TOPIC 3: CLASSIFICATION Flashcards
What are the stages of classification system according to the hierarchy? (Include an example)
- Domain (Eukaryota)
- Kingdom (Animalia)
- Phylum/division (Chordata)
- Class (Mammalia)
- Order (Primates)
- Family (Hominidae)
- Genus (Homo)
- Species (Sapiens)
What does the binomial name tell you about the organism?
First part of the binomial name tells us the genus, the second part tells us the species.
Define species.
A group of living organisms with similar characteristics which interbreed to produce fertile offspring.
Ecological species model
Based on the ecological niche occupied by an organism.
Limitations: Niche definitions vary and many species occupy more than one niche
Mate-recognition species model
Based on unique fertilisation systems, including mating behaviour
Limitations;
Many species will mate or cross-pollinate and produce fertile hybrids but be of the same species
Genetic species model
Based on DNA evidence
Limitation: Some people find it hard to decide how much genetic difference makes two organisms members of different species.
Evolutionary species model
Based on shared evolutionary relationships between species/organisms.
Limitations: Sometimes there is not always a clear evolutionary pathway for a particular organism
What are the limitations of the species model?
- Finding evidence – many living species have never been observed mating.
- Plants of different but close species frequently interbreed and produce fertile hybrids
- Many organisms do not breed sexually but asexually so definition involving reproductive behaviour is irrelevant
- Sexual dimorphism – There is a great deal of variation between males and females of the same species
Distinguish between analogous characteristics and homologous characteristics.
Analagous characteristics have a similar structures but different evolutionary origins.
Homologous characteristics are structures of a similar origin but different functions
Outline allopatric and sympatric speciation.
Allopatric speciation is caused by geographical separation whereas sympatric speciation occurs within the same habitat caused by different niches (behavioral/courtship/feeding differences)
Both processes lead to the isolation of sub populations
Define Speciation
Speciation is the formation of a new species by the splitting /separation of an existing species
How can gel electrophoresis be used to distinguish between species and determine evolutionary relationships?
DNA AND RNA SEQUENCING
- DNA sample + restriction enzymes
- DNA is cut into fragments
- DNA fragments loaded into wells in agar gel
- DNA molecules negatively charged
- DNA molecules move when potential difference
- Lighter molecules move further up gel
- Compare sample from organisms – more closely related organisms will have similar band patterns
List the ways in which scientists check validity of investigations
- Scientific journals
- Peer review
- Conferences
Describe the differences between the 5 kingdoms
- Prokaryotae – Bacteria and cyanobacteria, unicellular, reproduce asexually.
- Protoctista – Eukaryotes, mostly unicellular, mainly reproduce sexually.
- Fungi – Eukaryotes, mainly multicellular, non-motile, heterotrophic nutrition, sexual and asexual reproduction.
- Plantae – Eukaryotes, multicellular, non-motile, autotrophic nutrition, sexual and asexual reproduction.
- Animalia – Eukaryotes, multicellular, motile heterotrophic nutrition, mainly sexual reproduction but some reproduce asexually.
Describe the differences between the 3 domains.
See image