Cells need to intake things like nutrients, water, and oxygen, and they need to be able to export things like metabolic products and waste materials. No matter which direction the material is moving in, it needs to cross the cell membrane at some point.
Answer: Chemical energy is energy stored in the structure of molecules within the bonds between atoms. Energy can be added or released from a molecule by changing the arrangement of electrons (rearranging chemical bonds).
Explanation:
Natural selection. The trait that is unfavorable to the baby giraffe's survival will cause the death of giraffes with that specific gene that is responsible for a short neck vs a long neck. Natural selection causes traits that help the survival of the species will be carried throughout generations while unfavorable traits will be lost.