Cold front
If you don’t know the compass, just go by Never Eat Soggy Waffles
North East South West
A stable ecosystem is characterized by having a continual input of energy from the sun. This is required in order to sustain or maintain a stable structure. Without proper supply of energy, life would not exist. Hope this answers the question.
Yes, all polypeptides have tertiary structures. All proteins have primary, secondary and tertiary structures. However, quaternary structures only arise when a protein is made up of two or more polypeptide chains. Hope this answers the question. Have a nice day.