Explain ways in which the alveoli are adapted to increase the
efficiency of gas exchange.​

Which class of organic compounds makes up the channels and pumps that move materials from one side of the cell membrane to the other? a.) carbohydrates b.) lipids c.) proteins d.) nucleic acids

Which of these is not a function of some membrane proteins ? a. allowing polar molecules to enter the cell b. recognizing other types of cells c. receiving messeges from other cells b. carrying messages to oher cells

According to theories of how life began, how did early organic molecules begin to separate from the outside world? a: specialized enzymes were required b: chains of amino acids created a barrier c: formation of microspheres or vesicles d: rna catalyzed the formation of membranes