Phosphorus is often scarce in soils, so a deficiency in phosphorus may limit plant growth. plants need this essential element because it is a component of what organic molecules? (select all that apply.)

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.