Which phrase is not an example of intercellular communication? 1. chemical signal from pituitary gland to adrenal gland
2. electrical signals pass between heart cells
3. chemical messengers dock onto receptors of adrenal gland
4. a vesicle encloses over a nutrient molecule

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.