RELATEDNESS OF ORGANISMS Flashcards
1
Q
homologous structures
A
- different function/shape, similar origin
2
Q
example of homologous structure (4)
A
- pentadactyl limb
- same structure in all terrestrial vertebrates
- but different uses, i.e flight (birds), swimming (whale fin), grasping (hands)
- also divergent evolution
3
Q
divergent evolution
A
- common structure evolved for different functions
4
Q
analogous structures
A
- same function/shape, different origin
5
Q
convergent evolution
A
- adapted to the same environment so developed similar structure
6
Q
assessing relatedness (4)
A
- DNA sequencing - similarities in DNA base sequences has confirmed evolutionary relationships and corrected mistakes in classification based on physical structures
- DNA hybridisation - compare base sequences of two species by extracting, separating & cutting into fragments, then mixing and shared sequences hybridise
- Amino acid sequences - reflect how closely related they are, comparing fibrinogen molecule
- Immunology - proteins of different species are mixed
7
Q
steps of immunology (4)
A
- inject A serum into B
- collect B serum with A antibodies
- add B serum with A antibodies to serum of other species
- precipitate forms depending how closely related A is to the other species
8
Q
two definitions of species
A
- morphological - two similar-looking organisms are likely to be related, with sexual dimorphism taken into account
- reproductive definition - two organisms can interbreed to produce fertile offspring
9
Q
sexual dimorphism
A
- when males and females of a species look slightly different
10
Q
taxonomy allows us to…?
A
- discover and describe biological diversity
- investigate evolutionary relationships between organisms
- classify organism to reflect evolutionary relationships
11
Q
binomial name
A
Genus species (italics)
12
Q
advantages of binomial system (3)
A
- unambiguous
- based on latin so can be used everywhere
- implies relatedness based on genus
