What two forms of nitrogen can plants absorb?

Plants primarily absorb nitrogen in two inorganic forms: ammonium (NH4+) and nitrate (NO3-). Ammonium is a positively charged ion, and when present in the soil, it can be directly taken up by plant roots and utilized in amino acid synthesis and other metabolic processes. Nitrate, on the other hand, is a negatively charged ion that is also soluble in water, making it easily available for uptake by plants.

The ability of plants to absorb these two forms is crucial for their growth, as nitrogen is essential for the formation of proteins and nucleic acids. This is why the selection highlighting ammonium and nitrate as the absorbable forms of nitrogen is accurate. In contrast, other options either include forms that are not easily absorbed by plants or are not bioavailable in a form that plants can use directly.