Answer:
The key to the adaptation of living beings on the planet is the adaptation to abiotic factors such as temperature, light, salinity, humidity; and to biotic factors, which are represented by the action of the other organisms.
Explanation:
Multicellular organisms can be much larger and more complex. This is because the cells of the organism have specialised into many different types of cells such as nerve cells, blood cells, muscle cells all performing different functions.
Functions of cell surface Receptors .
most ligands responsible for cell-cell signaling ( including neurotransmitters, peptide, hormones, and growth factors) bind to receptors on the surface of their target cells.
I believe it is the Nitrogen cycle although all of the cycles use bacteria. Only nitrogen requires nitrogen fixing bacteria to keep the cycle going.
The answer or complement is D.unattractive
