B2.8 Flashcards
What might cause plants and animals to die out
Changes in the environment
What do fossil records show
That new organisms arise, flourish and then after become extinct
Changes that lead to the formation of new species
Where does the uncertainty come from when looking at organisms that lived long before us
Lack of enough valid and reliable evidence
What evidence comes from fossils
Early forms of life
What are fossils
The remains of organisms from many years ago and are found in rocks
How can fossils be formed
Hard parts of animals that don’t decay easily
Conditions for decay were absent
Parts of organisms replaced by other materials
Footprints , burrows and rootlet traces
What does it mean when many early forms of life were soft bodied
That they have left few traces behind
What were many traces of early forms destroyed by
Geological activity
What can u learn from fossils
How much or how little organisms have changed as life developed on earth
What can extinction be caused by
Changes in environment New predators New diseases More successful competitors Catastrophic event Cyclical nature of speciation
New species arise as a result of
Isolation
Genetic variation
Natural selection
Speciation
What is speciation
The development of a new species
What is a species
A group of similar organisms that can produce fertile offsprings
How does isolation cause a new species to arise
Two populations of a species become separated
How does genetic variation cause species to arise
Each population has a wide range of alleles that control their characteristics
