Read the following passage.
A. On rock outcrops in the boreal forest and across the Arctic tundra, the ground is often covered with pale, branching reindeer lichens. One of them, the star-tipped reindeer lichen, grows in every province and territory and forms rounded mounds that look like little heads of cauliflower; on dry days it crunches underfoot. In an online vote held by the Canadian Museum of Nature, it was Canadians' top choice for a national lichen. Although it looks like a plant, a lichen is a partnership between a fungus and green algae or cyanobacteria, and perhaps 2,500 kinds are found in Canada.
B. Reindeer lichens grow upward at the tip while the base slowly dies, forming dense mats about 4 to 12 centimetres tall. Their growth is slow: average rates of 4.8 to 11.1 millimetres a year have been reported, along with average ages of more than 100 years. Because they can absorb water directly from the air, they can take over soils that are too dry, and often too cold, for plants with roots. When a caribou steps on a mound, small spiky pieces break off, catch in its hair and are carried to a new place.
C. Barren-ground caribou depend on lichens for most of their winter diet, and caribou are one of the few mammals able to feed on and digest them. Caribou find lichens under the snow by their excellent sense of smell and dig them out with their broad hooves. In caribou sampled from October to April in the Northwest Territories, northern Saskatchewan and northern Manitoba, these lichens formed 40.5 to 62.5 per cent of stomach contents by dry weight. Lichens supply energy but little protein, so in spring caribou switch to fresh green plants.
D. Fire and heavy grazing both strip away lichen cover, and its return is still being studied. In jack pine woodlands of northern Saskatchewan and northeastern Alberta, reindeer lichens began to reestablish within 1 to 3 years after fire, and in one Northwest Territories study they dominated the ground in forests burned 20 to 60 years earlier. Heavy trampling by large numbers of caribou can set recovery back by many decades. A researcher who studied caribou in Nunavut suggested that fire severity and grazing intensity may matter more than time since the fire. It is also often hard to tell whether lichens on a burned site grew from pieces blown in from elsewhere or from small pieces that survived.
E. Not given in any of the above paragraphs.
Decide which paragraph, A to D, has the information given in each statement below. Select E if the information is not given in any of the paragraphs.
AI explanationShows the answer. Tap to open.
Correct Answer: B
Why this is correct: Look at Paragraph B. Reindeer lichens have been reported with average ages of more than 100 years. More than 100 years is more than a century.
Passage Reference: Their growth is slow: average rates of 4.8 to 11.1 millimetres a year have been reported, along with average ages of more than 100 years.
Tips: Many time spans appear in this text. Check which one is about how long a lichen lives, and whether it passes a century.
Why the other options are wrong:
- A: Paragraph A describes how the lichens look and what they are made of. It does not say how old they get.
- C: Paragraph C gives percentages from caribou stomachs. The age of the lichens is not there.
- D: In Paragraph D, trampling can delay recovery by many decades. That is about growing back, not how long a lichen lives.
- E: The average age of more than 100 years is reported in Paragraph B.
Correct Answer: A
Passage Reference: Although it looks like a plant, a lichen is a partnership between a fungus and green algae or cyanobacteria, and perhaps 2,500 kinds are found in Canada.
Why this is correct: Paragraph A explains what a lichen is. It looks like a plant, but it is a partnership between a fungus and green algae or cyanobacteria. That means two kinds of living things joined together.
Tips: Find where the text explains what a lichen is. Then check that it names two different living things.
Why the other options are wrong:
- B: Paragraph B explains how lichens grow and spread. It does not say what they are made of.
- C: Paragraph C is about caribou eating lichens. The parts of a lichen are not named.
- D: Paragraph D deals with damage from fire and grazing. It does not explain what a lichen is.
- E: The partnership between a fungus and algae or cyanobacteria is explained in Paragraph A.
Correct Answer: E
Passage Reference: One of them, the star-tipped reindeer lichen, grows in every province and territory and forms rounded mounds that look like little heads of cauliflower; on dry days it crunches underfoot.
Why this is correct: Paragraph A says the star-tipped reindeer lichen grows in every province and territory. It was also the top choice in the museum's vote. But growing everywhere is not the same as being the most plentiful. The text never compares its amount with other lichens.
Tips: Being found in many places does not mean being the most common. Look for a real comparison.
Why the other options are wrong:
- A: You might think of Paragraph A because it names the contest winner. It says where the lichen grows, but it never ranks it by amount.
- B: Paragraph B gives growth rates and ages for reindeer lichens as a group. It does not rank the kinds.
- C: Paragraph C tells you how much of a caribou's food is lichen. It does not say which lichen is most common.
- D: Paragraph D explains how lichens come back after fire. It makes no comparison between kinds.
Correct Answer: C
Passage Reference: Caribou find lichens under the snow by their excellent sense of smell and dig them out with their broad hooves.
Why this is correct: The clue is in Paragraph C. Caribou find lichens under the snow with their excellent sense of smell. Scent means smell, and the lichens are the hidden food.
Tips: Caribou come up in several places. Look for how they locate food beneath the snow, and check that scent is the reason.
Why the other options are wrong:
- A: Paragraph A describes lichens that crunch underfoot on dry days. It does not say how caribou find them.
- B: Paragraph B has a caribou stepping on a mound, which spreads the lichen. Smell and snow are not mentioned.
- D: Paragraph D shows caribou trampling lichens. It does not describe them searching for food in winter.
- E: Paragraph C describes caribou finding lichens under the snow by smell.
Correct Answer: D
Passage Reference: In jack pine woodlands of northern Saskatchewan and northeastern Alberta, reindeer lichens began to reestablish within 1 to 3 years after fire, and in one Northwest Territories study they dominated the ground in forests burned 20 to 60 years earlier.
Why this is correct: Paragraph D describes jack pine woodlands of northern Saskatchewan and northeastern Alberta. There, reindeer lichens began to come back within 1 to 3 years after fire. One to three years is a few years.
Tips: Look for lichens coming back after flames. Then check how long that took: only a few years, or many?
Why the other options are wrong:
- A: Paragraph A describes lichens on rocks in the forest and on the tundra. Fire is not part of it.
- B: Paragraph B gives yearly growth in millimetres. It does not mention fire.
- C: Paragraph C names northern Saskatchewan as a place where caribou were sampled. It is not about lichens growing back after fire.
- E: Lichens returning within 1 to 3 years after fire are reported in Paragraph D.
Correct Answer: B
Passage Reference: Because they can absorb water directly from the air, they can take over soils that are too dry, and often too cold, for plants with roots.
Why this is correct: Look closely at Paragraph B. Reindeer lichens can absorb water directly from the air. Because of this, they can take over soils too dry for plants with roots. Moisture from the atmosphere is water from the air.
Tips: Ask yourself why these lichens can live on very dry ground. Check that the reason is how they take in moisture.
Why the other options are wrong:
- A: Paragraph A tells you a lichen looks like a plant but is really a partnership. It does not explain how lichens get water.
- C: Paragraph C mentions caribou switching to green plants in spring. That is about food, not water or soil.
- D: Paragraph D describes lichens growing back on burned ground. Water from the air is not mentioned.
- E: Paragraph B explains that lichens take water from the air and can live on dry soils.
Correct Answer: D
Passage Reference: Heavy trampling by large numbers of caribou can set recovery back by many decades.
Why this is correct: Paragraph D gives this idea. Heavy trampling by large numbers of caribou can set recovery back by many decades. Trampling means walking over something again and again, and setting recovery back means it takes longer.
Tips: Paragraph B also has a caribou stepping on lichen. Ask if the result is spreading or damage.
Why the other options are wrong:
- A: In Paragraph A, the lichen crunches underfoot on dry days. It does not say this slows its recovery.
- B: Look at Paragraph B. A caribou stepping on a mound there helps the lichen spread. That is the opposite of harm.
- C: Paragraph C describes caribou digging lichens out of the snow to eat. It is not about damage from many animals walking.
- E: The damage done when many caribou trample the lichen is covered in Paragraph D.
Correct Answer: E
Passage Reference: In caribou sampled from October to April in the Northwest Territories, northern Saskatchewan and northern Manitoba, these lichens formed 40.5 to 62.5 per cent of stomach contents by dry weight.
Why this is correct: Paragraph C says lichens make up most of the caribou's winter food. It gives their share of stomach contents, 40.5 to 62.5 per cent. That is a share, not an amount eaten each day.
Tips: A percentage is not a weight. Check if any paragraph gives kilograms.
Why the other options are wrong:
- A: Paragraph A describes how the lichen looks. It has no figures about what caribou eat.
- B: Paragraph B gives a growth rate in millimetres a year. It does not say how much a caribou eats.
- C: Be careful here. Paragraph C covers winter feeding, but it uses a percentage of stomach contents, not kilograms a day.
- D: Paragraph D talks about grazing after fires. It gives no daily amount of food.
Correct Answer: D
Passage Reference: It is also often hard to tell whether lichens on a burned site grew from pieces blown in from elsewhere or from small pieces that survived.
Why this is correct: Paragraph D ends on this doubt. It is often hard to tell where lichens on a burned site came from. They may grow from pieces blown in or from small pieces that survived. Hard to tell means scientists are unsure.
Tips: Think about new growth after a fire. Does the text say where it comes from, or does it say this is still unclear?
Why the other options are wrong:
- A: Paragraph A describes the lichen as it looks today. Fire is not mentioned.
- B: Paragraph B shows pieces caught in caribou hair starting new lichens. That is a known way to spread, not an open question about fire.
- C: Paragraph C is about what caribou eat in winter. It does not ask where new lichens come from.
- E: The open question about where lichens on burned ground come from ends Paragraph D.
The rest of this explanation is for members. Sign in free to read why the other options are wrong, key words and tips.
Sign in to read the full explanation