You had assignment that is over due but you need extra time what is a good excuse to tell your teacher why you need extra time work on the assignment

i suggest saying you've been ill, or have had personal/family issues going on. if you say the second option, it is a bit invasive for the teacher to ask what so they shouldn't, but have something ready just in case. both of these have gotten me extensions before. :)

a signal molecule locks to a receptor protein (like lock and key),causes shape change in receptor then creates a specific reaction inside the cell that eventually triggers the cell response. State where signal receptors may be located in target cells.