Infection, Immunity & Forensics - EXAM QUESTIONS Flashcards
FORENSICS
Explain the role of DNA primers in the production of the [amplified 345bp sequennce]
[2 Marks]
- Primers have a specific base sequence
- bind to complemetary bases of the DNA to be amplified
- therefore, provides a site for the DNA polymerase to bind
FORENSICS
Explain why the amplified DNA fragments for 2 alleles in a population are different.
[3 Marks]
- The base sequence of the alleles are different
- The restriction enzyme cuts at a specific DNA base sequence
- That is only present in the [specific - G202110A] enzyme.
FORENSICS
Devise an investigation to determine the optimum number of cycles for the polymerase chain reaction used to amplify the DNA for this test.
[4 Marks]
Use gel electrophoresis to determine the quantity of DNA produced.
- Change the number of cycles
- Mononucleotides should be provided in excess
- Control Temperatures - at 95, 55 and 70 degrees celcius
Choose the smallest number of cycles that produces an observable band
FORENSICS
Comment on the effect of adding cow dung to composting coffee husks.
[3 Marks]
***Specific table question
- Adding cow dung does not change the decrease in organic carbon
- Adding cow dung causes a slight change to the increase in nitrogen
- Adding cow dung has no significant effect on the composting of coffee husks
FORENSICS
Body farms use the bodies of pigs to study the changes in insect species on a body after death.
Describe how this study could be carried out
[3 Marks]
- Same size/ age/ breed of pig
- Controlled abiotic factor such as temperature
- Record the presence of different species … at regular intervals of time for example - hourly.
FORENSICS
Explain how the results of this study could be used to help to establish the time of death of a human.
[3 Marks]
- Record which insects are present on the human
- Compare with results from investigation on pigs to determine time of death
- Take into account which stages of the lifecycle are present
FORENSICS
Describe how DNA profiling could be carried out to show that these snakes are different species.
[4 Marks ]
- DNA obtained from the two types of grass snake
- Restriction Enzymes used to produce fragments of DNA
- Gel electrophoresis used to analyse the DNA samples
- Gel electrophoresis used to seperate the fragments of DNA -
more differences in the pattern of bands produced would indicate that the snake are different species.
FORENSICS
Describe the changes that occur inside a body in the first week after death.
[3 Marks]
- Body temperature falls
- Rigor Mortis Occurs
- Autolysis occurs - followed by discoloration and bloating
FORENSICS
Describe the role of decomposers, such as microorganisms, in the carbon cycle.
[ 2 Marks ]
- Decomposers break down organic material from the dead body
- Decomposers respire and release carbon dioxide into the atmosphere
FORENSICS
Explain the effect of temperature on the rate of growth of blowfly maggots.
[ 3 Marks]
- Temperature affects enzymes
- an increase in temperature increases kinetic energy
- producing more frequent collisions between enzyme and substrate molecules
FORENSICS
Describe a procedure, using electrophoresis, to compare the amplified DNA from these two types of humans.
[4 Marks]
- Restriction enzymes used to cut DNA into fragments.
- DNA samples are loaded onto agarose gel.
- Electrical current is passed through the gel.
- Markers are added to visualise the bands.
- The position of the bands produced can be compared.
FORENSICS
A deer was found dead on national trust land.
The DNA produced by PCR was analysed to find out if a black panther was involved.
Explain how gel electrophoresis could be used to find out if this DNA came from black panther.
[5 Marks ]
- Use of agarose gel to be loaded in the electrophoresis tank
- A current is applied across the gel
- Use of a DNA strain such as Flurosecent dye
- Use of DNA of the black panther
- Compare DNA profiles - a match would indicate that DNA from a black panther was present.
FORENSICS
Explain the effects of ambient temperature on the rate of decomposition.
[3 Marks]
- An increase in temperature will increase the rate of decomposition.
- This increases enzyme activities.
- An increase in temperature increases growth rate of Bacteria.
FORENSICS
What is Phosphate in plants used to synthesise
[1 Mark]
Polynucleotides and Phospholipids
FORENSICS
Explain how microorganisms in the soil break down the stems
[3 Marks]
- The stems contain starch or cellulose
- Enzymes are released by the microorganisms … which breaks down the glycosidic bonds
- Releases glucose that is used in microorganisms in respiration.
