Compare the rate of utilisation of food reserves during the germination of seeds of the two following species/types: Monocotyledons, and Dicotyledons.

A typical dicot follows near enough the same process. One difference I found was the fact that monocots store starch in endosperms, and only break it down, or use it, as they need it. In comparison to this dicots store starch in cotyledons, and the endosperm is reduced to a papery coating around the embryo.

How does amylase break down starch?

Amylase, like other enzymes, works as a catalyst, i.e. it is unchanged by the reaction, but makes the reaction easier by reducing the energy required for it to happen. Catalysts speed up the reaction. The theory behind the working is called the "lock and key" theory: the enzyme is shaped so that the products fit into them, react and are released. Amylase digests starch by catalysing hydrolysis, which is splitting by the addition of a water molecule. Therefore starch plus water becomes maltose (which is equivalent to two joined glucose molecules).

Factors affecting Germination:

There are a number of environmental factors, which affect the germination process:

Preliminary Tests:

Apparatus:

Method:

• Start with 750 pea seeds (dicotyledon) and 750 wheat seeds (monocotyledon).
• Use the following procedure for both types of seeds:

1. Split the seeds up into groups of 25. (Fewer than 25 with not show up well on the scales, as they would be too light). This means you would have 30 groups of seeds.
2. Then separately take each group of seeds, and using electronic scales, weigh the group of seeds, and record in the table given below (Table 1)
3. Then place the group of seeds in a beaker, which has been half filled with ordinary tap water. And label it so that it matches the table, i.e. as below. (Repeat this with each group of seeds)

4. These must then be left over night (for 24 hours), so that the seeds can absorb the water and the first stage of germination can commence.
5. Then place the group of seeds in a seed tray, which have been filled with cotton wool that has been soaked in water.
6. Label the dish so that it matches the table, and therefore the beaker they have just come from.

Repeat this procedure with each group of seeds so that you have 30 seed trays filled with 25 seeds.

7. The seed trays should be stored in a light place, for example on a windowsill, but they must all be stored together so that they are under the influence of the same conditions.
8.  The next day (known as Day 1 in the table), take the 3 seed trays labelled Day 1.
9. Then place the groups of seeds on separate pieces of paper towels (making sure that you label which set of seeds is from which test) which can then be placed in a drying cupboard. Leave the peas in the cupboard for around 2 ½ hours and the wheat for around 1 hour. Any longer than this and the seeds begin to burn.
10. Then take each group of seeds out, and weigh them, using the same set of electronic scales that were used previously. (You can either take the seeds off the towel and weight them separately, or weigh them with the paper towel. Then weigh the paper towel separately and subtract the difference)
11. Record the weights in the table (table 1), and work out the calculations.
12. On the second day repeat this procedure using the peas labelled day 2 tests. Record the results in the table.
13. Follow this procedure everyday for the various groups of seeds and record everything in the table.
14. When all results have been obtained, fill in table 2, and then using this info plot a graph of comparison (see graph 1).

Variables:

        The variable being tested/changed is the number of days the seeds are being germinated for. There are a number of things that must be kept constant and not changed for the test to be fair. These include:

• Drying Time
• Factors/conditions for germination including temperature, light, water, oxygen.
• Make sure both seed types are left germinating for the same amount of time.
• Use the same set of scales for weighing the seeds.

Prediction:        

From my previous knowledge and research I can make 3 predictions as to what will happen:

 

Results Table:

Table 1

Table 2

Graphs:

The following graphs should be used to plot the results on so that a comparison can be made between the various results obtained from the different types:

Graph 1

Sources/References:

University of Bath Science 16-19-Biology, Martin Rowland, 1992

 

Biology 2, Mary Jones, Jennifer Gregory, Cambridge, 2001

Biological Science, Green, Stout, Taylor, 2nd Edition, Cambridge, 1991