8/10/2019 BIO Extended Response Final Exam 2007

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8/10/2019 BIO Extended Response Final Exam 2007

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23 $ead te first "rocess if more tan one is gi%en393 :i"osomes ; u" to 4 marks3

!rocess of protein synthesis in bacterial cells: maximum 6 marks

8/10/2019 BIO Extended Response Final Exam 2007

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BIOLOGY MARKING SCHEME 2007 , EXTENDED RESPONSE

Version 2 No$e%&er '(

)es*ion (-

There is strong evidence for the common ancestry of all living things. "iologists believe that the evolution of eu#aryotic

cells from pro#aryotic cells probably involved endosymbiotic events.

$%plain how the study of DNA provides strong evidence for the common ancestry of all living things.

Describe the differences in the internal structure of pro#aryotic and eu#aryotic cells.

Describe the process of endosymbiosis and provide onepiece of evidence of the evolution of eu#aryotic cells by

endosymbiosis.

&tudy of DNA: maximum 4 marks (2 for eac "oint)

DNA is "resent in all li%ing organism 1

DNA contains te same nitrogenous bases in all li%ing tings 1

enetic code is te same for all li%ing tings 1

@ame m$NA codes for same amino acid $ same 9 bases used to code for an amino acid 1

@ame t$NA carries te same amino acid 1

+rocess of "rotein syntesis is te same 1

All li%ing tings use te same 27 amino acids ; based on same code 1 DNA BDNA ybrdisation sows base seuence in many organisms is similar (1) indicating common ancestor (1) 2

@imilar "roteins (1) (eg cytocrome c) reflects common base seuence (1) 2

DNA seuencing can sow similarity between s"ecies 1

All li%ing tings can transcribe oters DNA/genes can be transferred between s"ecies C still work 1

Note> @tudents sould state tat all of tese features indicate common ancestry3

Describe differences in internal structure of pro#aryotes and eu#aryotes: maximum 4 marks (2 for eac "oint)

+s a%e little internal organisation& s a%e ig le%el of internal organisation 2

+s a%e no nucleus (or a%e a nucleosome)& s a%e a nucleus 2

+s a%e no membrane bound organelles& s a%e membrane bound organelles 2

+s a%e a single cromosome& s a%e 2 or more cromosomes 2

+s a%e "lasmids& s do not3 2

+s DNA is circular& s is linear 2

+s ribosomes are small (E7@)& s are larger (F7@) 2

+s a%e less cytoskeleton tan s3 2

+s a%e no s"indle and s do3 2

+s DNA does not a%e istones and introns& s do3 2

Note>13 @tudents sould describe bot "rokaryotes and eukaryotes to" get te full 2 marks for 1 feature3

23 A list of features wit no descri"tions ; max 293 ,f we use com"arati%e terms (eg smaller& more) ten allow te 2 marks3

!rocess of endosymbiosis and one piece of evidence> maximum 4 marks (2 "oints)

+rokaryotic cells existed before eukaryotic cells 1

:arger "rokaryotic cells (1) engulfed (1) smaller "rokaryotic cells 2

laboration of engulfing (eg "agocytosis) 1

ngulfed cells carried on functioning (1) so te new cell/combination could carry out more functions (1) 2

xam"leGG .lams wit cyanobacteria 2

.loro"lasts C mitocondria a%e teir own DNA (1) se"arate from te nucleus (1) 2

.loro"last C mitocondrial DNA is circular $ resembles "rokaryotic DNA 1

.loro"lasts C mitocondria a%e teir own ribosomes (1) wic resembles bacterial ribosomes (1) 2

.loro"lasts C mitocondria are able to selfBre"licate (1) inde"endently of te cell (1) 2

.loro"lasts C mitocondria re"lication resembles binary fission of "rokaryotes 1 .loro"lasts C mitocondria a%e 2 membranes (1)H outer is similar to ost cells& inner resembles bacterial(1) 2

.s and s syntesis teir own "roteins 1

Note>13 Iot sections must be answered ere for 4 marks3/%ar/www/a""s/con%ersion/tm"/scratc51/271481163doc