Question 1

Which of the following best describes the mutualistic relationship between plants and soil microbes in the rhizosphere?

Accepted Answer

Plants provide dead organic matter and root secretions to microbes, while microbes enhance nutrient availability and protect roots.

Question 2

Which process in the nitrogen cycle is directly responsible for converting atmospheric $$N_2$$ into a form usable by plants?

Accepted Answer

Nitrogen fixation

Question 3

A farmer wants to increase the nitrogen content of her soil without using synthetic fertilizers. Which crop should she plant to maximize natural nitrogen fixation, and why?

Accepted Answer

Soybeans, because they form nodules with nitrogen-fixing Rhizobium bacteria.

Question 4

Which of the following is NOT a way that rhizobacteria and endophytes enhance plant growth?

Accepted Answer

Directly providing water to the plant through their own vascular tissue

Question 5

In the mutualistic association known as mycorrhizae, what is the primary benefit that the plant receives from the fungus?

Accepted Answer

Increased surface area for water and mineral absorption

Question 6

Which of the following statements about ectomycorrhizae is correct?

Accepted Answer

The fungal mycelium forms a dense sheath over the root surface and hyphae form a network in the apoplast.

Question 7

Which of the following best explains why garlic mustard is considered an invasive species in North American forests?

Accepted Answer

It slows the growth of other plants by preventing the growth of mycorrhizal fungi.

Question 8

Which of the following is a correct description of arbuscular mycorrhizae?

Accepted Answer

Fungal hyphae penetrate the cell wall but not the plasma membrane, forming arbuscules within root cells.

Question 9

A plant is observed growing on the branch of a tree, obtaining water and minerals from rain but not harming the host. This plant is best classified as a(n):

Accepted Answer

Epiphyte

Question 10

Which of the following is true about carnivorous plants such as pitcher plants and Venus flytraps?

Accepted Answer

They are photosynthetic but obtain nitrogen by digesting prey.

Question 11

Which of the following equations correctly represents the process of nitrogen fixation by Rhizobium bacteria?

Accepted Answer

$$N_2 + 8H^+ + 8e$$^- \rightarrow 2NH_3 + $$H_2$$

Question 12

A botanist discovers a plant that lacks chlorophyll and is found attached to the roots of another plant’s mycorrhizal fungi. What is the most likely nutritional strategy of this plant?

Accepted Answer

Parasitic on mycorrhizae

Question 13

Which of the following is a real-world example of a mutualistic relationship between an animal and a fungus?

Accepted Answer

Leaf-cutter ants cultivating fungal gardens in their nests

Question 14

Which of the following best explains why legumes are often used in crop rotation to improve soil fertility?

Accepted Answer

They form symbiotic relationships with nitrogen-fixing bacteria, increasing soil nitrogen.

Question 15

Which of the following is a correct sequence of events in the nitrogen cycle as it relates to plant nutrition?

Accepted Answer

Nitrogen fixation $$\rightarrow$$ Ammonification $$\rightarrow$$ Nitrification $$\rightarrow$$ Assimilation

Question 16

Which of the following adaptations would most likely be found in a plant growing in a nitrogen-poor, acidic bog?

Accepted Answer

Development of carnivorous structures to trap insects

Question 17

Which of the following is a plausible consequence if a plant’s mycorrhizal fungi are destroyed by an invasive species?

Accepted Answer

The plant will have reduced water and mineral uptake, leading to stunted growth.

Question 18

Which of the following best describes the nutritional strategy of mistletoe?

Accepted Answer

It is a photosynthetic parasite that absorbs water and minerals from its host.

Question 19

Which of the following is a key difference between ectomycorrhizae and arbuscular mycorrhizae?

Accepted Answer

Arbuscular mycorrhizae form arbuscules inside root cells, while ectomycorrhizae form a sheath around the root.

Plant Nutrition and Symbiotic Relationships

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