<span>1. Mutualism is a type of relationship that can be seen between two individuals of two different species to obtain benefits for both of individuals.
Examples : Coral polyps and zooxanthellae
bee and flower
Lichens
Rhizobium and root nodules
Ungulates and bacteria which live in their intestines
</span><span>2. Commensalism (this is the correct word) is a type of relationship between two organisms which belonged to two different species that one individual obtains benefits while other doesn't have any harm or benefit.
Examples : Remora and sharks
Orchids and trees
Pseudoscorpions and Beetles
Cattle Egrets and Livestock
hermit crab and sea anemone
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3. Parasitism is a relationship between two organisms of two different species where one individual (parasite) gets benefits by harming other individual (host).
Examples : <em>Cuscuta</em> (parasite)<span> and angiosperms (host)
Parasitic viruses (parasite) and human (host)
Tape worms (parasite) and pigs (host)
Flukes (parasite) and human (host)
Parasitic bacteria (parasite) and human (host)</span>
Easy. Answer is oxygen because it says which one was missing before any life was on earth. And in order to have life on earth you need oxygen!
:)
The energy of the ecosystem can be best described as option C. The amount of energy entering an ecosystem from the Sun is equal to the amount used by organisms plus the amount lost as heat.
