Mutualism
Define mutualism in one sentence.
A relationship in which both species benefit from the interaction.
Define commensalism in one sentence.
A relationship in which one species benefits while the other is neither helped nor harmed.
Define predation in one sentence.
An interaction in which one organism, the predator, captures and consumes another organism, the prey.
Define competition in one sentence.
An interaction in which organisms compete for the same limited resources.
Define parasitism in one sentence.
A relationship in which one organism, the parasite, benefits while the host is harmed.
Name one real example besides clownfish/anemone.
Ex. Bees and flowers; mycorrhizal fungi and plant roots; bacteria in the human digestive system and humans; lichen (alga + fungus), etc.
Why are barnacles on a whale commensalism and not mutualism?
The barnacles benefit by gaining transportation and access to food, while the whale is generally neither significantly helped nor harmed.
Name the predator and prey in: owl and mouse.
Predator: owl. Prey: mouse.
Name 3 resources two species might compete for.
Ex. Food, water, sunlight, space, shelter, nutrients, or mates.
Why doesn't a parasite usually kill its host quickly?
Because the parasite depends on the host for resources or survival; killing the host too quickly can eliminate the parasite's source of food or habitat.
Bees and flowers: who gains what, specifically?
Bees gain food (nectar/pollen), while flowers gain pollination, which helps reproduction.
Give an example of a plant showing commensalism.
Ex. An epiphytic orchid growing on a tree; the orchid gains support and access to light while the tree is not significantly affected.
Explain one adaptation prey use to avoid predation.
Ex. Camouflage allows prey to blend into their surroundings and become harder for predators to detect. Other valid answers: mimicry, hiding, defensive structures, warning coloration, speed.
Explain the difference between competition and predation.
Competition occurs when organisms seek the same limited resource, while predation occurs when one organism captures and consumes another organism.
Give an example of a parasite and its host.
Ex. Tick → dog/human; flea → dog/cat; tapeworm → human; mosquito → human.
Explain why a mutualistic relationship can still break down if one species disappears.
Because the organisms depend on the interaction for benefits; if one species disappears, the other may lose an important resource or service and be negatively affected.
A bird nests in a tree without harming it — but the tree later can't grow because of the nest. Is still commensalism? Justify.
No. If the tree is actually harmed, it is no longer commensalism because the second species is negatively affected. (Tree can´t grow normally)
Is a spider eating a fly caught in its web predation? Justify using the definition, not just intuition.
Yes. The spider is the predator because it captures and consumes the fly, which is the prey. Therefore, the interaction meets the definition of predation.
Two plant species have overlapping root systems in dry soil. Is this competition? What evidence would confirm it?
It could be competition. Evidence would include both species using the same limited water/nutrients and showing reduced growth or resource availability when growing together compared with when they grow separately.
A mosquito bites a human once and flies away. Parasitism or predation? Defend your answer.
It is generally classified as parasitism because the mosquito obtains a resource from the human while the human is harmed. The mosquito does not capture and consume the human as prey.
Species A provides food to Species B. In return, Species B protects Species A from predators. Researchers remove Species B, but Species A survives and reproduces normally. Is the relationship necessarily mutualism? Explain.
Not necessarily. Although both species appear to benefit, the evidence must show that both species actually depend on or gain a benefit from the interaction. If Species A is unaffected when Species B disappears, the relationship may not be mutualistic for Species A.
Species A benefits from living with Species B. When Species A is removed, Species B's survival decreases. Can this relationship still be classified as commensalism? Explain.
No. If Species B is negatively affected when Species A is removed, then Species B is receiving an important effect from the interaction. Therefore, the relationship is not +/0 and should be reconsidered as another type of interaction, such as mutualism if both species benefit.
A predator captures prey but does not immediately kill it. Instead, it feeds on the prey over several days and eventually kills it. Is this predation or parasitism? Defend your answer using the characteristics of both relationships.
It is predation, assuming the organism is actively capturing and consuming its prey. Predation generally involves a predator obtaining food by capturing another organism. Parasitism involves a parasite living in or on a host and obtaining resources from it over an extended association.
Two plant species grow separately and both grow normally. When planted together, Species A grows poorly while Species B grows normally. Both species use the same limited mineral from the soil. What type of relationship is most likely occurring? What evidence supports your answer?
Competition. Both species require the same limited resource, the mineral. When they grow together, Species A experiences reduced growth, suggesting that the species are competing for that resource.
A parasite is found living on a host. Scientists discover that when the parasite is removed, the host becomes healthier, but the parasite dies within a few days. Does this evidence support parasitism? Explain why.
Yes. The evidence shows that the parasite benefits from the host while the host is harmed by the interaction. The parasite's dependence on the host is also consistent with parasitism.