A student investigated the effects of indoleacetic acid (IAA) on the growth of oat seedlings (young plants). The student: • removed the shoot tip from each seedling and cut out a 10 mm length of shoot...

Explain why the student added glucose solution to each Petri dish.


Extracted text: A student investigated the effects of indoleacetic acid (IAA) on the growth of oat seedlings (young plants). The student: • removed the shoot tip from each seedling and cut out a 10 mm length of shoot • placed 10 lengths of shoot into each of 5 Petri dishes • added to each Petri dish an identical volume of 5% glucose solution • added to each Petri dish 40 cm of a different concentration of IAA solution • left the Petri dishes at 20 °C in the dark with their lids on for 5 days • removed the shoots after 5 days and measured them • determined the mean change in length of shoot at each concentration of IAA. Table 1 shows her results. Table 1 IAA concentration added to Petri dish 10 5 10 3 10 1 1 10 / parts per million Mean change in length of shoot / mm 0.0 0.1 1.3 2.4 3.1