The property of soil that is least conducive to plant growth would be:
1. a large percent of humus content
2. a large number of soil organisms
3. a compacted soil
4. a soil with high porosity

The uptake of which of the following by a plant contributes maximum to its dry weight:
1. water and minerals through root hairs.
2. water and minerals through mycorrhizae.
3. carbon dioxide by leaves through stoma.
4. sugars in the root hairs.

What percentage of the dry weight of a plant is made up of organic molecules?
1. 10%
2. 23%
3. 72%
4. 96%