The answer is D
One way to remember this is when you are building a bridge there is one piece right in the middle that keeps the whole thing from collapsing that is called the key-stone. If a keystone species goes extinct then the rest of the ecosystem will crumble around it.
Our bodies produce an enzyme called lactase. This enzyme helps our bodies digest lactose (a sugar found in milk). As we age, the amount of lactase our bodies produce decreases. Some people don’t produce as much as others. If you are lactose intolerant, it means your body doesn’t produce a lot of lactase. One option is to drink milk with lactase added to it.
Example: Lactaid
It is called cell division
Hello fellow student! I'm here to help.
Well, both proteins and nucleus acids are both made up of mostly carbon, hydrogen, nitrogen, and oxygen, the elements are assembled in vastly different ways.
A control is the normal behavior you are testing the variable against. There are two types of variables. The independent variable is what you change to test what the dependent variable is, which is the variable that changes due to the independent variable, and what you generally record your data over.