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AS Classification
AS Biology Chapter 10
Question | Answer |
---|---|
In classification- what are the 7 taxonomic groups in the system most widely used until recently? (in order of hierarchy). AKA Linnaean system. | Kingdom, Phylum, Class, Order, Family,Genus, Species. |
What is the newest level of classification to be added to the system? | DOMAIN (3 domain system). |
What is classification? | Sorting living organisms into groups that share similar features |
Why do we classify organisms? | 1. To identify species. 2. To predict characteristics. 3. To find evolutionary links. |
What are the advantages and disadvantages of using a single worldwide classification system? | Scientists all over the world can share research. Links between different organisms can be seen, even if they live a long way apart. Disadvantage is that system has been created by us to observe organisms- it is not defined by nature. |
What are the 3 domains? | Eukarya: Archaea; Bacteria |
What happens to the characteristics of organisms in a group as you go down the hierarchy? | There are fewer types of organisms and they share more of the same characteristics (ie.e become more similar). |
What is a species? | A group of organisms that are able to reproduce FERTILE offspring. |
How do we know that donkeys and horses are separate species. Why are mules and hinnies infertile? | Because they produce infertile animals -mules or hinnies. These contain an odd number of chromosomes which means that meiosis and gamete production cannot take place correctly.. |
Classify a human. | Domain-Eukarya; Kingdom- Animalia; Phylum-Chordata; Class- Mammalia; Order-primates; Family- Hominidae; Genus- Homo; Species-Sapiens. |
What is binomial nomenclature (Linnaean system). | All species are given a name consisting of 2 parts - Genus and Species. It ensures scientists all over the world are naming and discussing the same organism. |
What are the 5 Kingdoms? | Prokaryotae (bacteria); Protoctista (unicellular eukaryotes); Fungi (yeasts and moulds); Platae (plants); Animalia (animals). |
General Features of Prokaryotae | Unicellular; DNA ring NOT contained in a nucleus; no other membrane bound organelles; small ribosomes; no visible feeding mechanisms. |
General features of Protoctista | Mainly unicellular; Nucleus and other membrane bound organelles; some can move; nutrients may be gained through photosynthesis (Autotrophs) or ingestion of other organisms (Heterotrophs). Some are parasitic. |
General Features of Fungi | Uni or multicellular; nucleus and other membrane bound organelles; cell wall made of chitin. No chloroplasts, no movement. Nutrients are acquired by absorption, usually of decaying material- Saprophytic feeders. e.g. mushrooms |
General features of plantae | Multicellular; nucleus and other membrane bound organelles; cell wall made of cellulose; contain CHLOROPHYLL; most do not move; nutrients gained by photosynthesis (Autotrophic feeders); store food as starch |
General features of Animalia | Largest kingdom. Multicellular; nuclues and membrane bound organelles (NO cell walls). Move with aid of cilia, flagella or contractile proteins - sometimes in the form of muscles. Store food as glycogen; Heterotrophic feeders (ingest nutrients). |
Classification systems were originally based on features that can be observed. Recent changes to classification are..... | evolutionary relationships are studied and DNA is compared. |
Describe the current classification system - the 3 Domain System | Based on differences in rRNA (ribosomal RNA). 3 Domains and 6 Kingdoms. 3 Domains are Eukarya, Archaea and Bacteria. 6 Kingdoms are Protoctista, Plantae, Fungi, Animalia BUT instead of Prokaryotae there are 2 Kingdoms- Eubacteria and Archaebacteria. |
What are Archaebacteria? | "Ancient bacteria"- can live in extreme environments such as hot thermal vents or anaerobic conditions.e.g. Methanogens live in sewage treatment plants and produce methane. |
What are Eubacteria? | "True Bacteria", found in all environments. Most bacteria are in this Kingdom. |
What is PHYLOGENY? | Evolutionary relationships between organisms. Study of phylogenetics can show which group an organisms is related to and how closely it is related. |
What is a phylogenetic (or evolutionary) tree? | Diagram representing evolutionary relationships between organisms. Branched diagrams which show that different species have evolved from a common ancestor. The earliest species are found at the base of the tree. Much evidence gained from Fossil Record. |
How do you interpret phylogenetic trees? | Tips represent groups of descendant organisms (usually species). NODES (points where new lines branch off) represent common ancestors. Two descendants from same node are called sister groups. Closer the branches, the close the evolutionary relationship. |
Advantages of Phylogenetic classification. | 1. Uses phylogeny to confirm whether classification (Linnaean)groups are correct. 2. Produces a continuous tree-do not have to put things in a group that they might not exactly fit. 3. Hierarchy of Linnaean system can be misleading. |