Answer:
1.Gas exchange occurs by diffusion across their membranes.
2.On the contrary, in the closed circulation, the blood is pumped through the vessels separate from the interstitial fluid of the body.
3.maintenance by an organism of an internal balance between water and dissolved materials regardless of environmental conditions.
4.
•The central nervous system is made up of the brain and spinal cord.
•The peripheral nervous system is made up of nerves that branch off from the spinal cord and extend to all parts of the body.
5.exocrine glands secrete substances into a ductal system to an epithelial surface
6.Natural barriers include the skin, mucous membranes, tears, earwax, mucus, and stomach acid.
pa brainliest po salamat:))
