Homeostasis in plants — practice question

The grass Oryza sativa is cultivated as a food crop for rice production. Rice plants are adapted to live with their roots submerged in water. An experiment was done to study the formation of aerenchyma tissue in the roots of rice plants. - 10-day old seedlings were grown with their roots submerged in water. - Some were grown in water that was kept oxygenated, while others were grown in water that had no oxygen (deoxygenated). - At 12 hour intervals, some seedlings from each group were taken out and transverse sections of their roots were prepared and examined. - The sections were cut at the same distances from the root tip to assess development. - The percentage of root tissue that had developed into aerenchyma tissue was calculated. The results are shown in Fig. 7.1.