Problem: What is the missing first step of the following process: - Water is transported to the leaves in the xylem - Energy harvested through light reaction is stored by forming ATP - Carbon dioxide and energy from ATP are used to create sugar - Oxygen exits the leaves through the stomata by diffusion - The plant reuses the water or the water exits through the stomata as water vapor.

A: Carbon dioxide enters the leaves through the stomates by diffusion

Problem: 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 -

A: Dead organic material accumulates on the bottom of oceans, riverbeds or swamps, mixing with mud and sand

Problem: What is the missing first step of the following process: - The items are sorted - Trash is removed from everything else - Goes to a landfill - The items go into a baler machine for each kind of material - They come out as bales - The bales are shipped to manufacturers to use to make products.

A: Items are collected

Problem: What is the missing first step of the following process: - Carbon dioxide from the burning fossil fuels enter the atmosphere - The make-up of the atmosphere changes - Some energy from the sun cannot escape back through the changed atmosphere - The earth begins to heat because of the extra trapped energy - Human beings cut down trees - Human beings do not re-plant the trees - Trees cannot help take the extra carbon dioxide from the atmosphere - The extra trapped energy starts to change the earth's short term weather - Eventually the long-term climate patterns start to change -

A:
Human beings burn fossil fuels (oil, gas, etc.)