Methods for typing blood were developed around the turn of the century

Question

Methods for typing blood were developed around the turn of the century, about the same time that fingerprints were first used for identification. Only in the last decade or two, however, have scientists begun to believe that genetic markers in blood and other bodily fluids may someday prove as useful in crime detection as fingerprints.

The standard ABO blood typing has long been used as a form of negative identification. Added sophistication came with the discovery of additional subgroups of genetic markers in blood and with the discovery that genetic markers are present not only in blood but also in other bodily fluids, such as perspiration and saliva.

These discoveries were of little use in crime detection, however, because of the circumstances in which police scientists must work. Rather than a plentiful sample of blood freshly drawn from a patient, the crime laboratory is likely to receive only a tiny fleck of dried blood of unknown age from an unknown  “donor”  on a shirt or a scrap of rag that has spent hours or days exposed to air, high temperature, and other contaminants.

British scientists found a method for identifying genetic markers more precisely in small samples. In this process, called electrophoresis, a sample is placed on a tray containing a gel through which an electrical current is then passed. A trained analyst reads the resulting patterns in the gel to determine the presence of various chemical markers.

Electrophoresis made it possible to identify several thousand subgroups of blood types rather than the twelve known before. However, the equipment and special training required were expensive. In addition, the process could lead to the destruction of evidence. For example, repeated tests of a blood-flecked shirt - one for each marker - led to increasing deterioration of the evidence and the cost of a week or more of laboratory time.

It remained for another British researcher, Brian Wrexall, to demonstrate that simultaneous analyses, using an inexpensive electrophoresis apparatus, could test for ten different genetic markers within a 24-hour period. This development made the study of blood and other fluid samples an even more valuable tool for crime detection.   1 
 1. The author of the passage is primarily concerned with describing

A. How advances in crime detection methods have led to new discoveries in science
B. Various ways in which crime detection laboratories assist the police
C. The development of new scientific tools for use in crime detection
D. Areas of current research in the science of crime detection
E. Developments in genetic research and their application to crime detection

2 
 2. It can be inferred from the passage that electrophoresis resembles fingerprinting in that both

A. Provide a form of negative identification in crime detection
B. Were first developed by British scientists
C. May be used to help identify those who were present at the time of a crime
D. Were developed by scientists at around the same time
E. Must be employed almost immediately after a crime to be effective

3 
 3. The author sets off the word “‘donor’” ( Highlighted ) with quotation marks in order to

A. Emphasize that most of the blood samples received by crime laboratories come from anonymous sources
B. Underscore the contrast between the work done in a crime laboratory and that done in a blood bank
C. Call attention to the fact that, because of underfunding, crime laboratories are forced to rely on charitable contributions
D. Show that the word is being used in a technical, rather than a general, sense
E. Indicate that the blood samples received by crime laboratories are not given freely

4 
 4. The passage contains information that would answer which of the following questions?

A. Is evidence of genetic markers in bodily fluids admissible in court?
B. Can electrophoresis be used to identify genetic markers in saliva?
C. How many subgroups of blood types are currently identifiable?
D. How accurate is the process of electrophoresis?
E. How many tests for genetic markers must police scientists run in order to establish the identity of a criminal?

5 
 5. According to the passage, all of the following may reduce the usefulness of a fluid sample for crime detection EXCEPT

A. The passage of time
B. Discoloration or staining
C. Exposure to heat
D. The small size of the sample
E. Exposure to contaminants

6 
 6. The passage implies that electrophoresis may help scientists determine

A. Whether or not a sample of blood could have come from a particular person
B. The age and condition of a dried specimen of blood or other bodily fluid
C. When and where a crime was probably committed
D. The cause of death in homicide cases
E. The age, gender, and ethnic background of an unknown criminal suspect

7 
 7. According to the passage, Brian Wrexall’s refinement of electrophoresis led to

A. More accurate test results
B. Easier availability of fluid samples
C. Wider applicability of genetic analysis
D. Increased costs of testing
E. More rapid testing

8 
 8. Which of the following statements about genetic markers can be inferred from the passage?

I. They carry an electrical charge.
II. They cannot be identified through standard ABO blood typing.
III. They were of no use in crime detection before the invention of electrophoresis.

A. I only
B. II only
C. III only
D. II and III only
E. I, II, and III

mimishyu · Answer

para1
the prelude—methods for typing blood and how its potential genetic marker in blood and other bodily fluids in recent days

para2
follow para1 by giving more detail information about the discovery of genetic markers within the standard ABO blood typing

para3
the limitation to those genetic markers used in crime detection since we had to consider the external environmental factors

para4
way out to the difficulties ran into those genetic markers method by introducing another method-- electrophoresis and further express it in detail

para5
keep saying on how the electrophoresis method work

para6
the author sum an end to the whole passage by recommend the potential to this new method

1. The author of the passage is primarily concerned with describing

A. How advances in crime detection methods have led to new discoveries in science

the discoveries in this passage is genetic markers which doesn’t be new, the old method already talk about this

B. Various ways in which crime detection laboratories assist the police

this statement totally out of scope

C. The development of new scientific tools for use in crime detection

....correct

The former part of the passage states the limitation to an old method-- the standard ABO blood typing and then introduce a new method—electrophoresis in the latter part for solving the problem to the old one, so the development of new scientific tools is the main point in this passage

D. Areas of current research in the science of crime detection

the passage not only concern “current” research, it also address the method in the old time,

E. Developments in genetic research and their application to crime detection

the crux in this option, as I thought, is that its too narrow of scope if we deem the methods in the passage as “research”, the same problem was also in option(D)

2. It can be inferred from the passage that electrophoresis resembles fingerprinting in that both

A. Provide a form of negative identification in crime detection

see the first sentence in para2
The standard ABO blood typing has long been used as a form of negative identification.
we only know the method prior to the electrophoresis provide a form of negative identification, to this point we had no trace to judge whether electrophoresis and fingerprinting has something to do with this form of negative identification

B. Were first developed by British scientists

only sentence in para4 say about “British scientists”
British scientists found a method for identifying genetic markers more precisely in small samples. In this process, called electrophoresis,........
we cannot simply from this point to conclude that electrophoresis resembles fingerprinting in that both were first developed by British scientists

C. May be used to help identify those who were present at the time of a crime

......correct

from the last sentence of para1:
Only in the last decade or two, however, have scientists begun to believe that genetic markers in blood and other bodily fluids may someday prove as useful in crime detection as fingerprints.

to the first sentence in para3&4
These discoveries were of little use in crime detection,..........

British scientists found a method for identifying genetic markers more precisely in small samples. In this process, called electrophoresis,.......

from above, if not considering their relative effectiveness, we could say that those sentences to fingerprinting as well as electrophoresis are indeed both used at a crime scene

D. Were developed by scientists at around the same time

the first sentence in para1
(old) methods for typing blood were developed around the turn of the century, about the same time that fingerprints were first used for identification.
but as we know these methods for typing blood doesn’t effective so that a new method- electrophoresis- was proposed, we could see very clearly here it present the order in that fingerprinting must show up prior to electrophoresis

E. Must be employed almost immediately after a crime to be effective

must be employed almost immediately....nowhere in the passage mention about this

3. The author sets off the word “‘donor’” (Highlighted) with quotation marks in order to

A. Emphasize that most of the blood samples received by crime laboratories come from anonymous sources
B. Underscore the contrast between the work done in a crime laboratory and that done in a blood bank
C. Call attention to the fact that, because of underfunding, crime laboratories are forced to rely on charitable contributions
D. Show that the word is being used in a technical, rather than a general, sense
E. Indicate that the blood samples received by crime laboratories are not given freely

I choose (A) at first but found (E) correct, I just guess the reason why (E) be the correct choice is that, maybe, it consider the whole text in that crime laboratories can only receive a small amount of sample rather than only consider the meaning of this word “donor”, but I’m not really for sure

4. The passage contains information that would answer which of the following questions?

A. Is evidence of genetic markers in bodily fluids admissible in court?

see the statement in para2&3
....discovery of additional subgroups of genetic markers in blood and with the discovery that genetic markers are present not only in blood but also in other bodily fluids, such as perspiration and saliva.

These discoveries were of little use in crime detection,.....

we could only infer from the passage that, before electrophoresis introduce, genetic markers are of little use in crime detection, but nowhere in the passage could we trace whether or not it is allowable in court

B. Can electrophoresis be used to identify genetic markers in saliva?

......correct
see para4
British scientists found a method for identifying genetic markers more precisely in small samples. In this process, called electrophoresis, a sample is placed on a tray containing a gel through which an electrical current is then passed. A trained analyst reads the resulting patterns in the gel to determine the presence of various chemical markers(

accordingly above, and as we know from para2 these markers including saliva, thus we could infer that electrophoresis can be used to identify genetic markers in saliva).

C. How many subgroups of blood types are currently identifiable?

we can only know from sentence in para2 that beside the standard ABO blood typing there also exist “additional subgroups” of genetic markers, but the para doesn’t give us the definite number as to how
many subgroups of blood types are currently identifiable

D. How accurate is the process of electrophoresis?

the first sentence in para4 “British scientists found a method for identifying genetic markers more precisely in small samples.”, we only know the method of electrophoresis is more precise, but nowhere in the passage ever talk about its accurate level

E. How many tests for genetic markers must police scientists run in order to establish the identity of a criminal?

same as (D),nowhere in the passage mention about the quantity as for how many tests for genetic markers must police scientists run

5. According to the passage, all of the following may reduce the usefulness of a fluid sample for crime detection EXCEPT

see para3 
Rather than a plentiful sample of blood freshly drawn from a patient, the crime laboratory is likely to receive only a tiny fleck of dried blood of unknown age from an unknown “donor” on a shirt or a scrap of rag that has spent hours or days exposed to air, high temperature, and other contaminants.

A. The passage of time
see words in the last sentence...
has spent hours or days exposed to

B. Discoloration or staining
...correct
nowhere in the passage mention this

C. Exposure to heat

high temperature

D. The small size of the sample
see sentence....
Rather than a plentiful sample of blood freshly drawn from a patient..............
so this be factor that will reduce the usefulness of a fluid sample

E. Exposure to contaminants
.... and other contaminants

6. The passage implies that electrophoresis may help scientists determine

A. Whether or not a sample of blood could have come from a particular person

para4
British scientists found a method for identifying genetic markers more precisely in small samples. In this process, called electrophoresis, a sample is placed on a tray containing a gel through which an electrical current is then passed. A trained analyst reads the resulting patterns in the gel to determine the presence of various chemical markers.
also, see para1
Only in the last decade or two, however, have scientists begun to believe that genetic markers in blood and other bodily fluids may someday prove as useful in crime detection as fingerprints.

connect para1 to para4
genetic marker come available in electrophoresis process, thus at least for now, it is proven useful in crime detection as fingerprints and by this we are able to determine whether the sample of blood
come from a particular person

B. The age and condition of a dried specimen of blood or other bodily fluid

Age of a dried specimen
.... well, the word “age” never ever show up in the passage

C. When and where a crime was probably committed

here we’re not concern with the time and space to which a crime happened

D. The cause of death in homicide cases
E. The age, gender, and ethnic background of an unknown criminal suspect

indeed “crime detection as fingerprints” is a main point the passage care about here, but the passage not mention anything that it care about “the age, gender, and ethnic background” of the suspect

C D E are totally out of scope

7. According to the passage, Brian Wrexall’s refinement of electrophoresis led to

last paragraph
It remained for another British researcher, Brian Wrexall, to demonstrate that simultaneous analyses, using an inexpensive electrophoresis apparatus, could test for ten different genetic markers within a 24-hour period. This development made the study of blood and other fluid samples an even more valuable tool for crime detection.

A. More accurate test results
nowhere in the last paragraph mention about this

B. Easier availability of fluid samples
“easier availability” means “we could attain these samples more easily”but the wording in this option doesn’t necessary mean “valuable”

see fluid sample in para2
that genetic markers are present not only in blood but also in other bodily fluids, such as perspiration and saliva.

and last para 
This development made the study of blood and other fluid samples an even more “valuable” tool for crime detection.

C. Wider applicability of genetic analysis
D. Increased costs of testing
E. More rapid testing
...correct, see sentence “could test for ten different genetic markers within a 24-hour period”

8. Which of the following statements about genetic markers can be inferred from the passage?

I. They carry an electrical charge.

British scientists found a method for identifying genetic markers more precisely in small samples. In this process, called electrophoresis, a sample is placed on a tray containing a gel through which an electrical current is then passed. A trained analyst reads the resulting patterns in the gel to determine the presence of various chemical markers.

II. They cannot be identified through standard ABO blood typing.

From para2, we know they indeed can be identified through ABO blood typing

The standard ABO blood typing has long been used as a form of negative identification.
Added sophistication came with the discovery of additional subgroups of genetic markers in blood and with the discovery that genetic markers are present not only in blood but also in other bodily fluids, such as perspiration and saliva.

III. They were “of no use” in crime detection before the invention of electrophoresis.

para3
These discoveries were “of little use” in crime detection, however, because of the circumstances in which police scientists must work. Rather than a plentiful sample of blood freshly drawn from a patient,

“of no use” doesn’t equal to “of little use”, the word “no” means “none of anyone” while we could still have something left for this wording “little”

A. I only ....correct
B. II only
C. III only
D. II and III only
E. I, II, and III

ottocento · Answer

The purpose of the quotation marks is to indicate that the word "donor" is not to be taken literally. Generally a blood donor is a person who gives blood voluntarily. The source of traces of blood found at a crime scene cannot be described as a person who has given blood voluntarily. The answer is (E).

(A) does not express the purpose of the quotation marks. The word "unknown" makes it explicit that the source is anonymous, but the quotation marks around the word "donor" do nothing to emphasize that anonymity.

MPRS22 · Answer

Any explanation for question 1? I marked E and don't understand why it is C

VeritasKarishma

KarishmaB · Answer

Look at the way the passage is structured:

"Methods for typing blood were developed around the turn of the century, about the same time that fingerprints were first used for identification."...
"The standard ABO blood typing has long been used as a form of negative identification."...
"British scientists found a method for identifying genetic markers more precisely in small samples."...

It describes the development of tools for use in crime detection. It describes research done to make crime detection easier.

The passage does not focus on general genetic research and its application to crime detection. The passage focusses on things that were developed to make crime detection easier.

Hence (C) is better.

VerbalBot · Answer

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Methods for typing blood were developed around the turn of the century

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