Question

MICROSCOPE in the bles, anwwer the questions and and upload you simeton Wackboard total magnification - hjective Raquel August about the cb ctures. Use the ve lens is in Thinking about Diffusion and Cell Shapes tipe color of lective lens id low 1) Why do you think cells would evolve to have a certain size? How does cell size help speed up or slow down diffusion across the plasma membrane and through the cytoplasm of a cell? Cell evolve to a certain sizeye to Surface area to volune. if the cell gets bigger, there be less Suface area with compared 2) Why do you think cells would evolve to have a certain shape? Think about the cells that you looked at earlier with shapes other than a sphere or cube. How do you think a shape other than spherical or cuboidal could help speed up diffusion across the plasma membrane? rek mag 3) Mature red blood cells (RBCs) do not have a nucleus, which changes its shape from spherical to a donut-like shape. Explain how the loss of the nucleus in a mature RBC would affect its surface area to volume ratio and how you think this would be important for diffusion of oxygen that occurs into and out of the RBC. 4) To calculate a rate, divide the change in the amount of something (e.g. mass or distance) by the change in time: 7mm Change in amount 7 mm Rate = Change in time 3.5 mm Calculate the rate of diffusion for each cube in Table 2, using the average time. (Hint: How far does the acid diffuse?] Rate of Diffusion in Cubes of Different Size Side Length of Distance Acid Average Time of Rate of Diffusion Cube (mm) Diffused (mm) Diffusion (min) (mm/min) 7 3.5 10 15 20

Answer 1

1. Size of the cell is always kept smaller inorder for the surface are to volume ratio to be higher. More surface area will allow more materials to enter cell easily.

2. Cells are of different shapes. Shape is dependent on the function a cell performs. The shape is also important for diffusion of materials. This is because,cell those line the intestine have to absorb materials from the small intestine in to the blood. These cells have what is called the microvilli which increases the surface area of the cell much higher for faster absorption of the materials.Cells lining the kidney tubules are very thin and flat, which also allows more ansorption of the materials.

3. Removal of the nucleus in RBCs gives them a flat biconcave structure. Such a biconcaves structure again gives more surface area than spherical or flat RBCs. So the surface area to volume ratio is higher in biconcave RBC. More is the surface ,area, more is the absorption of O2.