Chapter 6 - Old And New Species Flashcards Preview

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Flashcards in Chapter 6 - Old And New Species Deck (7)
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1
Q

What are the different ways fossils may be formed

A
  • 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
2
Q

What does extinction mean

A

A species that once existed has completely died out

3
Q

Why does extinction occur

A
  • new disease
  • new predator
  • new competitor
  • catastrophic event (earthquake)
  • environment changes over geological time
4
Q

What are the two theories of why dinosaurs became extinct

A
  • 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
5
Q

What is geographical isolation

A

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

6
Q

What is speciation

A

When two population can no longer interbreed and produce fertile offspring

7
Q

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

A

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