Chapter 20/Section 3 Notes
1. All living things must be able to adapt to the environment around them in
order to survive.
2. Natural Selection is like “survival of the fittest”. Those that develop unique
characteristics needed to survive in a particular environment will survive and
produce offspring that will be able to survive.
3. Three major types of interactions among living things: competition,
predation, and symbiosis
4. Different species can share the same habitat and food requirements as long
as they do not occupy exactly the same niche.
5. When there is not enough food, water, and shelter to sustain all the
organisms in an area, some species must either move or they will die.
6. Predation is both negative and positive. If there are more predators than a
particular type of prey, the numbers of that prey may become too low and
there is not enough food for the predators plus that prey (species) dies out.
If there is more of a particular prey (species) that predators, the predators
help to keep that species thinned out so that there won’t be a diminished
food source for the prey species.
7. Defense Strategies: Mimicry, False Coloring, Camouflage, Warning
Coloring, Protective Coloring
8. Three types of Symbiosis: Mutualism, Commensalism, Parasitism
Mutualism example: A bee lands on a flower and eats nectar from the
flower. The bee gets pollen on its feet and wings when it brushes against the
flower’s petals. The bee flies to another flower for more food and deposits
the pollen from its feet and wings which pollinates the flower.
Commensalism example: A bird builds a nest in a tree. The tree is not
harmed nor does it benefit from the nest but the bird benefits by having a
nest in the tree away from predators on the ground that would kill it.
Parasitism example: A tick on a dog – The tick sucks blood from the dog
which causes the dog to lose nutrients from the blood. The tick benefits and
the dog is harmed.