Answer to Question #103484 in Biology for Elie

Question

Plant Growth Substances stimulate root growth from a cut stem.
Describe an investigation to find the best concentration of plant growth substance to simulate root growth.
You should include experimental details in your answer and write in full sentences. (6 Marks)
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Answer 1

The experiment is based on the estimation of the length of the roots formed on the basil stem placed in water containing a certain concentration of the substance stimulating root growth. For the procedure, ten two-fold dilutions of the substance must be prepared. More specifically, put 20 ml of water into ten glasses. Then, add 20 ml of the substance into the first glass, mix it, take 20 ml of the solution and add it to the second glass. Repeat the procedure with the rest glasses and remove 20 ml of the solution from the last one. Add one more glass containing 20 ml of water. Label all the glasses with appropriate names. Cut eleven similar basil stems with leaves. These stems must be cut with a sharp knife. Put the basil stems into the labelled glasses and place them near the source of light. Measure the length of roots formed on the stem. The longest root will indicate the most efficient concentration of the substance.