Fungi and Forests
Mushrooms are the above-ground fruiting bodies of certain types of fungi. Fungi are diverse and adaptable, and they live in many different environments. Many fungi live in the soil, where their threadlike filaments fan out and tangle together into cords through the dirt, creating paths for interspecies interactions (interactions between different species). Many people think fungi are plants, but they are actually closer to animals. Fungi do not make their food from sunlight, as plants do. Like animals, fungi must find something to eat. Yet fungi obtain not only food for themselves but also make nutrients for other organisms. This occurs because fungi have digestion that is extracellular (taking place outside the cells). They excrete digestive acids outside their bodies to break down organic materials into nutrients. It is as if they had everted (inside out) stomachs, digesting food outside instead of inside their bodies. Nutrients are then absorbed into their cells, allowing the fungal body to grow-but also other species’ bodies. The reason there are plants growing on dry land rather than just in water is that over the course of Earth’s history, fungi have released digestive chemicals that break down rocks, making mineral nutrients available for plants. Fungi(together with bacteria) make the soil in which plants grow. Fungi also break down wood. Otherwise, dead trees would stack up in the forest forever. Fungi break them down into nutrients that can be recycled into new life. Fungi are thus world builders, shaping environments for themselves and others.
Some fungi have learned to live in intimate associations with plants, and given enough time to adjust to the interspecies relations of a place, most plants enter into associations with fungi. Endophytic and endomycorrhizal fungi live inside plants. Many do not have fruiting bodies. We are likely never to see these fungi unless we peer inside plants with microscopes, yet most plants are thick with them. Ectomycorrhizal fungi, on the other hand, wrap themselves around the outsides of roots as well as penetrate between their cells. Many of the favorite mushrooms of people around the world-porcini, chanterelles, truffles, and matsutake-are the fruiting bodies of ectomycorrhizal fungi associated with plants. They are so delicious, and so difficult for humans to manipulate, because they thrive together with host trees. They come into being only through interspecies relations.
The term “mycorrhiza” is assembled from Greek words for “fungus” and “root”; fungi and plant roots become intimately entangled in mycorrhizal relations. Neither the fungus nor the plant can flourish without the activity of the other. From the fungal perspective, the goal is to get a good meal. The fungus extends its body into the host’s roots to remove some of the plant’s carbohydrates through specialized structures, made in the encounter. The fungus depends on this food, yet it is not entirely selfish. Fungi stimulate plant growth in two ways: first by getting plants more water, and second by making the nutrients of extracellular digestion available to plants. Plants get calcium, nitrogen, potassium, phosphorus, and other minerals through mycorrhiza. Forests, according to researcher Lisa Curran, occur only because of ectomycorrhizal fungi. By leaning on fungal companions, trees grow strong and numerous, making forests.
Mutual benefits do not lead to perfect harmony. Sometimes the fungus parasitizes the root in one phase of the plant’s life cycle, exploiting the root for nutrients but giving nothing in return. Or if the plant has lots of nutrients, it may reject the fungus. A mycorrhizal fungus without a plant collaborator will die. But many ectomycorrhizas are not limited to one collaboration; the fungus forms a network across plants. In a forest, fungi connect not just trees of the same species, but often many species. If you cover a tree in the forest, depriving its leaves of light and thus food, its mycorrhizal associates may feed it from the carbohydrates of other trees in the network. Some commentators compare mycorrhizal networks to the Internet, writing of the “woodwide web,” as mycorhizas form an infrastructure of interspecies interconnection, carrying information across the forest. They also have some of the characteristics of a highway system. Soil microbes that would otherwise stay in the same place are able to travel in the channels and linkages of mycorrhizal interconnection. Some of these microbes are important for the removal of contaminants from soil. Mycorrhizal networks allow forests to respond to threats by, for example, mobilizing bacteria that degrade pollutants.
1
Mushrooms are the above-ground fruiting bodies of certain types of fungi. Fungi are diverse and adaptable, and they live in many different environments. Many fungi live in the soil, where their threadlike filaments fan out and tangle together into cords through the dirt, creating paths for interspecies interactions (interactions between different species). Many people think fungi are plants, but they are actually closer to animals. Fungi do not make their food from sunlight, as plants do. Like animals, fungi must find something to eat. Yet fungi obtain not only food for themselves but also make nutrients for other organisms. This occurs because fungi have digestion that is extracellular (taking place outside the cells). They excrete digestive acids outside their bodies to break down organic materials into nutrients. It is as if they had everted (inside out) stomachs, digesting food outside instead of inside their bodies. Nutrients are then absorbed into their cells, allowing the fungal body to grow-but also other species’ bodies. The reason there are plants growing on dry land rather than just in water is that over the course of Earth’s history, fungi have released digestive chemicals that break down rocks, making mineral nutrients available for plants. Fungi(together with bacteria) make the soil in which plants grow. Fungi also break down wood. Otherwise, dead trees would stack up in the forest forever. Fungi break them down into nutrients that can be recycled into new life. Fungi are thus world builders, shaping environments for themselves and others.
According to paragraph 1,which of the following is true of fungi’s special method of digestion?
Factual Information Questions事实信息题
AIt takes place in stomachs located in the fungal body.
BIt relies on digestive acids from plants to break down food.
CIt has enabled the growth of plants on land by breaking down rocks.
DIt has allowed many plants to stop relying on sunlight for food.
2
Mushrooms are the above-ground fruiting bodies of certain types of fungi. Fungi are diverse and adaptable, and they live in many different environments. Many fungi live in the soil, where their threadlike filaments fan out and tangle together into cords through the dirt, creating paths for interspecies interactions (interactions between different species). Many people think fungi are plants, but they are actually closer to animals. Fungi do not make their food from sunlight, as plants do. Like animals, fungi must find something to eat. Yet fungi obtain not only food for themselves but also make nutrients for other organisms. This occurs because fungi have digestion that is extracellular (taking place outside the cells). They excrete digestive acids outside their bodies to break down organic materials into nutrients. It is as if they had everted (inside out) stomachs, digesting food outside instead of inside their bodies. Nutrients are then absorbed into their cells, allowing the fungal body to grow-but also other species’ bodies. The reason there are plants growing on dry land rather than just in water is that over the course of Earth’s history, fungi have released digestive chemicals that break down rocks, making mineral nutrients available for plants. Fungi(together with bacteria) make the soil in which plants grow. Fungi also break down wood. Otherwise, dead trees would stack up in the forest forever. Fungi break them down into nutrients that can be recycled into new life. Fungi are thus world builders, shaping environments for themselves and others.
According to paragraph 1,all of the following are true of fungi EXCEPT:
Negative Factual Information Questions否定事实信息题
AThey can live in a number of different environments.
BThey live in close relationships with animals as well as with plants.
CThey help build the upper layer of earth in which plants grow.
DThey break down dead trees in forests.
3
Some fungi have learned to live in intimate associations with plants, and given enough time to adjust to the interspecies relations of a place, most plants enter into associations with fungi. Endophytic and endomycorrhizal fungi live inside plants. Many do not have fruiting bodies. We are likely never to see these fungi unless we peer inside plants with microscopes, yet most plants are thick with them. Ectomycorrhizal fungi, on the other hand, wrap themselves around the outsides of roots as well as penetrate between their cells. Many of the favorite mushrooms of people around the world-porcini, chanterelles, truffles, and matsutake-are the fruiting bodies of ectomycorrhizal fungi associated with plants. They are so delicious, and so difficult for humans to manipulate, because they thrive together with host trees. They come into being only through interspecies relations.
The word “intimate” in the passage is closest in meaning to
Vocabulary Questions词汇题
Acomplex
Bclose
Congoing
Dbeneficial
4
Some fungi have learned to live in intimate associations with plants, and given enough time to adjust to the interspecies relations of a place, most plants enter into associations with fungi. Endophytic and endomycorrhizal fungi live inside plants. Many do not have fruiting bodies. We are likely never to see these fungi unless we peer inside plants with microscopes, yet most plants are thick with them. Ectomycorrhizal fungi, on the other hand, wrap themselves around the outsides of roots as well as penetrate between their cells. Many of the favorite mushrooms of people around the world-porcini, chanterelles, truffles, and matsutake-are the fruiting bodies of ectomycorrhizal fungi associated with plants. They are so delicious, and so difficult for humans to manipulate, because they thrive together with host trees. They come into being only through interspecies relations.
According to paragraph 2,which of the following is NOT true of endophytic and endomycorrhizal fungi?
Negative Factual Information Questions否定事实信息题
AThey are common in trees also associated with ectomycorrhizal fungi.
BThey lack fruiting bodies in a large number of cases.
CMany plants are rich in them.
DThey cannot be seen without a microscope.
5
The term “mycorrhiza” is assembled from Greek words for “fungus” and “root”; fungi and plant roots become intimately entangled in mycorrhizal relations. Neither the fungus nor the plant can flourish without the activity of the other. From the fungal perspective, the goal is to get a good meal. The fungus extends its body into the host’s roots to remove some of the plant’s carbohydrates through specialized structures, made in the encounter. The fungus depends on this food, yet it is not entirely selfish. Fungi stimulate plant growth in two ways: first by getting plants more water, and second by making the nutrients of extracellular digestion available to plants. Plants get calcium, nitrogen, potassium, phosphorus, and other minerals through mycorrhiza. Forests, according to researcher Lisa Curran, occur only because of ectomycorrhizal fungi. By leaning on fungal companions, trees grow strong and numerous, making forests.
According to paragraph 3， as part of its mycorrhizal relationship with a plant, the fungus does which of the following?
Factual Information Questions事实信息题
AAllows the plant’s roots to extend into its own body
BAbsorbs water from the plant
CTakes carbohydrates from the plant
DRemoves calcium, nitrogen, potassium, and other minerals from the plant
6
Mutual benefits do not lead to perfect harmony. Sometimes the fungus parasitizes the root in one phase of the plant’s life cycle, exploiting the root for nutrients but giving nothing in return. Or if the plant has lots of nutrients, it may reject the fungus. A mycorrhizal fungus without a plant collaborator will die. But many ectomycorrhizas are not limited to one collaboration; the fungus forms a network across plants. In a forest, fungi connect not just trees of the same species, but often many species. If you cover a tree in the forest, depriving its leaves of light and thus food, its mycorrhizal associates may feed it from the carbohydrates of other trees in the network. Some commentators compare mycorrhizal networks to the Internet, writing of the “woodwide web,” as mycorhizas form an infrastructure of interspecies interconnection, carrying information across the forest. They also have some of the characteristics of a highway system. Soil microbes that would otherwise stay in the same place are able to travel in the channels and linkages of mycorrhizal interconnection. Some of these microbes are important for the removal of contaminants from soil. Mycorrhizal networks allow forests to respond to threats by, for example, mobilizing bacteria that degrade pollutants.
Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
Sentence Simplification Questions句子简化题
ASome commentators refer to mycorrhizal networks as the “woodwide web.”
BAn infrastructure of interspecies interconnection carries information across the forest.
CNetworks like the Internet are comparable to the infrastructure that some species create in the forest.
DMycorrhizal networks have been compared to the Internet because they create a forest-wide system of interconnected species.
7
Mutual benefits do not lead to perfect harmony. Sometimes the fungus parasitizes the root in one phase of the plant’s life cycle, exploiting the root for nutrients but giving nothing in return. Or if the plant has lots of nutrients, it may reject the fungus. A mycorrhizal fungus without a plant collaborator will die. But many ectomycorrhizas are not limited to one collaboration; the fungus forms a network across plants. In a forest, fungi connect not just trees of the same species, but often many species. If you cover a tree in the forest, depriving its leaves of light and thus food, its mycorrhizal associates may feed it from the carbohydrates of other trees in the network. Some commentators compare mycorrhizal networks to the Internet, writing of the “woodwide web,” as mycorhizas form an infrastructure of interspecies interconnection, carrying information across the forest. They also have some of the characteristics of a highway system. Soil microbes that would otherwise stay in the same place are able to travel in the channels and linkages of mycorrhizal interconnection. Some of these microbes are important for the removal of contaminants from soil. Mycorrhizal networks allow forests to respond to threats by, for example, mobilizing bacteria that degrade pollutants.
In paragraph 4,why does the author note that mycorrhizal networks”have some of the characteristics of a highway system”?
Rhetorical Purpose Questions修辞目的题
ATo argue that it is inaccurate to compare mycorrhizal networks to the Internet
BTo provide evidence showing that microbes can remove soil contaminants
CTo explain why bacteria are the type of microbes that forests mobilize when threatened
DTo explain how microbes in soil are able to move to where they are helpful
8
Mutual benefits do not lead to perfect harmony. Sometimes the fungus parasitizes the root in one phase of the plant’s life cycle, exploiting the root for nutrients but giving nothing in return. Or if the plant has lots of nutrients, it may reject the fungus. A mycorrhizal fungus without a plant collaborator will die. But many ectomycorrhizas are not limited to one collaboration; the fungus forms a network across plants. In a forest, fungi connect not just trees of the same species, but often many species. If you cover a tree in the forest, depriving its leaves of light and thus food, its mycorrhizal associates may feed it from the carbohydrates of other trees in the network. Some commentators compare mycorrhizal networks to the Internet, writing of the “woodwide web,” as mycorhizas form an infrastructure of interspecies interconnection, carrying information across the forest. They also have some of the characteristics of a highway system. Soil microbes that would otherwise stay in the same place are able to travel in the channels and linkages of mycorrhizal interconnection. Some of these microbes are important for the removal of contaminants from soil. Mycorrhizal networks allow forests to respond to threats by, for example, mobilizing bacteria that degrade pollutants.
Which of the following can be inferred from paragraph 4 about trees that are connected to one another through a network of ectomycorrhizal fungi?
Inference Questions推理题
AThey are more likely to die in the early stages of life than are trees living independently of such networks.
BThey might be able to survive even if they cannot produce enough carbohydrates for their own use.
CThey are more likely to produce nutrients for themselves than trees living independently of such networks.
DThey commonly live in areas that receive comparatively little sunlight.
9
Mutual benefits do not lead to perfect harmony. [■] Sometimes the fungus parasitizes the root in one phase of the plant’s life cycle, exploiting the root for nutrients but giving nothing in return. [■] Or if the plant has lots of nutrients, it may reject the fungus. [■] A mycorrhizal fungus without a plant collaborator will die. [■] But many ectomycorrhizas are not limited to one collaboration; the fungus forms a network across plants. In a forest, fungi connect not just trees of the same species, but often many species. If you cover a tree in the forest, depriving its leaves of light and thus food, its mycorrhizal associates may feed it from the carbohydrates of other trees in the network. Some commentators compare mycorrhizal networks to the Internet, writing of the “woodwide web,” as mycorhizas form an infrastructure of interspecies interconnection, carrying information across the forest. They also have some of the characteristics of a highway system. Soil microbes that would otherwise stay in the same place are able to travel in the channels and linkages of mycorrhizal interconnection. Some of these microbes are important for the removal of contaminants from soil. Mycorrhizal networks allow forests to respond to threats by, for example, mobilizing bacteria that degrade pollutants.
Look at the four squaresthat indicate where the following sentence could be added to the passage
This response can be dangerous for the fungus.Insert Text Questions句子插入题
Where would the sentence best fit？Click on a square sentence to the passage.
10
Fungi play an important role in forests.
Prose Summary Questions概要小结题
Select 3 answers
AThroughout the course of Earth’s history, fungi have spread faster and wider than any other type of organism, including bacteria.
BWhile some fungi are limited to forming associations with a single kind of plant, most fungi form associations with a wide variety of plant species in forests.
CMycorrhiza plant-fungi associations benefit both plants and fungi, which is why most plants form associations with fungi and why fungi are so dependent on plants for their survival.
DFungi are similar to animals in certain respects, but they are actually more like plants in that they get their nutrients from long threadlike filaments that fan out and tangle through the dirt like roots.
EUsing extracellular digestion, fungi produce acids that break down materials and through this process release nutrients that can be used by trees and other plants.
FMycorrhiza plant-fungi associations form vast networks in forests, making it possible for carbohydrates, minerals, microbes, and chemical messages to pass among connected organisms.
