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人教2003课标版《Using LanguageⅡ》新课标PPT课件优质课下载
I can see a strawberry plant producing runners in a natural form of cloning.
Who cut the stem off the plant?
A gardener. The gardener is going to put it into a pot to produce another plant. He is actually making a copy of the plant.
What do you know about twins?
There are twins of the same sex and those of different sexes. The twins here are identical in sex and appearance and are good examples of natural clones. They carry the same genetic information. The fertilized egg has split into two while inside the mother, and so produced two identical human babies.
Are the following clones the same? If not, what is the difference?
No. The first two are man-made clones.
The rest two are natural clones.
Questions about cloning:
1. What is a clone?
A clone is an animal or plant produced naturally or artificially from the cells of another animal or plant and is exactly the same as it.
2. How is a clone produced?
The cloning of plants is simple and
relatively easy. It can be done by taking cuttings (man-made cloning) or letting the plant produce its own runners (natural cloning). The cloning of animals is more complicated. It was not achieved until 1996 and is fully explained in the first reading.
3. What benefits can humans gain from cloning?
1) Medical cloning can help cure serious illnesses that ruin one’s quality of life (such as Parkinson’s disease帕金森症 or Alzheimer’s disease老年痴呆症).
2) It can help infertile people have babies.
4. What problems may arise when humans are cloned?
1) People may want to clone themselves so they can live forever.
2) People may want to clone dead children.
3) People may want to clone their favorite pets.
The text is mainly about the 1. _________ of animal cloning and the life of Dolly the sheep, as well as the reasons why cloning is still 2. ___________.
controversial
procedure
Read the text quickly and complete its main idea.