
<h2>Fixation</h2>
Nitrogen in its gaseous form (N2) can’t be used by most living things. It has to be converted or ‘fixed’ to a more usable form through a process called fixation. There are three ways nitrogen can be fixed to be useful for living things:
<h3>Biologically: </h3>
Nitrogen gas (N2) diffuses into the soil from the atmosphere, and species of bacteria convert this nitrogen to ammonium ions (NH4+), which can be used by plants. Legumes (such as clover and lupins) are often grown by farmers because they have nodules on their roots that contain nitrogen-fixing bacteria.
<h3>Through lightning: </h3>
Lightning converts atmospheric nitrogen into ammonia and nitrate (NO3) that enter soil with rainfall.

Answer:
The youngest crust (shown in red) is near mid ocean ridges and spreading zones. All three rock types in the earth's crust—igneous, sedimentary, and metamorphic—can also be recycled back to their original molten magma form. This process occurs when oceanic crust is pushed back into the mantle at subduction zones.
Answer: A
Explanation:
The central dogma of biology is that dna makes rna which makes protein
Compare: They both are products of DNA. They both are equally important to a living organism. Contrast: Genotype is the genetic makeup, while Phenotype is the physical appearance. Genotype can't be seen but phenotype can.