Chapter 6 - Old And New Species

Question 1

What are the different ways fossils may be formed

Answer 1

• from hard parts of animals that don’t decay easily (bones, teeth, shells)
• from para of organisms that have no decayed because some of the conditions for decay are absent
• when parts of organism are replaced by other materials (minerals)
• as preserved traces of organisms, footprints, burrows

Question 2

What does extinction mean

Answer 2

A species that once existed has completely died out

Question 3

Why does extinction occur

Answer 3

• new disease
• new predator
• new competitor
• catastrophic event (earthquake)
• environment changes over geological time

Question 4

What are the two theories of why dinosaurs became extinct

Answer 4

• collision of giant asteroid caused huge fires, earthquakes. Dust which rose masked sun causing darkness and lower temperatures. Temp fell and plants couldn’t grow
• sea ice melting and cooling sea temp. Therefore less plankton and less food

Question 5

What is geographical isolation

Answer 5

A group of species become isolated. The organisms may be exposed to different conditions, food availability or predators. Natural selection will occur to create different characteristics and so they become two different species when they are unable to successfully interbreed

Question 6

What is speciation

Answer 6

When two population can no longer interbreed and produce fertile offspring

Question 7

How old is the earth believed to be and when is it believed that life began

Answer 7

It is believed that the earth is about 4500 billion years old and that life began about 3500 billion years ago