Fossils Flashcards
How can fossils form in rocks
From gradual replacement by minerals
From casts and impressions
From preservation in places where no decay happens
How are fossils formed from gradual replacement by minerals
Things like teeth and bones that don’t decay easily can last a long time when buried
They are replaced by minerals as they decay and form a rock like substance shaped like the original hard part
The surrounding sediments also turn into rock but the fossil remains distinct and eventually Someone digs it up
How are fossils make from casts and impressions
When soft material hardens around an organism and the organism decays to leave a cast eg an animals burrow or footprints
Where does preservation in places where no decay happens happen
In amber and tar pots where there’s no oxygen or moisture so decay microbes die
In glaciers
Peat bogs
When does speciation occur
When populations of the same species become so different they can no longer produce fertile offspring
What leads to speciation
Isolation and natural selection
Who came up with the theory of speciation
Alfred Russel Wallace
How are antibiotic resistance strains caused
Bacteria sometimes develop random mutations in their DNA and thus leads to changes in the characteristics so it could be less affected by an antibiotic and an antibiotic resistance strain can occur when the gene gets more common
Why can antibiotic resistance strains form quickly
Because bacteria are so rapid at reproducing
Why does the population size of the antibiotic resistant strain increase
Because it’s able to survive and live longer and reproduce many more times
Why is it important that doctors only prescribe antibiotics when they really need to
Because it’s not the antibiotics actually causing resistance - they create a situation where naturally resistant bacteria have an advantage and so increase in numbers
What is the Linnaean system
Living things are first divided into kingdoms and these are subdivided into smaller and smaller groups
They are grouped according to their characteristics and structures
What is the three domain system
Organisms are split up into 3 large groups called domains
Archaea
Bacteria
Eukaryota
What are archaea
Primitive bacteria found in extreme places like hot springs
What are bacteria
True bacteria like e.coli
