Question

Lab Exercise 3A Discuss why you think cells would evolve to have a certain shape. Think about tf cells that you looked at earlier with shapes other than a sphere or cube. How doy think a shape other than spherical or cuboidal could help speed up difusion acros 2) the plasma membrane? OSMOSIS ANI QUESTION: CAN THE TONICITY DETERMINED EXPERIMENTALL 3) Mature red blood cells (RBCs) do not have a nucleus, which changes its shape from spherica OBJECTIVES I to a donut-like shape. Explain how the loss of the nucleus in a mature BC would affect its surface area to volume ratio and how you think this would be important for diffusion of ox ygen that occurs into and out of the RBC. L. formulate a scientific hypo 2. design and understand a b 3. distinguish between depe 4. measure the mass of an o 5. calculate volumes needex 6. express data in tabular f rate. 7. determine the tonicity ( 8. explain the importance 4) To calculate a rate, divide the change in the amount of something (e.g. mass or distance) by the change in time Change in amount Change in time Every scientist approaches a worked on. After observing follows 3.5mm Calculate the rate of diffusion for each cube in table 2, using the avara How far does the acid diffuse?] ge time. [Hint Observation: Observe in the natural world Rate of Diffusion in Cubes of Different Size Side Length of Distance Acid Average Time of Rate of Diftus Diffused (mm) Diffusion (min Cube (mm) Question: Ask a ques how it works mm/min 3.5 10 20 Harris, Dr. Katherin http://www.hartnelle 72

Answer 1

Hi
1) The diffusion of particles across plasma membrane depends on several factors. One of the key factor is cell shape. The cell shape determines the surface to volume ratio. So different shapes can actually increase the surface area in comparison to the volume of the cells; this causes the surfacr area to volume ratio to increase. This speeds up the rate of diffusion.

2) The RBC carry oxygen to tissues. They loose their nucleus during maturation. This allowed the cells to take biconcave shape which has more surface area compared to volume. The RBC has hemoglobin which is attached to its surface. More surface area means more hemoglobin and better oxygen carrying capacity.

4) To solve this question, the size of cube in table 2 is needed. If you have it in the book, just divide the distance the acid traveled by the time it took.