中华人民共和国教育部主管,北京师范大学主办,ISSN:1002-6541/CN11-1318/G4

(中学篇)2020年第08期:英语分级群文阅读教学中批判性思维的培养(四川:周霜)一文涉及的教学内容

 
Passage 1
 
Jurassic Park Scientific Fact or Hollywood Fiction? 
 
Steven Spielberg's successful sci-fi adventure film follows two dinosaur experts — Dr Alan and Dr Ellie Sattler — as they are invited by the eccentric millionaire John Hammond to visit his new amusement park on an island off Costa Rica before it opens to the public. By cloning DNA taken from prehistoric mosquitoes, Hammond has created living dinosaurs for his new Jurassic Park. Accompanied by Hammond's two grandchildren, they are sent on a tour through Jurassic Park in computer-controlled cars. But a tropical storm hits the island, knocking out the power supply, and an employee destroys the security system so that he can steal dinosaur embryos and sell them. The dinosaurs start to get out of control …
 
So, since it is possible to clone sheep, is it possible to clone dinosaurs? Or is this just Hollywood? First, any DNA that has been taken from a preserved mosquito is only 40 million years old. Dinosaurs are at least 60 million years old, so even if any DNA was found, the mosquitoes need to be much older, and as far as we know, mosquitoes that old do not exist.
 
Second, although it is possible to find preserved mosquitoes, only one male has been recovered. In fact, only females can absorb the DNA of another creature. Also, there is no way of knowing if the DNA was from a dinosaur or not. Since there has been no previous discovery of dinosaurs, there is nothing to compare the new sample with.
 
Thirdly, dinosaur DNA would not be intact after the long period of time since their extinction. When life ends, DNA breaks down and does not repair itself.
 
Many questions also arise in the cloning of dinosaurs. Some of these questions are: What will be needed to raise a baby dinosaur from childhood successfully? What kinds of conditions do dinosaurs need to survive? What are the diets of dinosaurs? What kinds of care would dinosaurs need in their adult lives? What would be done to protect humans from dinosaurs and vice versa? What ethical and human rights issues are raised by cloning?
 
So cloning dinosaurs seems scientifically impossible. The world is not ready for it and the materials that are needed are not yet available. Even if it was possible to bring dinosaurs back to life they probably could not survive in the present day environment. Temperature, air, disease, and plants are all different today than in the era of dinosaurs. Dinosaurs are used to a completely different world and would find great difficulty living here. The only place that dinosaurs seem to exist today is in Hollywood.
  
 
Passage 2
 
To Clone or not to Clone: The Ethical Question
 
Defining Human Cloning
 
When speaking of human cloning, what is meant? Different groups and organizations define it differently. To use a specific definition, the American Medical Association (AMA) defined cloning as the production of genetically identical organisms via somatic cell nuclear transfer. In other words, cloning is the method of producing a baby that has the same genes as its parent. However, many groups have used a broader definition of cloning. They include the production of tissues and organs through growing cells or tissues in cultures along with the actual producing of embryos to be born.  
 
One must understand that cloning does not produce an exact copy of the person being cloned. What cloning does, is that it copies the DNA/genes of the person and creates a duplicate genetically. The person will not be a Xerox copy. He or she will grow up in a different environment than the clone, with different experiences and different opportunities. Genetics does not wholly define a person and the personality.
 
Let Us Clone
 
Cloning can be used to help benefit those that are sterile and cannot have children through the normal, natural way. It is the desire of most couples to have children and when it is impossible to bare children of your own, some are willing to do anything to have a child. Cloning will allow them to have a child or many children that have the genetic pattern of one of the parents.
 
Through cloning, research can progress. It is hard to say what we can learn from cloning if cloning is not allowed. We possibly can learn more about cell differentiation. We can learn enough to produce human organs without having to produce human beings. We may develop technology to allow easier genetic testing and fixing problems such as spinal cord injuries, cancer, Tay-Sachs disease, and many more.
 
Cloning organs for organ transplants is one of the major practical reasons that cloning should be allowed. There is always a high demand for organs. Some argue for the cloning of humans to create spare body parts. Others talk of just wanting to clone an organ to replace a defective organ.
 
We shall Not Clone
 
One of the main goals of the government is to protect human life. Some people want the government to regulate cloning and not allow it. Michigan's government believes this and became the first government to place a ban on cloning. 
 
Cloning would lead to the loss of individuality because one's genetic predispositions and conditions would be known. If raised by a clone-parent or as a sibling to the cloned, one may have great expectations to live up to. However, the human clones could differ greatly in personality and even grow up with different conditions than the cloned. Even monozygotic twins differ. This could be a great stress to the clone and possibly even the loss of ability to choose for itself.
 
Technology as we presently know it will not effectively support the cloning of humans. As mentioned before, the success rate was quite low when cloning Dolly. Only one of the 277 tries succeeded. The same problems of the difficulty of having the fertilized egg implant parallels with that in in vitro fertilization. Technology has not yet been able to provide an answer to this problem.
 
The fear that clones will be treated as second-class citizens is also present. If a clone is created to act as bone marrow or kidney donor, the question arises if they would be treated like the first child? Would the parents even love this child the same? If not, this would lead to negative self-esteem and/or other physiological problems. 
 
There is also the fear that some would want to clone people to create large armies of the same soldier or even produce large amounts of workers. This would also lead to the creation of a second and lower class for clones.
 
My Personal Recommendation
 
I personally think that the world of genetics is fascinating, but after learning of what is now possible through technology, I changed my mind. I see cloning as a wonderful advancement in technology and knowledge. I do not think it should be used to reproduce humans though. I do not believe that we should try to develop other ways beside the natural way to bring life into this world. 
 
Cloning falls under a different category that clones human beings. I think it would be advantageous to science and medicine to clone organs.  
 
 
Passage 3  
 
Cloning and DNA 
 
Many people think that the science of genetics and cloning is recent. It's certainly true that in 1953, Watson and Crick, two scientists at Cambridge University, England, discovered the structure of the acid DNA — a transparent twisting ladder made of the fundamental components of life. But in fact, it was in 1866 that Mendel first recorded the results of growing pea plants. He understood that both the parent plants had influenced the genetic make-up of the new plant.
 
In 1973, biochemists Cohen and Boyer discovered a procedure to use enzymes — chemicals formed in the body — to unzip the DNA, to cut out a sequence of genes, and finally to insert them into the host cell and combine with its DNA.
 
Cloning takes the DNA from a single cell to create a whole new individual. A clone is an organism which is genetically identical to another one. But it's now certain that no clone is an exact copy because of differences in experiences and upbringing.
 
There are at least two teams of scientists which are trying to clone humans. Although controversial, there are many valid reasons to do so. An Italian doctor wants to offer cloning as an optional treatment for couples who find it difficult to have children. But anyone who was a clone of one of their parents would be under unknown psychological pressure throughout their childhood.
 
Another reason is to reproduce the talents of exceptional human beings. But an Einstein clone might choose a path in life which is contradictory to the one the original Einstein chose. He may even possess new vices instead of existing virtues!
 
A further reason is to obtain a supply of stem cells. Stem cells in embryos are very flexible and can develop into every other type of cell in the body. For example, it could help someone recover from a disease, repair human tissue, or help them walk again after an accident. These stem cells would need to come from an embryo taken from the clone of someone. But the embryo would then be wasted, which many people find unacceptable. What is clear is that some voluntary code of practice among scientists has to be agreed. If not, compulsory government regulations will have to control cloning.
 
A fourth reason for cloning is that some scientists and farmers think it would be handy to clone, for example, a prize cow which can resist bacteria or disease, or to sow a cloned crop which can resist rot or pests. But to rely on a few cloned animals or crops would restrict the biodiversity of the breed.
 
Finally, the latest research into DNA has helped solve crimes by analysing the suspect's saliva which they spit at a crime scene or the dirt under their fingernails.