B6- Fossils

Question 1

What are fossils?

Answer 1

Remains of organisms from many thousands of years ago, found in rocks

Fossils provide evidence that organisms lived long ago and show how they have evolved over time.

Question 2

How do fossils form from gradual replacement by minerals?

Answer 2

Teeth, shells, bones decay slowly and are replaced by minerals, forming a rock-like substance

The surrounding sediments also turn to rock, but the fossil remains distinct.

Question 3

What are casts and impressions in fossil formation?

Answer 3

Casts form when an organism is buried in soft material like clay, which hardens around it

Impressions can be made by footprints or burrows left in soft materials.

Question 4

What conditions lead to preservation where no decay happens?

Answer 4

Conditions include amber, tar pits, glaciers, and acidic peat bogs

These environments lack oxygen or moisture, preventing decay microbes from surviving.

Question 5

What is a hypothesis about the origin of life?

Answer 5

The first life forms may have originated in a primordial swamp or been brought to Earth on comets

Simple organic molecules could have evolved into complex molecules and then simple life forms.

Question 6

Why is the fossil record incomplete?

Answer 6

Many early life forms were soft-bodied and decayed completely, and geological activity may have destroyed fossils

Tectonic plate movement can crush fossils already formed in rock.

Question 7

True or False: Fossils can tell us about how organisms have changed over time.

Answer 7

True

Fossils provide evidence of evolutionary changes across millions of years.

Question 8

Fill in the blank: Fossils provide evidence that organisms lived _______ years ago.

Answer 8

thousands

Question 9

What are some examples of materials where fossils can be preserved?

Answer 9

Amber, tar pits, glaciers, peat bogs

These materials create conditions that inhibit decay.