I think it is A but not 100% sure. Think of an enzyme like a key unlock the lock is the protein. And to activate getting inside your car or house you have to fit the key into the lock.
        
             
        
        
        
Answer:
hope it's right 
Explanation:
1)Cerebrum: is the largest part of the brain and is composed of right and left hemispheres. It performs higher functions like interpreting touch, vision and hearing, as well as speech, reasoning, emotions, learning, and fine control of movement. 
2)Cerebellum: is located under the cerebrum. The cerebellum receives information from the sensory systems, the spinal cord, and other parts of the brain and then regulates motor movements. The cerebellum coordinates voluntary movements such as posture, balance, coordination, and speech, resulting in smooth and balanced muscular activity.
 
        
             
        
        
        
The common ancestor.
A phylogenetic tree shows how a species
originates (by evolution) other species. It’s very similar a genealogic tree. If
you want your family tree, you should write down your name and the names of all
your brothers and sisters and then draw a line from all those names to the
names of your parents, and then draw a line from the name of your father to the
names of your gramma and grampa, and then do the same with the names of your aunts
and uncles. If you repeat the process with many, many generations, you will
have the common ancestor to all of those relatives. You can do the same with
species: for example, humans are supposed to have a common ancestor with
monkeys, so their lines will end together in the same point in the graph. Then
you have to draw a line from that point to another point that will be shared
with other mammalians, then Mammalians share a point with other vertebrates,
and so on… If you keep on going, you will get to LUCA someday.
 
        
             
        
        
        
The simple answer is that in a battery the chemical reactions that produce the electrical current are produced from materials that are already in the battery itself, whereas in a fuel cell, the reactants, almost always Hydrogen and Oxygen are fed to the cell like an external fuel.
. However, while a battery makes electricity from the energy it has stored inside the battery, a fuel cell makes its electricity from fuel in an external fuel tank This means that while a battery may run dead, a fuel cell will make electricity as long as fuel is supplied. For hydrogen fuel cells, hydrogen is the fuel and it's stored in a tank connected to the fuel cell. When hydrogen in the tank runs low, you refill it, or replace it with a full tank.  
 
        
             
        
        
        
Answer:
The nucleus in a cell is like a brain in a human. It is the power house. The nucleus tells everything in the cell what to do and when to do it.
Explanation: