Germinating Barley Lab Report

Practical 3 report[pic 1]

The assessment for practical 3 is a written report in the format of extended answer questions. There are 3 questions in this report and each student should answer all 3 questions.

Answers are expected to conform to the scientific writing guidelines on the Moodle page, including all citations (in-text and reference list) to be in the CSIRO referencing format.

Guidelines on word count, submission, and getting-started hints can be found in the ‘Practical 3 Assessment Overview and Instructions’ document on Moodle. Students should ensure they read this document before beginning their report.

1. You have performed an experiment (your practical 3, Metabolism experiment). You wish to tell your scientist friend about this experiment so they can replicate it exactly. Write a methods section for this practical.

Prepare the amylase extract from the germinating barley by patting dry 10 germinating barley seeds, weighing them and then crushing them to form a fine paste. Add 10mL of buffer solution and continue to crush so amylase extracts into the solution. When the solution becomes clouded, filter it through a tea strainer into a 100mL beaker, then record the volume in a measuring cylinder and return it to the beaker. Dilute the amylase extract by adding 20mL of buffer into a measuring cylinder and then adding 5mL of amylase extract, ensure to mix well. Create a control by adding 5mL of diluted amylase extract to a test tube and put it in boiling water for 10 minutes. After 10 minutes, leave it to cool at room temperature.

Determine the amylase activity in germinating barley by measuring the rate of starch hydrolysis. To do this, place one drop of iodine into each of the twenty-one wells on the ceramic plates, then prepare a solution of 5mL of buffer and 1mL of 0.5% starch solution in a test tube to create the ‘reaction mixture’. Add a single drop of the ‘reaction mixture’ to a drop of the iodine in the well labelled ‘T’; it should turn to a blue/black colour, indicating the presence of starch in the reaction mixture. Remix the diluted amylase solution well and then add 1mL of diluted amylase extract to the reaction mixture in the test tube at t=0 and mix well; this is the amylase reaction mixture. Add a drop of the amylase reaction mixture to the wells at one-minute intervals, starting with number zero, until the achromic point is reached. Once the achromic point has been reached, save the amylase reaction mixture for determining maltose later on. Repeat the experiment using identical volumes of buffer and starch that gave a satisfactory reaction rate in the previous step, but replace the diluted amylase extract with the same volume of boiled control extract. The use of a boiled control will demonstrate how