Animals, they only have a cell membrane, not cell walls.
I don't know what the answer choices were, though, but I hope this helps.
<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>
Nucleus is the largest organelle in the cell and contains all the cell's genetic information in the form of DNA. The presence of a nucleus is the primary factor that distinguishes eukaryotes from prokaryotes.
Adaptation is a phenomenon that is about adjusting certain features to environmental conditions. Ie. birds are adapted to flight as they possess wings, very efficient lungs etc. or tropical plants are adapted to high temperature and humidity as they modified their photosynthesis process. but if some creature is adapted to the specific habitat or conditions, it is hard for it to manage in another habitat/different conditions. ie. birds are fast in the air but on the ground they are quite weak and prone to predators' attacks.
