What is the meaning of selectively permeable?

Several bird species feed in a certain species of tree. each bird species feeds in a different part of the tree. which statement is true of these bird species? a. they have adapted to different niches due to competition b. they have a carnivorous relationship with the tree species. c. they have adapted to different niches due to predation d. they have a symbiotic relationship with the tree species.

When a human or animal consumes food, the carbon in that food is most likely to be converted into which of the following elements? a. carbon remains carbon b. nitrogen c. oxygen d. hydrogen

Explain how sequences of amino acids in proteins can be used to reveal relationships among organisms.