Looking More Closely at Lichens
Written by Studio AM.
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A lichen can look like a crust, a leaf or a tiny branching shrub. It is not a single plant. Its familiar partners are a fungus and an alga or cyanobacterium that makes food using sunlight. Other microbes can live within it too.
In 2016, researchers reported yeasts in the outer layers of several groups of lichens. Yeasts are fungi, but these belonged to a different fungal group from the main partner. Genetic analysis helped identify them, and microscopy showed where their cells occurred. The finding added detail to the usual two-part description rather than replacing it with a rule that every lichen has exactly three partners.
Researchers also study lichens at a different scale: their pace of growth. Some crust-forming kinds spread very slowly, but growth varies with the species and conditions. Measuring the same patch over time gives better evidence than judging its age from its size alone.
Both kinds of work show the value of careful observation. A closer view can reveal organisms inside a lichen, while repeated measurements reveal changes that are hard to notice during a single visit.
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Questions
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Question 1 of 4
Which statement best sums up the passage?
The answer is B: Closer examination and repeated measurements reveal more about lichen partners and growth.
The passage links two approaches: examining cells and measuring growth over time. Both reveal information a quick look would miss.
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Question 2 of 4
What did the researchers report in 2016?
The answer is C: Yeasts occurred in the outer layers of several groups of lichens.
Genetic analysis and microscopy revealed yeasts in the outer layers of the lichens studied. The finding was not an exact count for every lichen.
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Question 3 of 4
Why might two lichen patches of the same size have different ages?
The answer is D: Species and conditions can produce different growth rates.
Size reflects both time and growth rate. Since growth rates vary, equal size does not guarantee equal age.
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Question 4 of 4
What does 'pace' mean in the paragraph about growth?
The answer is B: the speed at which something happens
The paragraph discusses how slowly lichens spread and how that rate varies. 'Pace' means speed.
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