few bulbs that flowered and a few that didn't to see if she could see what the difference was. She was stunned to find that none of the bulbs looked healthy; they all appeared much smaller. What had happened?

A) The bulbs were a sugar source; sugars from them traveled up the phloem to the aboveground sugar sink.
B) The bulbs gave off water as they produced shoots; their smaller size was due to dehydration.
C) All of the molecules in the bulb were transferred to the aboveground shoots.
D) The bulbs were a sugar sink, so water flowed into them and out the roots, washing material from the bulb into the soil.

Question 59

What is most likely to be an epiphyte?

A) a plant growing on the branches of another plant
B) a plant that captures insects
C) a plant with a very deep root system
D) a plant that parasitizes another plant

Question 60

Legumes, such as beans or peas

A) form mutualistic associations with nitrogen-fixing bacteria.
B) form mycorrhizal associations to increase nitrogen fixation in the soil.
C) form parasitic relationships with other photosynthetic plants.
D) fix N2 from the atmosphere in their leaves.

Question 61

The corporation Bayer produces an herbicide called Liberty and the LibertyLink soybean, a genetically modified soybean that is resistant to this herbicide. The genetic modification allows soybeans to produce a protein that is able to destroy the Liberty herbicide. Thus, when a farmer sprays the Liberty herbicide on a weed-infested field of LibertyLink soybeans, only susceptible weeds, and not the farmer's soybean crop, die. One weed that farmers would like to get rid of is dodder (Cuscuta pentagona) a plant that uses chemical cues to find other plants such as soybeans. When a soybean plant is found, dodder wraps its leafless stems around the soybean and uses modified roots to tap into the soybean's vascular system. Because of the physical connection between a soybean plant and dodder, scientists hypothesized that dodder could obtain substances from the soybean plant other than nutrients, sugar, and water. They predicted that dodder would be able to gain the protein that destroys the Liberty herbicide. They tested this hypothesis by growing dodder on LibertyLinksoybeans and then applying the Liberty herbicide to see if the dodder would die. Their results are displayed in the table.
$\begin{array}{|c|}\hline \text { Concentration of Herbicide }(\mathrm{g} / \mathrm{L})\\\begin{array}{l|l|l|l|l}\hline \text { Treatment } & 0 & 0.36 & 0.72 & 3.6 \\\hline \text { Dodder on LibertyLink } & & & & \\\text { soybean } & \text { Survived } & \text { Survived } & \text { Survived } & \text { Died } \\\hline \begin{array}{l}\text { Dodder on normal } \\\text { soybean }\end{array} & \text { Survived } & \text { Died } & \text { Died } & \text { Died } \\\hline\end{array}\end{array}$ Source: Adapted from Jiang, L., Qu, F., Li, Z., & Doohan, D. (2013). Inter?species protein trafficking endows dodder (Cuscuta pentagona) with a host?specific herbicide?tolerant trait. New Phytologist, 198(4), 1017-1022.

-An alternative hypothesis to the translocation of the protein from the soybean to dodder is that the herbicide is translocated from the dodder to the soybean, and then the herbicide is destroyed in the soybean. What experimental results would rule out this alternative hypothesis?

A) After separating dodder from a LibertyLinksoybean, dodder survived 0.36 g/L of the herbicide.
B) After separating dodder from a LibertyLinksoybean, dodder survived 3.6 g/L of the herbicide.
C) Dodder that grew on normal soybean survived 0.36 g/L of the herbicide after being transferred to LibertyLink soybean.
D) Dodder that grew on LibertyLink soybean died from 0.36 g/L of the herbicide after being transferred to normal soybean.

Question 62

The corporation Bayer produces an herbicide called Liberty and the LibertyLink soybean, a genetically modified soybean that is resistant to this herbicide. The genetic modification allows soybeans to produce a protein that is able to destroy the Liberty herbicide. Thus, when a farmer sprays the Liberty herbicide on a weed-infested field of LibertyLink soybeans, only susceptible weeds, and not the farmer's soybean crop, die. One weed that farmers would like to get rid of is dodder (Cuscuta pentagona) a plant that uses chemical cues to find other plants such as soybeans. When a soybean plant is found, dodder wraps its leafless stems around the soybean and uses modified roots to tap into the soybean's vascular system. Because of the physical connection between a soybean plant and dodder, scientists hypothesized that dodder could obtain substances from the soybean plant other than nutrients, sugar, and water. They predicted that dodder would be able to gain the protein that destroys the Liberty herbicide. They tested this hypothesis by growing dodder on LibertyLinksoybeans and then applying the Liberty herbicide to see if the dodder would die. Their results are displayed in the table.
$\begin{array}{|c|}\hline \text { Concentration of Herbicide }(\mathrm{g} / \mathrm{L})\\\begin{array}{l|l|l|l|l}\hline \text { Treatment } & 0 & 0.36 & 0.72 & 3.6 \\\hline \text { Dodder on LibertyLink } & & & & \\\text { soybean } & \text { Survived } & \text { Survived } & \text { Survived } & \text { Died } \\\hline \begin{array}{l}\text { Dodder on normal } \\\text { soybean }\end{array} & \text { Survived } & \text { Died } & \text { Died } & \text { Died } \\\hline\end{array}\end{array}$ Source: Adapted from Jiang, L., Qu, F., Li, Z., & Doohan, D. (2013). Inter?species protein trafficking endows dodder (Cuscuta pentagona) with a host?specific herbicide?tolerant trait. New Phytologist, 198(4), 1017-1022.

-Dodder gains nutrients by being a(n)

A) epiphyte.
B) carnivore.
C) parasite.
D) mycorrhiza.

Question 63

The corporation Bayer produces an herbicide called Liberty and the LibertyLink soybean, a genetically modified soybean that is resistant to this herbicide. The genetic modification allows soybeans to produce a protein that is able to destroy the Liberty herbicide. Thus, when a farmer sprays the Liberty herbicide on a weed-infested field of LibertyLink soybeans, only susceptible weeds, and not the farmer's soybean crop, die. One weed that farmers would like to get rid of is dodder (Cuscuta pentagona) a plant that uses chemical cues to find other plants such as soybeans. When a soybean plant is found, dodder wraps its leafless stems around the soybean and uses modified roots to tap into the soybean's vascular system. Because of the physical connection between a soybean plant and dodder, scientists hypothesized that dodder could obtain substances from the soybean plant other than nutrients, sugar, and water. They predicted that dodder would be able to gain the protein that destroys the Liberty herbicide. They tested this hypothesis by growing dodder on LibertyLinksoybeans and then applying the Liberty herbicide to see if the dodder would die. Their results are displayed in the table.
$\begin{array}{|c|}\hline \text { Concentration of Herbicide }(\mathrm{g} / \mathrm{L})\\\begin{array}{l|l|l|l|l}\hline \text { Treatment } & 0 & 0.36 & 0.72 & 3.6 \\\hline \text { Dodder on LibertyLink } & & & & \\\text { soybean } & \text { Survived } & \text { Survived } & \text { Survived } & \text { Died } \\\hline \begin{array}{l}\text { Dodder on normal } \\\text { soybean }\end{array} & \text { Survived } & \text { Died } & \text { Died } & \text { Died } \\\hline\end{array}\end{array}$ Source: Adapted from Jiang, L., Qu, F., Li, Z., & Doohan, D. (2013). Inter?species protein trafficking endows dodder (Cuscuta pentagona) with a host?specific herbicide?tolerant trait. New Phytologist, 198(4), 1017-1022.

-Can the scientists conclude that the protein that destroys the herbicide is transferred to dodder from the soybean plant?

A) Yes, because the dodder on the LibertyLink soybean survived when lower concentrations of the herbicide were applied, while the dodder on normal soybean did not.
B) Yes, because the dodder on the normal soybean survived when lower concentrations of the herbicide were applied, while the dodder on LibertyLink soybean did not.
C) No, because all dodder dies at high concentrations of the herbicide.
D) No, because all dodder survives when no herbicide is applied.

Question 64

The corporation Bayer produces an herbicide called Liberty and the LibertyLink soybean, a genetically modified soybean that is resistant to this herbicide. The genetic modification allows soybeans to produce a protein that is able to destroy the Liberty herbicide. Thus, when a farmer sprays the Liberty herbicide on a weed-infested field of LibertyLink soybeans, only susceptible weeds, and not the farmer's soybean crop, die. One weed that farmers would like to get rid of is dodder (Cuscuta pentagona) a plant that uses chemical cues to find other plants such as soybeans. When a soybean plant is found, dodder wraps its leafless stems around the soybean and uses modified roots to tap into the soybean's vascular system. Because of the physical connection between a soybean plant and dodder, scientists hypothesized that dodder could obtain substances from the soybean plant other than nutrients, sugar, and water. They predicted that dodder would be able to gain the protein that destroys the Liberty herbicide. They tested this hypothesis by growing dodder on LibertyLinksoybeans and then applying the Liberty herbicide to see if the dodder would die. Their results are displayed in the table.
$\begin{array}{|c|}\hline \text { Concentration of Herbicide }(\mathrm{g} / \mathrm{L})\\\begin{array}{l|l|l|l|l}\hline \text { Treatment } & 0 & 0.36 & 0.72 & 3.6 \\\hline \text { Dodder on LibertyLink } & & & & \\\text { soybean } & \text { Survived } & \text { Survived } & \text { Survived } & \text { Died } \\\hline \begin{array}{l}\text { Dodder on normal } \\\text { soybean }\end{array} & \text { Survived } & \text { Died } & \text { Died } & \text { Died } \\\hline\end{array}\end{array}$ Source: Adapted from Jiang, L., Qu, F., Li, Z., & Doohan, D. (2013). Inter?species protein trafficking endows dodder (Cuscuta pentagona) with a host?specific herbicide?tolerant trait. New Phytologist, 198(4), 1017-1022.

-The modified roots of dodder grow into the stem of the host plant and into the host's xylem and phloem. Considering that water transport works the same in dodder as it does in other plants, trace the path of a single water molecule. Which list correctly orders the water molecule's path?

A) water molecule is pulled out of the soybean plant, water molecule is pulled out of the modified root and into dodder xylem, water molecule is pulled out of the dodder xylem, water molecule evaporates and diffuses out of dodder stomata
B) water molecule is pulled out of the modified root and into dodder xylem, water molecule evaporates and diffuses out of dodder stomata, water molecule is pulled out of the soybean plant, water molecule is pulled out of the dodder xylem
C) water molecule evaporates and diffuses out of dodder stomata, water molecule is pulled out of the xylem, water molecule is pulled out of the modified root and into xylem, water molecule is pulled out of the soybean plant
D) water molecule is pulled out of the dodder xylem, water molecule is pulled out of the modified root and into dodder xylem, water molecule evaporates and diffuses out of dodder stomata, water molecule is pulled out of the soybean plant

Question 65

After reading the paragraph below, answer the questions that follow.
Plants are sometimes used for phytoremediation in areas where the soil has been contaminated with heavy metals. Suppose the Acme Remediation Company is proposing to remediate a contaminated area that you wish to restore. Acme presents you with the following data as evidence of their company's ability to remediate soil.

The data provide evidence for which of the following?

A) The copper removal percentage was approximately doubled by the presence of the plants used to remediate the soil.
B) Before restoration efforts, there was twice as much lead in the soil as cadmium.
C) Phytoremediation is especially effective at removing zinc from the soil.
D) The most toxic product in the soil is lead.

Question 66

After reading the paragraphs below, answer the questions that follow.
Over the next several decades, world population growth will necessitate as much as a 60% increase in food production, primarily in developing countries. These countries are often the most seriously affected by drought and salinity. Even if irrigation water is available, flooding fields with irrigation water leads to the gradual accumulation of sodium ions and other salts in the soil.
To respond to this growing problem, scientists at the University of Connecticut have genetically engineered a plant that can survive in salty soil and withstand extended drought conditions. The new transgenic plant contains a gene for an ion pump. Salt ions are transported from the soil and stored in vacuoles in the cytoplasm. The enhanced uptake of ions into their vacuoles in turn improves water retention in the transgenic plants and their resistance to drought. The concentration of solutes inside and outside plant cells affects the direction of water movement through osmosis.
The researchers found that the salt concentration in the cells of the new transgenic plants was significantly higher than in wild plants used as a control. In addition, the transgenic plants survived longer when deprived of water.
Planting these transgenic crops periodically would be beneficial to the environment because

A) the plants would help clean accumulated salts deposited in the soil by irrigation.
B) the transgenic plants would fix nitrogen and improve soil fertility.
C) the plants would remove carbon dioxide and decrease global warming.
D) the plants would resist diseases and decrease herbicide use.

Question 67

The corporation Bayer produces an herbicide called Liberty and the LibertyLink soybean, a genetically modified soybean that is resistant to this herbicide. The genetic modification allows soybeans to produce a protein that is able to destroy the Liberty herbicide. Thus, when a farmer sprays the Liberty herbicide on a weed-infested field of LibertyLink soybeans, only susceptible weeds, and not the farmer's soybean crop, die. One weed that farmers would like to get rid of is dodder (Cuscuta pentagona) a plant that uses chemical cues to find other plants such as soybeans. When a soybean plant is found, dodder wraps its leafless stems around the soybean and uses modified roots to tap into the soybean's vascular system. Because of the physical connection between a soybean plant and dodder, scientists hypothesized that dodder could obtain substances from the soybean plant other than nutrients, sugar, and water. They predicted that dodder would be able to gain the protein that destroys the Liberty herbicide. They tested this hypothesis by growing dodder on LibertyLinksoybeans and then applying the Liberty herbicide to see if the dodder would die. Their results are displayed in the table.
$\begin{array}{|c|}\hline \text { Concentration of Herbicide }(\mathrm{g} / \mathrm{L})\\\begin{array}{l|l|l|l|l}\hline \text { Treatment } & 0 & 0.36 & 0.72 & 3.6 \\\hline \text { Dodder on LibertyLink } & & & & \\\text { soybean } & \text { Survived } & \text { Survived } & \text { Survived } & \text { Died } \\\hline \begin{array}{l}\text { Dodder on normal } \\\text { soybean }\end{array} & \text { Survived } & \text { Died } & \text { Died } & \text { Died } \\\hline\end{array}\end{array}$ Source: Adapted from Jiang, L., Qu, F., Li, Z., & Doohan, D. (2013). Inter?species protein trafficking endows dodder (Cuscuta pentagona) with a host?specific herbicide?tolerant trait. New Phytologist, 198(4), 1017-1022.

-With respect to translocation of sugars, a rapidly growing dodder plant is a ________ and the soybean plant is a ________.

A) source; sink
B) source; source
C) sink; source
D) sink; sink

Question 68

After reading the paragraph below, answer the questions that follow.
Plants are sometimes used for phytoremediation in areas where the soil has been contaminated with heavy metals. Suppose the Acme Remediation Company is proposing to remediate a contaminated area that you wish to restore. Acme presents you with the following data as evidence of their company's ability to remediate soil.

The CEO of Acme Remediation Company is always trying to improve the company's effectiveness by keeping up with current research. Which research topic should have the highest priority for that research?

A) comparison of plant species' tolerance of clay versus sandy soils
B) comparison of plant species' ability to live in dry versus moist soils
C) comparison of plant species' tolerance of heavy metals in soils
D) comparison of plant species' bioaccumulation of metal ions

Question 69

After reading the paragraphs below, answer the questions that follow.
Over the next several decades, world population growth will necessitate as much as a 60% increase in food production, primarily in developing countries. These countries are often the most seriously affected by drought and salinity. Even if irrigation water is available, flooding fields with irrigation water leads to the gradual accumulation of sodium ions and other salts in the soil.
To respond to this growing problem, scientists at the University of Connecticut have genetically engineered a plant that can survive in salty soil and withstand extended drought conditions. The new transgenic plant contains a gene for an ion pump. Salt ions are transported from the soil and stored in vacuoles in the cytoplasm. The enhanced uptake of ions into their vacuoles in turn improves water retention in the transgenic plants and their resistance to drought. The concentration of solutes inside and outside plant cells affects the direction of water movement through osmosis.
The researchers found that the salt concentration in the cells of the new transgenic plants was significantly higher than in wild plants used as a control. In addition, the transgenic plants survived longer when deprived of water.
The experimental plants were more drought resistant because

A) their vacuoles pumped water directly into the cytoplasm.
B) salt stored in their vacuoles enabled the cytoplasm to retain water better.
C) salt stored in their vacuoles was equal in amount to the salt in the soil.
D) water was stored in their vacuoles until the next rainfall.