Food Webs and Energy
Grass and shrubs make their own food from sunlight. This is their job in a food web.
What is a producer?
The biggest population an environment can hold for a long time.
What is carrying capacity?
A lion hunts a zebra. The lion is this, and the zebra is this.
What are the predator and the prey?
A survivorship curve shows how many are still alive at each of these.
What is age (each stage of life)?
Both species win. Name the relationship.
What is mutualism? (+/+)
Grass, then rabbit, then hawk. The rabbit eats plants, so it is this kind of consumer.
What is a primary consumer?
Food, water, space or predators that keep a population from growing bigger.
What is a limiting factor?
The hare population goes up. A little later, the lynx population that eats hares does this.
What is goes up too? (the predator follows the prey)
Few babies, lots of care from the parents, most live to old age. Elephants and humans have this type.
What is Type I?
One species wins and the other is hurt. Name the relationship.
What is parasitism? (+/-)
The 10% rule: the plants hold 5,000 units of energy. This much energy reaches the animals that eat them.
What is 500 units? (10% of 5,000)
Rabbits are crowded, so they all fight over the same grass. Competition for food like this is this kind of limiting factor.
What is density dependent? (it gets worse the more crowded they are)
Predators are removed, the plant eaters explode, and they eat the plants down to the dirt. This word for it.
What is overgrazing?
Thousands of eggs, no care, most die very young. Frogs and fish have this type.
What is Type III?
One species wins and the other is not helped or hurt. Name the relationship.
What is commensalism? (+/0)
At every level about 90% of the energy is lost, mostly as this. That is why food chains stop at 4 or 5 levels.
What is heat? (plus waste and staying alive)
A hurricane kills island birds the same way whether there are 10 birds or 1,000. This kind of limiting factor.
What is density independent? (it does not matter how crowded they are)
Two packs hunt the same deer. When one pack grows, the other pack shrinks. Name this relationship.
What is competition?
Birds and small mammals have the same chance of dying at every age. Their curve is this type, a straight line down.
What is Type II?
A bee drinks nectar and carries pollen to the next flower. Name the relationship and say what each one gets.
What is mutualism? The bee gets food, the flower gets pollinated.