Evidence for Evolution Flashcards
When an organisms dies its flesh will ________ leaving behind the _________ . The skeleton becomes covered in sand, _________ or clay and becomes buried. The skeleton then becomes replaced with __________ over a long period of time. This is mineralisation.
As the rock ____________ the mineralised fossil may be revealed.
decompose
skeleton
mud
minerals
erodes
Sometimes when an organism dies it may not decay - this occurs if the _________ for decay are not correct. For example a lack of___________ or a very low ___________ .
conditions
oxygen
temperature
Why are there gaps in the fossil record?
Because many early forms of life were soft-bodied, which means that they have left few traces behind.
Remaining traces may have been destroyed by geological activity.
There are many different species of bird on the Earth today.
Describe how these different species may have evolved from an ancestor such as Archaeopteryx. (4)
Isolation of different populations and different environmental conditions between locations.
So mutations occur, then natural selection occurs.
Favourable alleles are passed on,
until eventually different populations are unable to successfully breed with each other.
Explain how a fossil is formed: (3)
The organism was covered in sediment.
Then the soft parts decayed.
Then the bones were replaced by minerals.
Who proposed the theory that changes in an organism during its lifetime can be inherited?
Jean Baptiste Lamarck.
Explain how the Japanese rat snake evolved to be different from the Texas rat snake: (4)
There are many ________ colours of snakes. Different colours are controlled by different _______.
Being green means they are __________, those ___________ will be able to avoid being eaten. ____________________ will ___________ for green colouration.
different
alleles
camouflaged
camouflaged
Survivor’s offspring
inherit alleles
Give one reason a species might become extinct?
Because of changes to the environment.
