Which substance on the plasma membrane identify chemical signals from outside the cell?
question 32 options:

carbohydrate chain

cholesterol

membrane protein

transport protein

carbohydrate chain identify chemical signals  and proteins transmit the signals inside the cell.

Explanation:

Phospholipid is  a special type of lipid that is responsible for the structure of the cell membrane.  Cholesterol is a nonpolar substance that is used to prevent the fatty acid tails from sticking together and preventing substances from passing. The transport protein move needed substances or waste materials through the plasma membrane . Carbohydrate chains define the cell's characteristics and help cells identify chemical signals.

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.