K.C.S.E Biology Q & A - MODEL 2004PP1QN14
What is meant by the following terms? Give an example in each case.
i) Homologous structures
iii) Vestigial structures Example
(i) Have a common ( embryonic) origin modified to perform different functions; vertebrae for limb/ pentadactyl limb
Vertebrate fore limb/ pretadactyl limb; acc beaks of birds ( fee of birds/ mouthparts in insects.
(ii) Have different (embryonic) origins ( but have evolved) to perform similar functions.
(iii) Are greatly reduced in size and therefore caused to function
Acc. Third digit of wing of bird
Halteres in flies
Presence of hind limb ( buds) in python
Human ear muscles
Human appendix / kiwi ( flightless bird) with reduced wings/ vestigial wings in flies human hair/ presence of hind limbs in python; reduced pelvic girdle of whale.