Question 1

A researcher is looking at different petri dishes that contain the yeast C. albicans. In the first dish she evaluates, she notices that the yeast do not form hyphae. Is this a mutant strain of yeast?
A)Yes, because the lack of hyphae denotes pathogenic yeast.
B)Yes, because yeast typically form hyphae.
C)No, because yeast do not normally form hyphae.
D)No, because yeast always form rhizoids and not hyphae.

Accepted Answer

Yeast do not normally form hyphae, so the lack of hyphae in the first dish does not necessarily indicate a mutant strain of yeast.

Question 2

What is the specific role of cyanobacteria (or green algae) in lichens?
A)to help attach the lichens to surfaces
B)to synthesize defensive compounds
C)to provide fungi with carbohydrates produced by photosynthesis
D)to transport water throughout lichens
E)Cyanobacteria and green algae play no role in lichens, because lichens consist of fungi.

Accepted Answer

Cyanobacteria (or green algae) in lichens provide fungi with carbohydrates produced by photosynthesis, which the fungi cannot produce on their own. This is known as a mutualistic relationship, as the cyanobacteria (or green algae) benefit from protection and a stable environment provided by the fungi.

Question 3

What is the primary reason that fungi are important in the carbon cycle?
A)Fungi are able to reach incredibly large sizes, storing carbon while they are alive, and contributing carbon back to the atmosphere when they die and decompose.
B)Fungi are able to reach incredibly large sizes. Their high ratio of surface area to volume allows them to decompose large amounts of dead/decaying material, thereby returning carbon to the atmosphere.
C)Fungi are able to reach incredibly large sizes. They have a high ratio of surface area to volume and are able to fix more carbon through photosynthesis than other plants of comparable size.
D)Fungi are able to reach incredibly large sizes. Their high ratio of surface area to volume allows them to store more carbon (in the form of sugar)obtained through mycorrhizal associations than their symbiotic hosts.

Accepted Answer

Fungi play an important role in the carbon cycle by decomposing dead and decaying matter, returning carbon to the atmosphere. Fungi have a high surface area to volume ratio, which allows them to decompose large amounts of organic material quickly and efficiently. This process releases carbon dioxide back into the atmosphere as a byproduct of decomposition. Therefore, option B is the best choice.

Question 4

Many antibiotics work by inhibiting the synthesis of peptidoglycan, a component of the bacterial cell wall. What is a possible mechanism of action for anti-fungal drugs?
A)inhibiting the synthesis of peptidoglycan in fungi
B)inhibiting the synthesis of cellulose in fungi
C)inhibiting the synthesis of chitin in fungi
D)inhibiting the synthesis of lignin in fungi

Accepted Answer

Many anti-fungal drugs work by inhibiting the synthesis of chitin, a component of the fungal cell wall. This weakens the cell wall and makes it susceptible to damage, ultimately leading to the death of the fungal cell.

Question 5

In some of the earliest plant fossils, there is evidence of mycorrhizal associations. Fungi may have been instrumental in plant colonization of land by:
A)colonizing areas as lichens and facilitating dispersal by terrestrial plants.
B)increasing nutrient uptake by early plant species.
C)increasing levels of organic matter in the soil.
D)releasing antibiotics to kill bacteria in the soil where plants would colonize.

Accepted Answer

Mycorrhizal associations between fungi and early plants allowed for increased nutrient uptake, particularly phosphorus, which was limited in early, nutrient-poor soils. This provided an advantage for plant colonization of land.

Question 6

How do the two species that make up a lichen benefit from their symbiotic association?
A)The fungi receive carbohydrates from the algae, while the algae receive nitrogen from the fungi.
B)Both partners are able to grow on substrates on which each would not be able to grow on their own.
C)The algae receive carbon as a result of the fungi's ability to degrade lignin and cellulose, while the fungi receive nitrogen from the algae.
D)The fungi receive carbohydrates and, in some cases nitrogen, from the algae, while the algae gain a "home" that anchors them on the substrate.

Accepted Answer

The answer of How do the two species that make...

Question 7

How do fungi digest their food sources?
A)by engulfing food particles and digesting them in vacuoles
B)by extending hyphae into a food source (e.g., an animal carcass)
C)by secreting enzymes externally, directly into their surrounding environment
D)by funneling food particles through septa, which break down larger molecules

Accepted Answer

The answer of How do fungi digest their food sources?
A)by...

Question 8

Imagine that you are on a nature walk. Your guide points out a lichen growing on a tree trunk and comments that lichens are actually a type of fungi. You know that this description is not correct. Why?
A)Lichens are actually vascular plants that produce hyphae instead of roots.
B)Lichens are actually composed of both fungi and green algae (or cyanobacteria).
C)Lichens are actually composed of both fungi and bryophytes.
D)Lichens are actually bryophytes that produce hyphae instead of roots.

Accepted Answer

Lichens are not just fungi, but a symbiotic relationship between a fungus and either green algae or cyanobacteria. They are not vascular plants or bryophytes, although they do have hyphae-like structures.

Question 9

How does the size of fungal hyphae contribute to their ability to decompose detritus?
A)Fungal hyphae have a low ratio of surface area to volume, so they are able to absorb more nutrients.
B)Fungal hyphae have high ratio of surface area to volume, so they are able to absorb more nutrients.
C)Fungal hyphae have a low ratio of surface area to volume, so they are able to secrete more digestive enzymes into the surrounding environment to break down detritus.
D)Fungal hyphae have a high ratio of surface area to volume, so they are able to secrete enzymes into a greater area of soil to break down detritus.

Accepted Answer

Fungal hyphae have a high surface area to volume ratio, which allows them to efficiently absorb nutrients and secrete enzymes over a large area, aiding in the decomposition of detritus.

Question 10

Consider the figure below. The bars show changes in primary productivity with and without endomychorrhizal associations for a group of plants that diverged early in the history of terrestrial plants. Which of the following statements supports the data shown in the figure? A)Endomycorrhizal associations do not increase primary productivity in these plants. B)Endomycorrhizal associations increase primary productivity in these plants. C)Endomycorrhizal associations only help these plants at high CO₂ concentrations. D)Endomycorrhizal associations only help these plants at low CO₂concentrations.

Accepted Answer

The bars show that the primary productivity is increased with the presence of endomycorrhizal associations, indicating that endomycorrhizal associations increase primary productivity in these plants.

Question 11

A gardener applies a specific fungicide to her plot that kills all mycorrhizal fungi. Which of the graphs below depicts changes in the amount of phosphorus in the soil after application of the fungicide? 
A)graph A
B)graph B
C)graph C

Accepted Answer

The answer of A gardener applies a specific fungicide to...

Question 12

Which plant-fungal symbionts exchange nutrients with their host plant MOST efficiently?
A)ectomycorrhizal symbionts
B)endomycorrhizal symbionts
C)endophytic symbionts

Accepted Answer

Endomycorrhizal symbionts have the highest efficiency in exchanging nutrients with their host plant. This is because the fungal hyphae of endomycorrhizal symbionts penetrate the root cells of the host plant, creating an intimate connection between the plant and the fungus. This allows for a more direct exchange of nutrients, such as phosphorus and nitrogen, between the two organisms. Ectomycorrhizal symbionts form a sheath around the root, increasing the surface area for nutrient exchange but not penetrating the root. Endophytic symbionts live within plant tissues but do not necessarily exchange nutrients with the plant.

Question 13

Yeasts are unicellular fungi that do not produce hyphae. However, they are descended from a common ancestor that did produce hyphae. Which of the following statements explains why yeasts do not produce hyphae?
A)Hyphae require many cells, so a unicellular organism is unable to produce hyphae.
B)Yeasts grow in nutrient-rich environments, so they do not require hyphal growth to reach regions high in nutrients.
C)Yeasts are descended from unicellular bacteria, and hyphal growth is not a characteristic of bacteria.
D)Yeasts are representative of the earliest fungal lineages before hyphal growth evolved in the group.

Accepted Answer

Yeasts typically inhabit nutrient-rich environments where the extensive surface area provided by hyphae is not necessary for nutrient absorption.

Question 14

Saprophytic (something that lives on dead and decaying material) fungi are essential to life on Earth because they: A)grow in mycorrhizal association with the roots of most plants, providing minerals to the plants. B)speed the recycling of nutrients. C)help to digest sap in phloem of dead and dying trees. D)recycle organic compounds into inorganic compounds. E)respire like plants taking in CO₂ and decrease greenhouse gasses.

Accepted Answer

Saprophytic fungi play a crucial role in the process of nutrient cycling by breaking down dead and decaying material and returning important nutrients to the soil. This allows other organisms, such as plants, to utilize these nutrients and continue the cycle of life.

Question 15

The majority of an individual fungus lives "in" its food source. What characteristics of the fungal growth form make this a necessity?
A)Fungi have a high ratio of surface area to volume and are highly susceptible to dessication.
B)Fungi have a low ratio of surface area to volume and are highly susceptible to dessication.
C)Fungi require the stimulus of "pushing" through the substrate to stimulate growth.
D)Fungi require more nutrients than other organisms, and large amounts of nutrients can only be acquired by living in a host.

Accepted Answer

Fungi have a high ratio of surface area to volume, which aids in absorption of nutrients but also makes them highly susceptible to drying out (dessication). Living within their food source helps maintain the necessary moisture for survival and nutrient absorption.

Question 16

Why might endophytes be able to help protect trees from pathogens that infect their leaves?
A)Because fungal endophytes produce hyphae, they have a greater chance of encountering pathogens within the leaf.
B)Because fungal endophytes can degrade cellulose and lignin, they are able break down the cell walls of many plant pathogens.
C)Because fungal endophytes disperse spores through the air, they are able to spread to leaves even at the tops of tall trees.
D)Because fungal endophytes have a shorter generation time than trees, they can more rapidly evolve new defenses.
E)Because fungal endophytes have cell walls containing chitin, they are able to present a larger diversity of receptor molecules on their surface that can detect pathogens.

Accepted Answer

Endophytes can evolve more rapidly than trees due to their shorter generation times, allowing them to develop new defenses against pathogens more quickly.

Question 17

Many people can get an infection called ringworm, which isn't a worm but a fungus. The characteristic growth pattern is a circle on the infected portion of the skin. The edges of the circle tend to appear redder, or more irritated, than the center. Where did the infection begin?
A)It began at the margins of the circle where it is most irritated, and the fungus grew around the margin of the circle.
B)It began at the center of the circle, and the fungus grew out from the initial point of infection.
C)Multiple fungal spores landed in the shape of the circle and led to infection.

Accepted Answer

Ringworm infections typically begin at a single point of infection and then spread outwards in a circular pattern. The center of the circle represents the initial point of infection, and the edges of the circle become more irritated as the fungus continues to grow outward.

Question 18

If all of the fungi on Earth ceased to exist, what would happen to the local carbon cycle? A)Because fungi are photosynthetic, less CO₂ would be removed from the atmosphere. B)Because fungi are decomposers, less CO₂ would be released back into the atmosphere. C)Because fungi are photosynthetic, more CO₂ would be removed from the atmosphere. D)Because fungi are decomposers, more CO₂ would be released back into the atmosphere.

Accepted Answer

Fungi play a crucial role in the carbon cycle as decomposers, breaking down dead organic material and releasing carbon dioxide (CO2) back into the atmosphere. Without fungi, this process would be significantly hindered, leading to less CO2 being released.

Question 19

How do fungi in the soil of rain forests encourage plant diversity?
A)By serving as pathogens for particular plant species, fungi favor the establishment of less-common plant species.
B)By serving as pollinators, fungi introduce plant diversity into new regions.
C)By forming mycorrizhae with plants, fungi introduce plant diversity into new regions.

Accepted Answer

Fungi in the soil can act as pathogens to certain plant species, which can prevent those species from becoming overly dominant, thus allowing less-common species to establish and maintain plant diversity.

Question 20

Recall that the phloem sap of vascular plants moves through the phloem as a result of turgor pressure. How are nutrients transported through fungi?
A)through hyphae, as a result of turgor pressure
B)through sieve tubes, as a result of turgor pressure
C)through vessel elements, as a result of turgor pressure
D)through hyphae, as a result of capillary action
E)through sieve tubes, as a result of capillary action

Accepted Answer

Nutrients in fungi are transported through hyphae, the thread-like structures that make up the body of the fungus. This process is driven by turgor pressure, similar to the mechanism in vascular plants but without the specialized structures like sieve tubes or vessel elements.

Quiz 34: Fungi: Structure, Function, and Diversity

A researcher is looking at different petri dishes that contain the yeast C. albicans. In the first dish she evaluates, she notices that the yeast do not form hyphae. Is this a mutant strain of yeast?

What is the specific role of cyanobacteria (or green algae) in lichens?

What is the primary reason that fungi are important in the carbon cycle?

Many antibiotics work by inhibiting the synthesis of peptidoglycan, a component of the bacterial cell wall. What is a possible mechanism of action for anti-fungal drugs?

In some of the earliest plant fossils, there is evidence of mycorrhizal associations. Fungi may have been instrumental in plant colonization of land by:

How do the two species that make up a lichen benefit from their symbiotic association?

How do fungi digest their food sources?

Imagine that you are on a nature walk. Your guide points out a lichen growing on a tree trunk and comments that lichens are actually a type of fungi. You know that this description is not correct. Why?

How does the size of fungal hyphae contribute to their ability to decompose detritus?

Consider the figure below. The bars show changes in primary productivity with and without endomychorrhizal associations for a group of plants that diverged early in the history of terrestrial plants. Which of the following statements supports the data shown in the figure?

A gardener applies a specific fungicide to her plot that kills all mycorrhizal fungi. Which of the graphs below depicts changes in the amount of phosphorus in the soil after application of the fungicide?

Which plant-fungal symbionts exchange nutrients with their host plant MOST efficiently?

Yeasts are unicellular fungi that do not produce hyphae. However, they are descended from a common ancestor that did produce hyphae. Which of the following statements explains why yeasts do not produce hyphae?

Saprophytic (something that lives on dead and decaying material) fungi are essential to life on Earth because they:

The majority of an individual fungus lives "in" its food source. What characteristics of the fungal growth form make this a necessity?

Why might endophytes be able to help protect trees from pathogens that infect their leaves?

Many people can get an infection called ringworm, which isn't a worm but a fungus. The characteristic growth pattern is a circle on the infected portion of the skin. The edges of the circle tend to appear redder, or more irritated, than the center. Where did the infection begin?

If all of the fungi on Earth ceased to exist, what would happen to the local carbon cycle?

How do fungi in the soil of rain forests encourage plant diversity?

Recall that the phloem sap of vascular plants moves through the phloem as a result of turgor pressure. How are nutrients transported through fungi?