D
Only eukaryotic cells have membrane bound organelles. Prokaryotes organelles just float in the cytoplasm.
Answer:
What can be noticed about the ligands and their receptor is that the configuration of both coincide, as a key would with its lock, which demonstrates the specificity of a receptor by its ligand.
Explanation:
A <u>ligand</u> corresponds to a molecule considered a signal or a messenger, while the <u>receptor</u> is a protein on the cell surface, with the capacity to accept a ligand.
Ligands and receptors constitute pairs that complement each other, so that <u>each receptor can bind to a specific ligand</u>, similar to what happens with a key and a lock.
Once the ligand-receptor complex is formed, changes occur inside the cell, which define a certain effect.
Answer:
air
Explanation: without air you can cant even live
