CORE PRACTICAL 5 Flashcards
What is core practical 5? (1)
investigate the effect of temperature on beetroot membrane permeability.
what is the pigment in beetroot? (1)
the cells of the beetroot contain an intensely red water-soluble pigment called beta lain in their interior.
in what situation does this pigment leak out of the cell? (1)
this occurs if harmful external conditions are applied to beetroot tissue.
what effect does temperature have on this pigment? (3)
one effect of heat is to denature proteins, and this applies to the proteins of membranes as well as those elsewhere in the cell. one membrane proteins have been denatured, the integrity of the lipid bilayer of the cell surface membrane may also be compromised. escape of the vacuole contents will indicate this has happened.
what is the first step of this practical? (1)
prepare washed beetroot tissue cylinders around 3cm in length and 0.5cm in diameter. cut 10 cylinders.
what is the second step of this practical? (2)
submerge one cylinder in a water bath at 70 degrees for 1 minute. withdraw it and place it in 15cm3 of distilled water in a test tube at room temperature for 15 minutes. remove the tissue cylinder and discard it.
what is the third step of this practical? (2)
cool the water bath to 65 degrees and repeat thee process with the second cylinder, heat treat it and allow it to stand for 15 minutes in distilled water at room temperature, then discard it.
what is the fourth step of this practical? (1)
repeat, using heat treatments decreasing the temperature of the water bath by 5 degrees each time.
what is the fifth step of this practical? (3)
the distilled water in the test tubes becomes coloured by any pigment as a result of the heat treatment. you can measure the pigment using a colorimeter containing a complementary colour filter (a blue filter) set the scale to 0.
