Answer:
cell membrane
Explanation:
the cell membrane protects the cell from going anywhere or anything coming inside
I think that the best phrase to fit into the blank is a "scientific theory".
A scientific theory is developed through experiments which use the scientific method, and a theory can be improved if additional data is available or if people provide suggestions which make the theory fit the data better.
One of the challenges that scientists face when classifying a new fossil is that any tiny detail is all that separates one species from another. Further exploration is required to identify another set of characteristics that may help in deciding which organism belongs or create a new class.
Answer:
hydrogen bond
Explanation:
The slight positive charges on the hydrogen atoms in a water molecule attract the slight negative charges on the oxygen atoms of other water molecules. This tiny force of attraction is called a hydrogen bond. This bond is very weak.