1.Interactions between individuals of different types of organisms in an ecosystem are usually called symbiosis. The effects of symbiosis can be positive (beneficial for organisms) or negative (some of the organisms in the interaction are endangered).
•Mutualism- the interaction that is mutually beneficial (for both)
•Parasitism-the interaction where the parasite benefits and the host is harmed
•Commensalism-the interaction which is beneficial for one organism, but do not affect the other organism (neutral)
Interactions are not always direct (not symbiosis).
•Predation-the short-term interaction where the predator benefits and the prey is harmed.
2.Symbiosis are long-term direct interactions between different types of organisms. Types of symbiosis are mutualism, parasitism and commensalism. Also, symbiosis can be divided into obligatory and facultative subtypes. Organisms in symbiosis can be physically attached one to another or not.
3.Two types of biological interactions are:
•Intraspecific interactions-organisms in interactions are of the same species
•Interspecific interactions-organisms on interactions are from different species
Another division of the biological interaction is:
•Short-term-short in duration; includes predation and pollination
•Long-term interactions-long lasting interaction; symbiosis (parasitism, commensalism, mutualism).
4.Parasitism is type of symbiosis and it is interspecific (between species) interaction, where one organism (the parasite), lives on or in another organism (the host).
Example 1: Tapeworms that attach themselves to the insides of the intestines of cows and get food by eating their partly digested food.
Example 2: Aphids are plant’s parasite which eat the sap from the plants on which they live.
5.The predator is an organism which is part of  a short-term interaction and it benefits while its prey is harmed lethally. The predator, kills and eats another organism.
Example 1: Wolves who hunt and kill bisons.
Example 2: Carnivorous plant that engulfs an insect
6.Prey is an organism which is part of predation interaction. It is an organism that is harmed lethally (killed by the predator). This type of interaction is negative, harmful for them. Bisons are prey for the lions and insects are prey for the carnivorous plants.
7.Mutualism is a symbiotic interaction between two or more species, where species derive a mutual benefit (positive for all the participants).
Example 1: Pollination is an example of mutualism, pollinator eats from the plant and plant gets pollinated by the pollinator.
Example 2: Mycorhiza between plant roots and fungi is also interaction beneficial for both, the plant provides carbohydrates to the fungus in return for primarily phosphate and nitrogenous compounds.
8.Commensalism is a symbiotic interaction which is beneficial for one organism, but neutral for the other (do not affect the other in a positive or a negative way).
Example 1: Remora fish which attach es themselves to larger fish that provide locomotion and food.
Example 2: Â Bird nest on a tree limb can be an example how this relationship can be beneficial for bird and not affect the tree.
9.Predation has a huge role in an ecosystem, since they are on the top of the trophic pyramid. Their influence on an ecosystem has the effects on several trophic levels ('trophic cascade'). Predators regulate herbivore numbers and influence their behaviour, which in turn affects the habitat itself. Removing the native top carnivores would have imbalancing effect on the forest ecosystems. Also, decreased number of top predators would lead to the increase in smaller "mesopredators" that are causing economic and ecological disruption.
10.Competition is the interaction of organisms that vie for a common resource that is in limited supply. In other words, the fitness of one organism is lowered by the presence of another. Resource might be food, water, and territory used by both. It can also be inter- or intraspecific depending on whether the organism are form the same species or not. Species less suited to compete for resources (weaker species) should either adapt or die out. This is an extreme case when one organism becomes extinct from the area. It is more often that “weaker: organism may change its behavior or requirements in order to utilize different resources.
11.Competition is the interaction of organisms that vie for a common resource that is in limited supply. In other words, the fitness of one organism is lowered by the presence of another. Resource might be food, water, and territory used by both. It can also be inter- or intraspecific depending on whether the organism are form the same species or not. By mechanism there are three different types of competition:
•Interference-directly between organism usually via aggression
•Exploitative- indirectly through a common limiting resource
•Apparent -indirectly between two species which are both preyed upon by the same predator.
