Correct answer: D) From bacteria living in their roots
Nitrogen is an essential plant nutrients, but it is metabolically unavailable to higher plants and animals. It is available to some species of microorganism by biological nitrogen fixation in which nitrogen is converted to ammonia with the help of enzyme dinitrogenase.
The process of breaking apart the two atoms in a nitrogen molecule is called nitrogen fixation. Plant obtain the nitrogen they need from the soil which is already fixed by the bacteria and archae.
Example: <em>Azobacter</em><em>,</em> Nostac
Reinforcement and support
parenchyma, in plants, tissue typically composed of living cells that are thin-walled, unspecialized in structure, and therefore adaptable, with differentiation, to various functions. The cells are found in many places throughout plant bodies and, given that they are alive, are actively involved in photosynthesis, secretion, food storage, and other activities of plant life. Parenchyma is one of the three main types of ground, or fundamental, tissue in plants, together with sclerenchyma (dead support tissues with thick walls) and collenchyma (living support tissues with irregular walls).
Russia has the largest natural gas reserve. The United States has the 6th largest natural gas reserve. Saudi Arabia or Venezuela may have the largest oil reserves.
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Difficulties will occur to every one, with respect to this theory." Darwin's contemporaries were eight characters, Alfred Russel Wallace, Charles Lyell, Ernst Haeckel, Gregor Mendel, Mary Anning, Robert Chambers, Thomas Henry Huxley and Thomas Malthus, and the two potential difficulties that might have troubled darwin's contemporaries were the lack of transitional forms and insufficient time for different forms to evolve.