Plants grow in many different shapes and sizes. Much of their shape depends on an internal structure that is composed of carbon-containing molecules such as cellulose and lignin. Plants that have a strong internal structure can grow larger than other plants because their structure can support their size.

Plants obtain the majority of the carbon necessary for building these structural molecules from —

A) air

B) microorganisms

C) soil

D) water

A. Air

Explanation:

Lignin which has a glucos link is a unique hydrocarbon comprising 8-20% of the cell wall of plants. It is a complex, dense, amorphous, secondary cell wall polymer found in the trachea elements and sclerenchyma of terrestrial plants.

Since plant absorbs carbon dioxide from air to form glucose and hence, starch; That is the source of carbon to build other macromolecules.

Water which it absorbs from soil is not of carbon content neither do plant take in microorganisms.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.