B15.5-.10 Genetics and Evolution Flashcards
What are fossils?
remains of organisms from millions of years ago that can be found in rocks, ice and other places
Ways a fossil is formed?
- absence of decay due to conditions needed for decay not being there (eg. too low temp, oxygen)
- the hard parts of the animal being replaced with minerals as they decay and they become part of the rock
- preserved traces of an organism, ie. footprints, droppings etc.
Reasons the fossil record is incomplete?
- many of the earliest life form on earth were soft-bodied and so left little fossil trace
- the majority of any of the earliest fossils would have been destroyed by geological activity (eg formation if mountain ranges, volcanoes, earthquakes…)
- most organisms didn’t fossilise as conditions weren’t right
- undiscovered fossils
Factors that may cause extinction? (6)
- new predators
- new diseases
- new, more successful competitors
- changes to environment
- single catastrophic event
- collisions with asteroids
D. Extinction?
the permanent loss of all members of a species
Most recent mass extinction?
the dinosaurs
How did asteroid kill dinosaurs? (5)
caused:
- tsunamis
- earthquakes
- wildfires
- landslides
- dust would have made planet dark and caused global decrease in temp –> global winter
Evidence for asteroid theory?
- crater in mexico containing a layer of rock formed by crater debris
- deep below crater, scientists found lots of iridium which is only formed when rock is hit with a massive force
Why can bacteria evolve rapidly?
because they reproduce fast
D. Classification?
the organisation of living things into groups according to their similarities
Who created the classification system we use today?
Carl Linnaeus
D. Species?
smallest group in Carl’s system. members of the same species are very similar - a group of organisms that can breed together to produce fertile offspring
D. Archaea?
one of 3 domains, containing primitive forms of bacteria that can live in many of the extreme environment of the world
5 kingdoms that used to be used?
prokaryotes, protista, fungi, plants, animals
D. Eubacteria?
normal bacteria (like stuff grown in labs at school)
How were the 6 kingdoms made?
prokaryotes were divided into archaea and eubacteria
Main kingdoms in the origional Linnaean classification system?
animals and plants
Main kingdoms in the mordern classification system?
protista, fungi, plants, animals,archaea and eubacteria
3 Rules for writing scientific names?
- first part of name = genus, written with capital letter
- second name = species, written in lower case
- names are underlined if handwritten and in italics if typed
What did Linnaeus classify things into?
kingdom, phylum, class, order, family, genus, species
binomial system?
genus and species
D. Domain?
new higher level of classification above the kingdom
3 domains (currently used) proposed by Woese? eg's
- Archea - primitive bacteria
- Bacteria - true bacteria
- Eukaryota - plants animals fungi protists
Archea?
Primitive form of bacteria, including extremophiles. Contains 1 kingdom, archaebacteria
Bacteria?
True bacteria and the cyanobacteria, bacteria-like organisms that can photosynthesis
Eukaryota?
organisms with cells that contain a nucleus enclosing genetic material. 4 kingdoms: protista, fungi, plants and animals
D. Evolutionary trees?
models used to explain evolutionary links between groups of organisms
Linnaeus’ system? (order in)
kingdom - phylum - class - order - family - genus - species
2 parts of binomial name?
genus, species
Why were new models of classification proposed?
- microscopes improved so scientists knew more about cells
- biochemical processes became better understood
Who proposed the three-domain system?
Carl Woese
