Two groups oftomatoes were grown under laboratory

Chapter 0, Problem 6

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Two groups oftomatoes were grown under laboratory conditions, one with humus added to the soil and one a control without humus. The leaves ofthe plants grown without humus were yellowish (less green) compared with those ofthe plants grown in humus-enriched soil. The best explanation for this difference is that a. the healthy plants used the food in the decomposing leaves ofthe humus for energy to make chlorophyll. b. the humus made the soil more loosely packed, so water penetrated more easily to the roots. c. the humus contained minerals such as magnesium and iron, needed for the synthesis of chlorophyll. d. the heat released by the decomposing leaves of the humus caused more rapid growth and chlorophyll synthesis. e. the healthy plants absorbed chlorophyll from the humus.