Health and safety assessment table: Equipment:
Background: A cereal grain contains a store of starch within the endosperm. During germination the starch must be made soluble so that it can be transported to the embryo to support the growth of the seedling. The embryo is much smaller than the endosperm and is situated at the more pointed end of the grain. The developing embryo releases gibberellins that act on a layer of cells on the outside of the endosperm, stimulating these cells to release the starch-digesting enzyme amylase. "Gibberellic acid does not merely trigger α-amylase synthesis, but it is continuously required during the period of enzyme formation" (1). In this activity you will remove the embryo and investigate the effect of different concentrations of gibberellin on the production of amylase. The production of amylase will be assessed by using a starch agar assay. Cereal grains that have had the embryo removed are first soaked in gibberellic acid, then placed onto the starch agar plates and incubated. The agar plate is then flooded with iodine solution, which stains starch blue-black. The areas where starch has been digested will not stain. The size of the clear area around a cereal grain indicates the amount of amylase produced by the seed. Variables: Independent variable:- Concentration of the Gibberellic acid Dependent variable:- Size of the zone of exclusion. This will be attained placing the zone over a sheet split up into 1mm by 1mm squares and counting the squares that fit into the zone to work out the area in mm^2 Controlled variables:-
1 Comment
Mr Lovat
5/5/2017 02:01:15 pm
Great risk assessment (3a), consideration of variables (2c) and good use of a relevant peer reviewed journal article to support your conclusion (5b). Well done, Jack.
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March 2017
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