This is b'coz it creates variations in the characteristics of organisms =)
The significance of the mutation of living things is that mutation allows species to adapt to their environments over time (variations in human skin color are a good example of this). It is also a major part of Darwin's all but proven Theory of Evolution.
what is advantage of covalent bonds in living things
Well its evolution of course, but that happens when there is random mutation to a specific gene, e.g colour. if this gene mutation helps improve the living things chances of survival it is passed on to their offspring.
its called survival of the fittest. if by some chance there is a mutation during a time of change in a living things surroundings and the mutation helps that living thing survive while other living things not "fit" to survive that change will have a lesser chance of surving. If that mutation passes on to the mutated living things children then that is what leads to evolution in living things.
population
No you do not. In taxonomy, a populatio strictly applys to only living things. nonliving things are not included in taxonomy.
Ecosystem
mutation in the DNA order and sexual reproduction of the favorable animal in the ecosystem.
determinate
A pile of clam shells is not a population because they are not living things so they can not be a population
Many things: ionizing radiation, free radicals, various chemicals, copying errors, retroviruses, etc.
A population in a community means the specific kind of organism (plants and animals) living in a community (all the living things in an ecosystem)