Стр.158-159 Unit 11-12 ГДЗ Комарова Ларионова 11 класс
Learn about science A Work with a partner. Can you think of how science helps the police solve crimes? These key words might help you.
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Приведем выдержку из задания из учебника Комарова, Ларионова 11 класс, Русское слово:
Learn about science
A Work with a partner. Can you think of how science helps the police solve crimes? These key words might help you.
blood
hair
DNA
soil samples
fingerprints
teeth
gunpowder
B Can you answer these questions?
a Why would a criminal wear gloves to commit a crime?
b Apart from the face, how can you find out who somebody is?
c What other unique features do our bodies have?
d Is it possible to tell when people are lying?
C Now read the text and decide whether your answers were correct.
The unique finger
Forensic scientists can identify criminals and their victims in many different ways now, but the fingerprint is still the most effective means of identification. A fingerprint is unique. Each individual has a slightly different pattern on the tips of the fingers, and even if the skin is removed, when it grows back the same pattern reforms. There are tiny sweat glands in the fingertips and when we touch different surfaces, an imprint is left behind.
Fingerprints are not always visible to the naked eye, but at a crime scene, police have a number of methods for finding prints and inputting them into computer systems. Most commonly, a black powder such as ninhydrin is brushed over an area. The powder sticks to the oil from the fingerprints and the print becomes visible. The prints can then be photographed or collected using tape. If a print is on a substance like paper which is porous, the police can use iodine to make the print show up, then, photograph it. Prints will also show up under the light from an argon laser. Surfaces can be dusted with fluorescent powder for this to work. Police rarely uncover a complete fingerprint, yet computer systems can find a match to even a small part of a print. Ninety-two per cent of fingerprint matches in the US arc completed using the computer system with no human intervention.
Now researchers are looking at ways to lift fingerprints from cloth. They are trying to use a metal vapour which rests on top of the fingerprints. This doesntaskt yet allow police to make a fingerprint match, but it would be a way to discover whether or not a person has really been the victim of an attack.
My DNA or your DNA
DNA fingerprinting is relatively new. Examples of our DNA can be found everywhere because it is in our cells. So, there is DNA in our hair, in our saliva, on our skin and in our blood. The chemicals in DNA are always the same, but everybodytasks DNA is linked up in a slightly different pattern so our DNA, or genetic makeup, is more or less unique.
DNA fingerprinting is a way to identify criminals, but it is difficult. To analyze DNA, you need to get the DNA out of the hair, skin, saliva or blood sample. This is a complex chemical procedure and errors are always possible. However, if a DNA pattern is identified successfully, it is a very effective method of finding dangerous criminals. As with fingerprints, there are databases of the DNA profiles of dangerous criminals and the police can use these systems to find a match.
Usually, however, to identify the criminal, police will need to match two DNA samples. The police may need special permission to take a DNA sample from a suspect.
Other clues
There are other ways to identify criminals or victims. There are other unique patterns in the human body and without realizing, we carry clues which show what we have been doing or where we have been.
A soil sample carried on the soles of our shoes can be evidence of having been present at the scene of a crime. A victim can be identified using dental records, or a criminal could be found using the imprint of lips on the side of a glass. If a crime has been committed, it is likely that something will point the police in the right direction.
Even though not scientifically proven, body language can tell us whether or not a suspect is lying. When lying, people tend not to look you in the eye, they are not as relaxed and their body movements are more strained.
Science may make crimes easier to solve, but it doesntaskt mean there are less of them.
D Answer the questions.
1 What are the three methods that police use for identifying fingerprints?
2 How do police match up fingerprints?
3 Why is fingerprinting and DNA fingerprinting a way to identify criminals?
4 Why do you think there is controversy about DNA profiling and fingerprinting? Think about the fact that once you have given a DNA sample, police might keep it even if you haventaskt committed a crime.
Unfired state exam
Steps to success
In Speaking Task I when you read the text aloud, dontaskt go too fast or too slow. Try to read it naturally. Pause slightly at each comma and full stop.
E Choose a paragraph from the text and read it aloud.
Imagine that you are preparing a project with your friend. You have found some interesting material for the presentation and want to read it to your friend. You have 1.5 minutes to read the text silently, then be ready to read it aloud. You will not have more than 1.5 minutes to read it.
Project: Finding clues
Read the description of a crime scene below. Imagine you are a police detective. What could you do to get clues? Use the information in the texts to help you.
At the crime scene we observed the following:
The door had been opened from the inside, but a window near the door had been broken. There were tiny drops of blood near the window. A glass with lipstick on it was left on the table. There was a mark from a high heel and a dirty stain on the floor. Somebody had tried to open a safe. There was a long strand of hair near the safe.