Leeches are parasitic because they suck blood not giving any benifit but harm.
Explanation:
What would cause a tree to die?
There are 5 factors to which a tree eventually succumbs: death from its environment, death from harmful insects and diseases, death from a catastrophic event, death from age-related collapse (starvation) and of course, death from harvest.
I hope this helps
Wind energy because it's natural and some places dont have electricity.
The above is an example of a polygenic trait. This implies every prevailing allele "includes" to the declaration of the following predominant allele. As a rule, qualities are polygenic when there is a wide variety in the characteristic. For instance, people can be a wide range of sizes. Stature is a polygenic characteristic, controlled by no less than three qualities with six alleles.