Unit 3 Conservation Lesson 1 The Sixth Extinction 课件(共36张PPT，内镶嵌视频)-北师大版(2019)选择性必修第一册

(共36张PPT)
Unit 3
n. a situation in which sth. no longer exists
灭绝, 消亡
To read and talk about conservation
To read for general understanding
To read for specific information and understand words in context
To learn about and practise the adjectives and nouns
To express solutions for environmental problems
How much do you know about extinction
1
Choose the option based on your knowledge.
1 How many times up to today has life on Earth almost died out
a Once. b Five times. c More than 10 times.
2 About what percent of all species on Earth became extinct during the mass extinction known as the “Great Dying”
a Less than 10%. b Nearly 50%. c More than 90%.
3 What do scientists think will cause the next mass extinction
a Human activity. b Natural causes. c Unknown reasons.
Read a text about extinction. Then check your answers in Activity 1.
2
1 How many times up to today has life on Earth almost died out
a Once. b Five times. c More than 10 times.
2 About what percent of all species on Earth became extinct during the mass extinction known as the “Great Dying”
a Less than 10%. b Nearly 50%. c More than 90%.
3 What do scientists think will cause the next mass extinction
a Human activity. b Natural causes. c Unknown reasons.
When: about 440 million years ago
Size of the Extinction:
Up to 85% of all living species eliminated
Suspected Cause or Causes:
Continental drift and subsequent climate change
When: about 365 million years ago
Size of the Extinction:
Nearly 80% of all living species eliminated
Suspected Cause or Causes:
Lack of oxygen in the oceans, quick cooling of air temperatures, volcanic eruptions and/or meteor (流星) strikes
When: about 250 million years ago
Size of the Extinction:
An estimated 96% of all living species eliminated
Suspected Cause or Causes:
Unknown—possibly asteroid (小行星) strikes, volcanic activity, climate change, and microbes (微生物)
When: about 200 million years ago
Size of the Extinction:
More than half of all living species eliminated
Suspected Cause or Causes:
Major volcanic activity with basalt (玄武岩) flooding, global climate change, and changing pH and sea levels of the oceans
When: about 65 million years ago
Size of the Extinction:
Nearly 75% of all living species eliminated
Suspected Cause or Causes:
Extreme asteroid or meteor impact
wipe out
species
a group of animals or plants whose members are similar and can breed together to produce young animals or plants
to stop existing
to destroy or remove pletely
affecting or involving a large number of people or things
to say or think that someone or something is responsible for something bad
different from what is usual or normal
mass
Read and match.
die out
unusual
blame
affect
endangered
(of a young bird, fish, insect, etc.) to come out of an egg
to make sb./sth. return to its former state or condition
to produce a change in sb./sth.
in danger of being harmed or lost
of many different types
to become or make sth become smaller in size, number, etc
hatch
restore
varied
decrease
Extinction
Meaning of extinction
__________________
__________________
The number of extinctions that have occurred so far
______________________________________
Two notable extinctions and their consequences
_____________
Main reasons that cause extinctions
_____________
How to avoid the sixth mass extinction
_____________
Read the plete the notes. Then talk about the different aspects of extinctions.
entire species are wiped out
five times
3
Main reasons that cause extinctions
________________________________________________________________________________________________________________
How to avoid the sixth mass extinction
__________________________________________________________________________________________________________________________________________________________________________
volcanic eruptions, asteroids hitting the Earth from space, changes in sea levels, the decrease of oxygen content of the sea, global warming
change the way we live: take steps to save endangered species; change how we work and travel by using cleaner, more natural sources of energy; improve our farming methods to reduce water, air and land pollution
Two notable extinctions and their consequences
_______________________________________________________________________________________________________________________________________
the third mass extinction, killed 90% to 96% of all species; the fifth event, which occurred 66 million years ago, caused the death of the dinosaurs
Read the text and decide whether these statements are true (T) of false (F).
1. More than 96% of all species that ever lived on the earth are extinct.
2. Dinosaurs were wiped out because of the decrease of the oxygen content in the “Great Dying”.
3. In 1980, there were only 250 black robins left in the world.
4. It is not too late for us to take action to do something to protect our planet.
F
F
F
T
Read again. Answer the questions.
1. What did scientists find out in 2015
2. Why does the writer think the sixth mass extinction will come
They found that human activity is causing species to die out 1,000 times faster than normal.
Because human activity has negatively affected all other species on Earth, including animals and plants.
4
3. Why does the writer believe we'll probably die out if 75% of the Earth's species die out
Because we humans depend on so many species for our survival, and our world and our lives depended on the balance in nature between animals and plants.
4. What did people do in the case study to protect black robins Which claim(s) did the case study support in the text
People protected Old Blue’s eggs, helped them to hatch, and took care of the chicks. People are restoring their habitats and removing small animals that hunt them, such as mice and cats from the islands where they live. The case study showed that even in desperate situations, we can do something to help. In short, it’s never too late.
Extinctions, where entire species are wiped out, are not unusual in our Earth’s history. In fact, over 90 percent of all species that ever lived are now extinct. In the last 500 million years, there have been five times when life on Earth has almost ended. These include the third mass extinction, known as the “Great Dying”, which killed 90% to 96% of all species. And the fifth event, which occurred 66 million years ago, caused the death of the dinosaurs. The reasons for extinctions are varied. According to scientists, they include volcanic eruptions, asteroids hitting the Earth from space, changes in sea levels, the decrease of the oxygen content of the sea and global warming. Many scientists say we are now entering the Earth’s sixth mass extinction.
This time, human activity will be to blame.
物种灭绝（即整个物种被彻底消灭的情况）在地球历史上并不罕见。
（非限定从）
大灭绝
物种灭绝的原因多种多样。
…… 的减少
这一次，人类活动将是原因/(罪魁祸首)。
Although it is not unusual for species to die out naturally, the rate at which this is now happening is cause for concern. A 2015 study by scientists who were based at Brown University and Duke University in the US, looked at how quickly species die out due to natural causes, that is, the“background extinction rate”. They found that human activity is causing species to die out 1,000 times faster than normal. There is a long list of reasons why so many species are dying out: air and water pollution, forests being destroyed, factory farming and overfishing. It is clear that human activity has negatively affected all other species on Earth, including animals and plants.
尽管物种自然灭绝并不罕见，
但现在物种灭绝的速度却令人担忧。（定从）
显然
人类活动对地球上所有其他物种都产生了负面影响，
包括动物和植物。
If a sixth mass extinction occurs, scientists who have studied the issue believe that up to three quarters of all species on Earth could die out. Of course, as we humans depend on so many species for our survival, we would also be at risk of dying out. Our world and our lives depend on the balance in nature between animals and plants. Without forests, we would have no air to breathe, and without clean water we would be unable to survive.
面临灭绝的危险
(虚拟语气)
没有森林，我们就没有呼吸的空气,
没有干净的水，我们就无法生存。
Can a sixth extinction be avoided Experts say that it is not yet too late, if we take action now. This would mean we have to significantly change the way we live. For example, we need to take steps to save endangered species, including setting up special areas where plants and animals can be protected. We need to change how we work and travel by using cleaner, more natural sources of energy, such as wind and solar energy. We also need to improve our farming methods to reduce water, air and land pollution. In short, if we want to survive, we need to stop destroying the planet that we live on and start to protect it.
我们需要采取措施拯救濒危物种，
包括建立可以保护动植物的特殊区域。（定从）
太阳能
改进我们的耕作方法，以减少水、空气和土地污染。
停止破坏我们赖以生存的地球，开始保护它。
1. Use different coloured pens to highlight at least one example for each of the four elements listed below in different colours. Then find out:
(1) What typical language is used
facts opinions / predictions
reasons solutions
5
Facts: over 90% of all species that ever lived are extinct; the "Great Dying", which killed 90% to 96% of all species; human activity is causing species to die out 1,000 times faster than normal.
Reasons: air and water pollution, forests being destroyed, factory farming and overfishing are causing species to die out; without forests, we would have no air to breathe and without clean water we would be unable to survive.
Solutions: we need to take steps to save endangered species, including setting up special areas where plants and animals can be protected; we need to change how we work and travel ...; we also need to improve our farming methods...
Opinions/predictions: many scientists say we are now entering the Earth's sixth mass extinction; scientists believe that up to three quarters of all species on Earth could die out.
(2) What text type is this piece of writing
(3) What is its communicative purpose
This piece of writing is an exposition.
Its purpose is to explain what the sixth extinction is and its effects and call on people to take action to prevent it from happening.
2. What ways of argument does the writer use to convince readers Are you convinced Why or why not
The writer uses ways such as citing ideas from experts or authorities, giving examples and using data. I believe that if we take action now it is not too late to save other species from extinction. The black robin was saved from extinction when only five birds remained, so I think it is possible to save any species if we act right now.
1. What have you learned from the story of the black robin Share your opinion with your partner.
2. Are there any factories polluting your neighbourhood If so, tell your group members how they affect your everyday life.
Use the adjectives and nouns to make meaningful expressions. Then use each expression to make a sentence.
entire
endangered
significant
natural
mass
solar
change
resource
extinction
species
energy
animal
entire species
endangered animals
significant changes
natural resources
mass extinction
solar energy
6
1. Each time it drained (流光), it caused entire species of sea plants and creatures to die off.
2. The original research was about the origin of a kind of endangered animal.
3. I think that's quite a significant change.
4. Soil water is an important natural resource.
5. This is the story of wildlife conservation in the age of mass extinction.
6. Solar energy is a new kind of source of energy.
Complete the paragraph about extinctions using the correct form of the phrases below.
die out be known as have affected depend on
wipe out take steps take action set up take care of
In the last 500 million years, there have been five mass extinction events on Earth. In the third event, which 1_____________ the "Great Dying, 90% to 96% of all species 2__________.
is known as
died out
7
Of course, species died out due to many causes. But nowadays, human activity 3____________ all types of species that we 4__________ for living. We need to 5__________ to avoid the sixth mass extinction. We should 6__________ to save endangered animals and plants, and 7__________ special areas to 8___________ them before the next extinction comes that may 9___________ the entire species.
take steps
take action
set up
take care of
wipe out
die out be known as have affected depend on
wipe out take steps take action set up take care of
has affected
depend on
Write a passage about “What can we do to save the endangered animals” in 120 words.