A Lichen Partnership
Written by Studio AM.
Your result
- Words per minute
- Score
- Pace
Words per minute mean something only with the score beside them. They describe this passage on this read. With fewer than 3 right, try the next slower pace.
Choose a pace and select Start. The passage is paced and timed, then the questions check what you understood. How pace mode works
Reading time 0:00
The grey-green crust on an old stone wall may look like a plant. Often it is a lichen: a close partnership between a fungus and a partner that makes food using sunlight. That partner may be an alga, a type of bacterium called a cyanobacterium, or both.
The partners have different roles. The fungus forms most of the body. It holds moisture and can shield the cells inside from strong light. The alga or cyanobacterium makes sugars through photosynthesis. This arrangement helps lichens grow on surfaces such as bark and bare rock, where conditions can be difficult for other organisms.
Lichens take in water and substances from their surroundings. Exposure to some air pollutants can harm sensitive species, while other species tolerate more pollution. Changes in which lichens grow at a site can therefore help researchers study air quality.
The evidence needs care. A missing lichen does not by itself prove the air is polluted. Moisture, temperature and the surface available for growth also matter. Researchers compare species and conditions before drawing a conclusion.
The passage is hidden while you answer. It comes back with your result.
Questions
Choose an answer. The explanation appears after you answer.
-
Question 1 of 4
Which sentence best states the main idea?
The answer is B: A lichen's partners support its growth, and its response to air can help researchers study pollution.
The passage explains the partners' roles and how lichens can provide evidence about air quality when other conditions are considered.
-
Question 2 of 4
According to the passage, what does the fungus contribute to the partnership?
The answer is C: It forms most of the body, holds moisture and helps protect its partner.
The fungus provides much of the structure and protection. The alga or cyanobacterium makes sugars using sunlight.
-
Question 3 of 4
A lichen disappears from a park. What is a reasonable next step?
The answer is A: Check air quality alongside moisture, temperature and growing surfaces.
The passage identifies pollution as one possible influence, not the only one. Comparing several conditions helps avoid a premature conclusion.
-
Question 4 of 4
In this passage, 'shield' means:
The answer is D: protect from something harmful
The fungus shields its partner from strong light, that is, it protects the alga from light that would harm it.
Score: none answered yet.