Fossils

Question 1

What are fossils?

Answer 1

The remains of plants or animals.

Question 2

How are fossils formed by gradual replacement? (3 points)

Answer 2

1) teeth, shells, bones etc which don’t decay easily last a long time when buried
2) they are eventually replaced by minerals forming a rock like substance
3) they get surrounded by sediment, but the fossil stays distinct inside the rock until it gets dug up

Question 3

How are fossils formed from casts and impressions? (2 points)

Answer 3

1) fossils are formed when an organism is buried in a soft material like clay, which later hardens around the organism, leaving a cast of itself
2) footprints can be pressed into these materials when soft, leaving an impression when it hardens

Question 4

How are fossils formed by preservation? (4 points)

Answer 4

1) an organism is put somewhere where no decay happens
2) in amber and tar pits there is no oxygen or moisture so decay microbes can’t survive
3) in glaciers it’s too cold for the decay microbes to work
4) bogs are too acidic for decay microbes

Question 5

Why does no one know how life began?

Answer 5

There is a lack of valid and reliable evidence, this is because scientists believe that early organisms were soft-bodied, which decays easily. Also, fossils formed millions of years ago may have been destroyed by geological activity.