fossils

Question 1

how are rocks formed(3)

Answer 1

• gradual replacement:things that dont decay last a long time
• casts:fossils may form when an organism is buried in soft material
• preservation: in places where no decay happens they are formed eg.in glaciers where its too cold for enzymes to work

Question 2

why is the fossil record incomplete?(2)

Answer 2

early organisms were soft bodied and soft tissue tends to decay completely

some fossils may have been destroyed by geological activity

Question 3

why do species become extinct

Answer 3

• environmental changes
• new predator
• new disease
• catastrophic event

Question 4

whats speciation?

Answer 4

development of new species

Question 5

how does isolation lead to speciation?(5)

Answer 5

• population gets separated by phsical barrier
• natural selection happens:those who are best adapted have a better chance of survial
• those with successful characteristics survive and breed
• the beneficial characteristics are passed on to the next generation
• this creates a new species who are unable to breed successfully