Approximately what percentage of the earth’s surface do lichens occupy?

Learning Goal: I’m working on a botany multi-part question and need an explanation and answer to help me learn.Requirements:NO OUTSIDE SOURCES TO ANSWER QUESTIONSSpell CheckFull sentencesInstructions:Use the summary below as well as the small pdf attached about lichens to answer these 7 questions.Summary:Lichens are unusual creatures. Lichen is not a single organism the way most other living things are, but rather it is a combination of two organisms that live together intimately. Most of the lichen is composed of fungal filaments, but living among the filaments are algal cells, usually from a green alga or a cyanobacterium. In many cases, the fungus and the alga which together make the lichen may each be found living in nature without its partner, but many other lichens include a fungus that cannot survive on its own -it has become dependent on its algal partner for survival. In all cases though, the appearance of the fungus in the lichen is quite different from its morphology as a separately growing individual. The true identity of lichens as symbiotic associations of two different organisms was first proposed by Beatrix Potter, who is best remembered for her children’s books about Peter Rabbit. In addition to her books, she spent time studying and drawing lichens. Her illustrations are still appreciated for their detailed and accurate portrayal of these bizarre organisms. In combination, the lichen symbionts produce a growth form that is unlike either fungi or algae growing alone. Three growth forms are easy to recognize:Lichen are very sensitive to air quality, and even slightly increased levels of ozone and sulfur dioxides will reduce their metabolic activity. In fact, each of the three major types of lichen is sensitive to differing concentrations of air pollutants. Fruticose lichen is the most sensitive to air quality. In the cases of highly polluted air or air regularly exposed to pollutants, the fruticose will NOT be present. Likewise, crustose is the most resistant to pollutants. It can often be found in areas with elevated levels of pollutants. Finally, foliose is moderately tolerant of air pollutants. The presence of each of these lichen in varying numbers and concentrations can provide substantial relative indicators of air quality.Questions:
What is a lichen?
What type of symbiotic relationship does a lichen demonstrate?
Approximately what percentage of the earth’s surface do lichens occupy?
Identify two pollutants that lichens are sensitive to.
Relate lichens to air quality.
Lichen are often the first living organisms to appear in a disturbed area. Why would this be the case?
Lichen prefers to grow in direct sunlight even though it is a fungi-like organism. Why do think they prefer this?

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