B2- Old and New Species

Question 1

How can fossils be formed?

Answer 1

• Hard parts of animals that don’t decay easily.
• Parts of organisms not decayed because decay conditions absent (e.g: preserved in ice).
• Parts of organisms replaced by other materials as they decay.
• Preserved traces of organisms (e.g: footprints).

Question 2

Why are some fossils destroyed over time?

Answer 2

• Many early life forms had soft bodies so few traces were left behind.
• Traces left were likely to have been destroyed by geological activity.

Question 3

Define extinction.

Answer 3

Extinction means that a species which once existed has completely died out, so none survive.

Question 4

Why might extinction occur?

Answer 4

• New disease may kill all members of a species.
• Environmental change over long time.
• New predator may evolve or be introduced.
• New competitor may evolve or be introduced so original species have little to eat, etc.
• Single catastrophic event destroys habitat.
• Natural change in species over long time.

Question 5

Suggest one factor which could have caused the dinosaurs to die out.

Answer 5

Possible answers:

1. Collision of giant asteroid caused huge fires, earthquakes, landslides and tsunamis.
2. Dust which rose masked sun, causing darkness and lower temp➡️plants couldn’t grow and temperatures fell.
3. Extinction slower process due to sea ice melting and cooling sea levels➡️less plankton➡️less food available.

Question 6

What are fossils?

Answer 6

Fossils are remains of organisms from many years ago which are found in rocks.

Question 7

What is meant by the term species? (2 marks)

Answer 7

Organisms that can breed together (1) and can produce fertile offspring (1).