Mark scheme - Unit F225 - Genetics, control and ageing ... - OCR

F225 Mark Scheme January 2013
Question Answer Mark Guidance
(iii) autosomal
3
not a sex chromosome ;
CREDIT reference to chromosome 9 being an autosome
AND ANY TWO FROM
linkage
loci F and G close together (on chromosome) ;
less chance of a ,
cross over event / chiasma formation, between them ;
ACCEPT reference to genes or
to genes for ABO and nail patella syndrome.
CREDIT reverse argument - both exchanged together during
cross over event
(so more likely to be) inherited together ;
2