Question

Two groups of tomatoes were grown under laboratory conditions, one with humus added to the soil and one 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 _________.
a. the humus contained minerals such as magnesium and iron, needed for the synthesis of chlorophyll Correctb. the heat released by the decomposing leaves of the humus caused more rapid growth and chlorophyll synthesisc. the humus made the soil more loosely packed, so water penetrated more easily to the rootsd. the healthy plants used the food in the decomposing leaves of the humus for energy to make chlorophyll

Answer 1

Answer:

The correct answer is option a. "the humus contained minerals such as magnesium and iron, needed for the synthesis of chlorophyll".

Explanation:

Plants require magnesium and iron to synthesize chlorophyll. The growing areas of the plants, such as stem, seeds absorb magnesium and use it as magnesium pectate, which gives a ring structure to the chlorophyll. On the other hand, iron is essential to perform photosynthesis, which is the main process that occurs in chlorophyll. A plant without these two minerals, that are in humus, will not be able to have chlorophyll and will have the yellowish color that is described in the question.