Which type of receptor binds to ligands that cannot enter the cell?

What is the name for a substance formed in a chemical reaction

Astudent analyzed ears of corn that demonstrated two traits in the f2 kernels, purple or white colors and smooth on wrinkled shapes. a tabulation of 135 individual kernels gave the following results: purple and smooth = 75 white and smooth = 28 purple and wrinkled = 24 white and wrinkled = 8 what would be the only phenotype present in the f1 ger

In which of the following relationships is one organism always benefited while the other organism is always harmed