APES 1: Organism Interactions & Feedback

Hermit crabs

________ make homes in shells abandoned by snails.

feedback loop

a feedback process where an output of matter, energy, or information is fed back into the system as an input and leads to changes in that system

positive feedback loop

causes systems to change further in the same direction; increases change to a system

negative feedback loop

causes systems to change in the opposite direction; decreases change to a system

examples of a positive feedback loop

melting of a polar ice cap, increased erosion due to decreasing vegetation

examples of a negative feedback loop

reproduction -> overgrazing -> less reproduction

competition

compete for available resources (food, mating partners, etc.); occurs between both the same and different kinds of organisms

predation

hunt and kill other organisms to supply their energy needs; occurs between different kinds of organisms

symbiosis

live in close association with another kind of organism; occurs between different kinds of organisms

cooperation

live together and help each other; occurs between the same kind of organisms

resource

anything needed by an organism for life (ex. nutrients, water, light, space)

limiting factor

a nutrient in short supply or one that cycles slowly (LIMITS the growth of the population)

mutualism

a relationship where both organisms benefits (ex. insects transfer pollen between plants as they gather nectar for food)

commensalism

a relationship where one organism benefits; the other is neither harmed nor helped (ex. hermit crabs make homes in shells abandoned by snails)

parasitism

a relationship where one organism benefits; and the other is harmed in some way (ex. ticks feed on dog’s blood)