Answer : Hydrogen.......:
Plant cells have what is perhaps the most complex outer coverings. Plant cell walls are made largely of cellulose which forms strong, highly rigid, almost indigestible coverings that protect the cell and gives it shape.
The Miller-Urey experiment showed that simple molecules could have arisen abiotically. This chemical experiment included conditions similar to those present on the early Earth, and tested the origin of life under those conditions.
Water (H2O), methane (CH4), ammonia (NH3) and hydrogen (H2) were the chemicals used to produce the results of the experiment, the factors needed for simple life to arise. Given similar conditions on other planets, it's possible that life could arise there as well.
Answer: true
Explanation: the upper part (scion) of one plant grows on the root system (rootstock) of another plant. In the budding process, a bud is taken from one plant and grown on another.
