3 - cell & evolution

adaptation & natural selection

• characteristic that helps an organism survive and reproduce

• include: structures(physical body parts), behaviours for finding food, mate, protection and for moving from place to place

snake

jaw that can unhinge to swallow prey whole

kangaroo

large ears to hear predators

spider

can easily sense vibrations in the ground

monkey

have opposable thumbs for grasping items

cheetah

has spots that camouflage them from predators

elephant

large tusks for defence

Aristotle

• made Origin of species (Hypothesis 1)

• believed all plants and animals had been placed on Earth at its beginning and not have changed

Hypothesis 2

• 2 hypothesis

• Lamarck and Darwin

Lamarck’s Theory

1. Law of Use&Disuse

   • more often a body part is used, the more developed it will be

2. Inheritance of Acquired characteristics

   • more developed traits will pass onto their children more strongly

August Weismann

Disproved Lamarck’s theory; cut the tail off of 20 generations of parent mice and found out there was no change

Darwin’s Theory of evolution

• happens because of natural selection

4 key conditions for natural selection

1. Struggle for survival

2. inheritable variation

3. Variation of fitness

4. Lots of time

“struggle for survival”

competition between living things to survive

“Inheritable variation”

• within a population, organisms exhibit differences due to variations in the GENES

• requires inheritable trait; can be passed down to offspring

“variation of fitness”

organism’s ability to produce offspring, organism must stay alive to pass on the genes

“Lots of time”

requires time for “gradual change” in the population for the advantageous trait