Primary plant/tree growth is characterized mainly by primary plant/tree growth is characterized mainly by seed germination growth and production of wood development of leaves which are essential to photosynthesis upward and downward growth due to cell division at tips of roots and shoots change in diameter of the stem/trunk

Primary plant/tree growth is characterized mainly by .

upward and downward growth due to cell division at tips of roots and shoots

Explanation:

Plants are organisms that have different parts constituting their bodies, as well as animals do. Therefore their growth is considered in the same way animal growth is considered. Taking as the first element the cell division from roots to shoots. This is a very important clarification because we consider wrongly sometimes that roots and shoots are not part of the actual plant when they are.

oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%

layer 3 is younger than layer 6.