B2.6 Flashcards
When do scientists think life on Earth began?
Somewhere between 3-4 billion years ago.
Which is the most common type of fossil?
Harder parts of the animal or plant.
Why are fossils such important evidence for the way life has developed?
They are the remains of organisms that are preserved in rocks etc.
What were most of the very earliest forms of life?
Soft-bodied organisms.
Why is there no valid evidence of how life began?
There is no fossil record of the earliest life forms on Earth.
What do fossil records help us to understand?
How much organisms have changed since life developed on Earth.
What is extinction?
The permanent loss of all the membranes of a species.
How has the change in conditions affected new species?
When they evolve they are better suited to survive the new conditions.
Name 3 changes in the environment that would cause extinction:
- new predators
- new diseases
- successful competitors
3 ways in which living organisms can change an environment and cause extinction:
- new predators can wipe out unsuspecting prey animals very quickly
- new diseases can bring species to the point of extinction
- one species can cause another to become extinct by successful competition
Why are Ice Ages often linked to extinctions?
Living organisms will have a lack of food and will be too cold to breed.
What is mass extinction?
Relatively sudden global decrease in the diversity of life forms.
What is geographical isolation?
When two populations become physically isolated by a geographical feature.
What happens when a population becomes isolated from another?
The conditions they are living in are likely to be different.
What is endemic organism/area?
When a species evolves in isolation and is found in only one place in the world.
