You take a large sample of soil and divide it among individual pots. You then separate the pots into two groups. In the first group, every pot of soil has been sterilized. In the second group, none of the pots of soil have been sterilized. You plant soybean seeds in all the pots. What would you expect to see as the seeds sprout and grow?
A) The plants growing in the sterile soil are bigger because they have not been exposed to any bacteria.
B) The plants growing in the non-sterile soil are bigger because they have mutualistic associations with nitrogen-fixing bacteria.
C) The plants growing in the sterile soil are bigger because they do not have to compete with nitrogen-fixing bacteria in order to obtain usable nitrogen.
D) The plants growing in the non-sterile soil are bigger because saprotrophic bacteria produce nutrients for them.
E) There is no difference in size between the plants growing in the sterile soil and those in the non-sterile soil.

Question

Quizplus · Accepted Answer

Soybeans form mutualistic associations with nitrogen-fixing bacteria, which help the plants by converting atmospheric nitrogen into a form that the plants can use. This typically results in better growth and development for plants in non-sterile soil compared to those in sterile soil, which lack these beneficial bacteria.

You Take a Large Sample of Soil and Divide It