Is a lung a living organism? why or why not ?

The concept of keystone species is controversial among ecologists because most organisms are highly interdependent. if each of the trophic levels is dependant on all others how can we say one is most important

Angiosperms are the most successful terrestrial plants. which of the following features is unique to them and account for their success? a. fruits enclosing seeds b. wind pollination c. sperm cells without flagella d. embryos enclosed within seed coats e. dominant gametophytes

He cell membrane forms a protective barrier between the external and internal environments. it is referred to as because it allows some substances to cross more easily than others and blocks other substances from crossing into the cell.