B2 topic 3 evolution

Question 0

What do fossils found in rock layers tell us?

Answer 0

What the organism looked like and how long ago they existed( how deep down)
How they’ve evolved (comparing fossils over time)

Question 1

Evolution

Name the three ways fossils are formed

Answer 1

Gradual replacement- teeth and shells don’t decay and last ages when buried. They will be replaced by minerals forming a rock substance shaped like the original. It is eventually dug up
Casts and impressions- when an organism is buried in soft material like clay the clay will harden and the organism decays leaving a cast.
Preservation- when no decay happens due to unsuitable conditions for microbes to work.

Question 2

Why is the fossil record incomplete

Answer 2

Very few organisms turn into fossils
Soft tissue decays completely
Undiscovered fossils

Question 3

How does the pentadactyl limb provide evidence or evolution

Answer 3

This is a limb with 5 digits and it’s found in many species. In each species the bone structure is similar but it has a different function. The similar bone structure shows we he have all evolved from a common ancestor