Answer: a) relies on the uptake of an external signal molecule from the cell
Explanation: Signal transduction is known as the transmitting of any signal of a molecule from exterior of cell to interior of cell.This technique is termed as critical is taken care of successful transmission of signal effectively and positive result and reception is done by the cell surface receptors.It is also known as cell signalling. Thus,option(a) is the correct option of all.
Porosity
Porosity refers to the space inside the rock that is taken up by pore space.
