It 'expires.' The leaf becomes brown and dry within a weak thin layer called the 'terhomos.' This is the part of the leaf collects sun energy. As the leaf is in the plastic bag, the sun energy will not be able to be received by the leaf.
The air will become humid and warm. The water lost from the stomata by transpiration will be trapped in the bag. I'm not certain as to how the air become warm, but I am sure that it does.
It gets stretched.
it wouldn't make any affect, we think, and it would just stick to the plastic bag!
the plastic bag will get get stuck in its oesophagus and if its large enough to choke the cow it will leave the planet.
It will mold!
It will keep insects away. Many people put plastic bags around their fruit, still on the tree, to guard against fruit fly, parrots, other birds and flying foxes (fruit bats).
you stop breathing.
sets on fire
The branch will die.
in the plastic bag first
plastic bag
the plastic bag will become foggy and will act like condensation. the water will turn into ice and when you take it out of the freezer, you can rub away the "fog" with your finger :)