Biology Unit 4: Edexcel Ial Ppqs Qustions With Complete Solutions
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Module
Biology: Edexcel
Institution
Biology: Edexcel
Biology Unit 4: Edexcel Ial Ppqs Qustions
With Complete Solutions
Explain how the increases in CO2 and CH4 released into the atmosphere may be contributing
towards the estimated changes mean temperature. 1) CO2 and CH4 are both greenhouse
gases.
2) trap/absorb heat/IR/long-wave radiation /e...
Explain what is meant by gene mutation 1) change in DNA
2) ref. to change/deletion/addition/duplication/substitution/eq. of bases/nucleotides.
,Biology Unit 4: Edexcel Ial Ppqs Qustions
With Complete Solutions
Theory used in DNA profiling 1) DNA profiling assumes everyones DNA is
unique/different/eq.
2) apart from identical twins/eq.
3) ref. to DNA profiling analyses the introns/nc-blocks/short tandem repeats/eq.
4) nc-DNA is very variable/eq.
5) large number of introns/nc-blocks/eq.
6) idea of many combinations/eq. at each locus.
Explain why evidence from DNA profiles may not be absolutely conclusive. 1) ref. to
DNA profiling has several stages.
2) ref. to contamination/eq. can arise at any stage.
3) only a few sequences/small portion of DNA is analyses/eq.
4) ref. to possibility of 2 identical profiles form unrelated individuals.
5) identical twins/closely related individuals/eq. may show same profile/eq.
Suggest hoe DNA profiling could be useful to scientists who examine fossils of animals and
plants 1) comparisons made between DNA from fossils and other organisms.
, Biology Unit 4: Edexcel Ial Ppqs Qustions
With Complete Solutions
2) to find genetic relationships/eq.
3) ref. to use in taxonomy/ classification/eq.
4) to understand evolutionary lines/ to determine common ancestors/eq.
State how the genetic material in HIV differs from the genetic material in the
bacterium Mycobacterium tuberculosis that causes TB. 1) RNA in HIV and DNA in
M.TB/eq.
2) comparative description of nucleic acid (e.g circular in M.TB and linear in HIV).
3) plasmids in M.TB and no plasmids in HIV.
Explain why unbroken skin is an effective barrier against HIV infection 1) keratin in skin
surface/epidermis.
2) idea of forms a hard/ impenetrable/ physical/ eq. barrier.
Explain the decrease in numbers of CD4 T-lymphocytes during the first 6 weeks after infection
with HIV. 1) glycoprotein on virus/ eq.
2) binds with receptors/CD4/eq.
3) on membrane of lymphocytes/ eq.
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