Food chains and webs not only describe the order organisms are eaten, but they also describe the flow of energy in an ecosystem. We and all things are made of energy, so the way that energy change forms and pass from one thing to another is one way to describe an ecosystem, and more in general it is a correct way to explain how life on Earth works.
Answer: 3. Atomic number
Explanation: Good luck! :D
What's the ? s you need help on
Oligonucleotide primers associate by hydrogen bonding to specific sections; primers are then extended.