The Figure Below Shows the Results of a Study to Determine

question 55

Multiple Choice

The figure below shows the results of a study to determine the effect of soil air spaces on plant growth.

-The best explanation for the shape of the growth response curve in the above figure is that

• A)the plant requires air in the soil for photosynthesis.
• B)the roots are able to absorb more nitrogen (N₂)in high levels of air.
• C)most of the decrease in weight at low air levels is due to transpiration from the leaves.
• D)increased soil air produces more root mass in the soil but does not affect the top stems and leaves.
• E)the roots require oxygen for respiration and growth.