Two groups of tomatoes were grown in the laboratory, one with humus added to the soil and the other a control without humus. The leaves of the plants grown without humus were yellowish (less green) compared with those of the plants grown in humus-enriched soil. The best explanation for this difference is that .

The best explanation for this difference is that the humus contained micronutrients needed by the plants for the synthesis of chlorophyll, such as Manganese (Mn), Iron (Fe) and Copper (Cu).

Explanation:

Chlorosis is the yellowing of plant leaves, and this is due to the deficiency in the amount of chlorophyll contained in the plant leaves. Iron (Fe) is an essential micronutrient for the synthesis of chlorophyll, which is an enzyme-catalyzed reaction. Copper (Cu) is a component of most enzymes, while Manganese (Mn) is a cofactor, required for the activation of the enzymes that catalyze chlorophyll synthesis, hence deficiency of these nutrients will result in the development of chlorosis.

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.