Pre-Lab Assignment 1. In a demonstration of Agar cube cellular transport, a stu-

Question

Pre-Lab Assignment 1. In a demonstration of Agar cube cellular transport, a stu- dent prepared blocks of gelatin to simulate cells and a container filled with blue dye (the dye was to simulate an es- sential nutrient that will enter the cells). Three of Blue dye the blocks were cubes, with one cube measur- ing 0.5 cm on each side, one measuring 1 cm on each side, and the third one measuring 2 cm on each side. The fourth block was a slab measuring 4 cm by 4 cm by 0.5 cm. The blocks were submerged into the blue dye for one hour at a side counter in the lab room. After that hour, the blocks were removed and cut in cross section so that the depth to which the dye penetrated the blocks could be measured After one hour Demonstration setup The chart that follows shows some of the measurements and calculations of dye pen- etration into the blocks. Complete the chart by calculating the missing mea- surements

Explanation / Answer

1.

Surface area to volume ratio :

1cm, 6:1

2cm, 3:1

4X4X0.5cm, 5:1

Since it is a 3D object the dye will penetrate from all sides hence we subtract xcm (length of dyed area) twice from all length. Therefore 1cm cube becomes 0.8 cm cube.

2. Dye penetrated by diffusion process in the gelatin blocks.

3. Length wise penetration of dye was same in all objects but volume wise it was maximum % volume of block dyed is for 0.5cm cube.

4. In refrigerator the dye will start to freeze and hence the size of dye molecules increases which reduces the rate of diffusion. Less volume of the blocks would be dyed.

5. We can know about osmosis of water molecules by finding the concentration of cell and the environment. In a hypotonic environment water will enter the cells of Elodea and hence the cytoplasmic volume increases.

6. In a hypertonic solution the concentration of solute is more in the environment, like in this case 10%NaCl is present in the solution in which red blood cells are present. Here the water will flow out of RBCs to the environment until the osmotic pressure is equal in and out side of the cell. Cytoplasmic volume of RBCs will reduce.

1CM    2CM 4X4X0.5 CM LENGTH OF DYE FREE AREA 0.8 1.8 3.8X0.3 VOLUME OF DYE FREE AREA 0.512 5.832 4.332 VOLUME OF DYED AREA 0.488 2.168 3.668 % VOLUME DYED 48.8% 27.1% 45.85%

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