Q: What is the missing first step of the following process: - The oxygen travels into the lungs - The oxygen binds to hemoglobin proteins within erythrocytes (red blood cells) - The erythrocytes are pumped through the body by the heart - All cells receive the oxygen.
A: Oxygen enters the body through the mouth or nose

Q: What is the missing first step of the following process: - Aluminum flows into streams and lakes - Acid rain dissolves minerals and nutrients in soil - Washes them away so plants can't benefit from them - PH in soil and water gets affected which can kill plants and animals - Acid rain in fog at higher elevations can strip foliage off trees.
A: Acid rain leaches aluminum from clay particles in soil

Q: What is the missing first step of the following process: - Engines produce carbon dioxide - Living things produce waste - Waste decomposes - Decomposition produces methane - Water evaporates - Water vapor joins the atmosphere - Carbon dioxide, water vapor and methane are greenhouse gases -
A: People breathe and expel carbon dioxide

Q: What is the missing first step of the following process: - The magma cools - Crystals form and the magma become igneous rocks - The igneous rocks break down into sediment - Become sedimentary rocks - If subjected to heat and/or pressure from plate-tectonic activity the sedimentary rocks become metamorphic rock - The metamorphic rocks melt - Become magma again.
A:
Rock begins as magma from a volcano