(c)Why was no starch found in:(i)the part of the leaf labelled A................................................................
......................................................................................................................................................................................(1)(ii)the part of the leaf labelled B?......................................................................................................................................................................................................................................................(1)(Total 7 marks)Q3.A plant with variegated (two-coloured) leaves was left in sunlight for several hours. Pieces of one of its leaves were then detached (removed) and tested for sugar. The diagram below shows the results.Explain, as fully as you can, why the yellow region of the leaf had not produced sugar
During photosynthesis a plant absorbs light energy using the pigment chlorophyll. This allows it to convert carbon dioxide and water into glucose. This glucose is:
transported to the growing parts of the plant for use in respiration
transformed into cellulose, proteins and oils
turned into starch for storage
Therefore, to test if a plant has been photosynthesising, you can test the leaf to see if starch is present.
The solution is hypertonic because the amount of solute(s) is higher outside of the cell than it is inside the cell, so the solvent (e.g. water) would move from the cell to the solution in order to obtain equilibrium between the two.
Explanation: In gel electrophoresis, the smaller the size/molecular weight of DNA the faster it moves across the gel and vise versa. This is as a result of the pore size of the gel which is usually prepared 1g of agarose in 100ml of distilled water. So a DNA fragment with 1000 base pairs will "struggle" its movement across the gel pore making it mive less faster and further. Movement and molecular weight of DNA are inversely proportional.
