Fossils and Speciation Flashcards
What are fossils?
Remains of organisms from many years ago
What parts of an organism fossilise?
Hard parts (teeth, bones and shells)
What are 3 ways fossils are formed?
Gradual replacement by minerals
Form casts and impressions
Preservation
What are some theories of how life began?
Primordial soup
Under the sea
Comet brought simple organic molecules
Why can’t these hypotheses be supported/disproved?
Lack of valid and reliable evidence
Why aren’t there fossils of early organisms?
They were soft-bodies so they decayed before a fossil was formed
What is an extinct species?
A species that no longer exists
What is a species?
A group of similar organisms that can reproduce to give fertile offspring
What is speciation?
The development of a new species
When does speciation occur?
When populations of the same species become so different they can no longer breed to produce fertile offspring
What is isolation?
When populations of the same species are separated
What is the most common cause of isolation?
Physical barrier (like mountains or floods or earthquakes)
Why will the different populations have different characteristics?
Conditions will be slightly different
Natural selection and different alleles
What are 6 reasons for a species to go extinct?
Environment changes, New predator, New disease, New competitors, Catastrophic event, Speciation
