input question: What is the missing first step of the following process: - Water is absorbed through roots - Chloroplast cells in leaves contain chlorophyll - Chlorophyll absorbs energy from sunlight - Energy splits water molecules into hydrogen and oxygen - Oxygen gets released into atmosphere - Hydrogen and carbon dioxide used to create glucose - Glucose is food for plants.???
output answer: Carbon dioxide passes through stomata in the leaves

input question: What is the missing first step of the following process: - Over time, more sediment piles on top - The resulting heat and pressure transforms the organic layer into a dark and waxy substance known as kerogen - Left alone, the kerogen molecules eventually crack - The molecules break up into shorter and lighter molecules composed almost solely of carbon and hydrogen atoms - It will turn into either petroleum or natural gas -???
output answer: Dead organic material accumulates on the bottom of oceans, riverbeds or swamps, mixing with mud and sand

input question: What is the missing first step of the following process: - Rain falls - Water is in the area of high elevation - The water creates a stream - The stream moves towards lower elevation - The stream continues along the same path for a long time - The soil and rocks erode where the stream touches them - The stream moves deeper into the soil - The stream is smaller than the eroded area.???
output answer: An area is at a higher elevation than the surrounding area

input question: What is the missing first step of the following process: - Nephrons in the kidney filter the blood - The waste that is filtered out mixes with water - Become urine - Ureters carry urine out of the kidneys.???
output answer:
Blood carried into kidney by the renal artery