Tom wants to incorporate more organic practices on his farm. he wants to enrich the nitrogen content of his soil through biological fixation without adding chemical fertilizers. which plants are best suited for this purpose?

There are multiple factors which controls the nitrogen and other nutrients presence in soil for the good growth of plants, one of them is the selection of right kind of plants which fixes nitrogen more efficiently than others.

These are the few plants which are good nitrogen fixing plants such as:

-Lupines, cowpea, fava bean, alfalfa  

-Tall trees such as black alder, black locust and empress tree  

-Shrubs and shrt trees such as autumn olive, Gumi, Siberieam pea shrub, Russion olive and Sea berry

the two answers are a, the population of birds with large beaks will increase on the island, and c, the trait for large beaks will be passed on to future generations through natural selection. the reason for that is because if the birds that have beaks developed for eating small seeds lose all of their food, they will go hungry and eventually starve because they physically cannot eat the large seeds, therefore making the population of large beaked birds higher. also, if the trait of large beaks are dominant on the island over small beaks, then over time the large beaked birds will reproduce more and more, while the smaller beaked birds will reproduce less and less because they can't survive with the food provided. that leads to the trait of small beaks disappearing and the trait of large beaks taking over the island.

the wetland preservation movement began in the u.s. in earnest with the clean water act (cwa) of 1972. although not specifically written to protect wetlands, the cwa is comprised of a series of regulations designed to prevent pollutants from contaminating u.s. waters.