Nitrogen.
Plants cannot use atmospheric nitrogen directly. Nitrogen from the air must be converted into the different form so plants can absorb it. Thus plants need nitrogen-fixing bacteria to convert atmospheric nitrogen into ammonium, which is available for plants to absorb it.
The driving force of photosynthesis is the energy that is contained in sunlight. This energy is transformed to energy that plants and other organisms use to live.
The most important factor that limits the size of a cell is the ability of the cell to transport materials efficiently into and out of the cell. In this case the size of a cell should have a particular form in order to export and import material.
In general cells that need more energy, since mithocondria are responsible for making and processing ATP.
Common examples of cells with many mithocondria are muscle cells that are in current activity all the time, specially heart muscles and muslces in the respiratory system such as the diafragma since the heart beats all the time, non-stop, that is, unless you die of course and so do the muslces needed to breath.
Hope it helped,
BioTeacher101
They are further down because of superposition and faunal succession
