Old and new species Flashcards
Why are some fossils destroyed over time
Due to geological activity which breaks them up or wears them away
How can a new predator cause extinction of a species
It eats all the animals
Suggest another factor which could have caused the dinosaurs to die out
I knew disease being introduced into the population it is unlikely to be a new predator because dinosaurs were at the top of the food chain
How do populations become isolated
Islands break away from the mainland, you Rivers form, mountain ranges or craters separate them
What is meant by genetic variation
The wide range of alleles that control the characteristics in a population
Why can scientists not be exact about when life began on earth
Because there is little repeatable or reproducible evidence left
What are fossils
Fossils are the remains of organisms from many years ago which are found in rocks
What can we learn from fossils
How different organisms have changed as life develops on earth
What can cause extinction of a species
A new disease may kill all members of the species
A new predator may be introduced
A single catastrophic event may occur e.g. a volcanic eruption
Natural changes in species overtime
How do scientists think the dinosaurs became extinct
The collision a giant astroid caused earthquakes-the dust which arose masked the sun causing darkness and lower temperatures- plants could not grow and temperatures fell
How old is the earth
About 4.5 billion years old
What are the stages of creating a new species
Two species are separated by a geographical isolation. There is genetic variation in the two populations and alleles are selected which give and advantage (survival of the fittest) The organism is best suited to their environment survive and breed passing on their alleles finally the two species become so different that they can no longer interbreed
Name a hard part of an animal which will not Decay easily
Bones, teeth, shells, claws
