Problem: -  Air goes through all the little branches in your lungs to fill up the air sacs, or alveoli - Oxygen goes through the walls of the alveoli and into the capillaries - The oxygen goes into the bloodstream - Oxygen is left and carbon dioxide is picked up - You breathe it out through your lungs -   What might be the first step of the process?

A: You breathe in


Problem: -  Once in the lungs, oxygen is moved into the bloodstream and carried through your body - At each cell in your body, oxygen is exchanged for a waste gas called carbon dioxide - Your bloodstream then carries this waste gas back to the lungs where it is removed from the blood stream and then exhaled - Your lungs and respiratory system automatically perform this vital process, called gas exchange -   What might be the first step of the process?

A: He air we breathe contains oxygen and other gases


Problem: -  Embryo is C - Embryo grows and develops into a fetus inside the woman&#x27;s womb - The fetus is born - Begins to grow and develop through infancy and childhood - In the teenage years the human experiences puberty - Reaches sexual maturity - At 18 the human becomes an adult - Adult may procreate continuing the cycle.  What might be the first step of the process?

A: A man and woman mate


Problem: -  Sunlight is gathered by the leaves of the plant - The sunlight is broken down into glucose through photosynthesis - The glucose travels the plant - The plant uses that glucose as energy to grow.  What might be the first step of the process?

A: