Diffusion and osmosis spurthis ap biology notebook. The purpose of adding phenolphtalein was to make the gel pink. Diffusion is one result of this molecular movement. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Another purpose of this lab is to help describe the effects of water gain and lose in different cells, specifically animal and plant cells. Osmosis and diffusion are two of the most important processes in the study of how organisms maintain homeostasis, particularly with regard to their electrolyte and water balances. Click the yellow make a graph button to visualize your data.
This is the first part of the lab that my group worked on. Substances are routinely transported received and delivered across the cell. Why was it necessary to keep the potato tuber cores in a covered container until the balance was available. Students use models to simulate the movement of water and nutrients across a cell membrane. The movement of a solute through a semi permeable memb rane is called dialysis as well as diffusion. We were testing if diffusion were to occur what would happen.
This ap lab attempts to demonstrate the process of osmosis using dialysis bags. Depending upon the size, molecules would either get inside the bag or rebound back to their original position. Read the introductory information handed out in class and the procedures and answer the following. This movement of molecules from a higher concentration to a lower concentration of a substance is known as diffusion, which is one of the main. During plasmolysis the cell membrane pulls away from. Please print out a copy of the rubric, however, as you will need to turn it in with your lab report in order to get a grade. The diffusion of water molecules across the cell membrane is called osmosis. If you are not familiar with these concepts, make sure that you have looked them up in your textbook. Diffusion and osmosis the cell membrane plays the dual roles of protecting the living cell by acting as a barrier to the outside world, yet at the same time it must allow the passage of food and waste products into and out of the cell for metabolism to proceed. Diffusion is the movement of particles from an area of high concentration to low concentration. These suggestions are provided to enhance the students overall lab experience as well as their conceptual understanding. In this lab, we will be conducting an experiment where we will observe the acts of passive transport. If you had left them out in the open, how might that have affected you results. He then explains the concepts behind the osmosis lab and how potatoes are affected by increasing sucrose molarity.
Also, use the rubric to your advantage when completing your lab, it is a guideline of exactly what youre required to have. You will also learn how to calculate water potential. Ap biology lab 1osmosis and diffusion introduction finding isotonic egg membrane inquiry finding isotonic scale your design ok so in this part its your turn. The three possible cases are that the solutions in the experiment are hypertonic, hypotonic, or isotonic. Diffusion and osmosis laboratory 1, ap biology 2011 spurthi tarugu, kavinmozhi caldwell, chelsea mbakwe, radha dave, navya kondeti abstract. The first one is if a potato core is allowed to dehydrate by sitting in the open air, would the water potential of the potato cells increase or decreas. In this ap lab, i learned more about diffusion and osmosis through the cell membrane and also through organisms and plants.
Molecules smaller than the pores can diffuse through the dialysis membrane along their concentration gradients while molecules larger than the pore size are prevented from crossing the dialysis. Osmosis is a special kind of diffusion where water moves through a selectively permeable membrane a membrane that only allows certain molecules to diffuse. Based on the class data from the baseline tests, you have to design a solution which is isotonic to eggs. In trying to find a cells water potential in different molar concentrations and how the concentrations affect a real cell system, we conducted two labs. In this exercise you will measure diffusion of small molecules through dialysis tubing, an example of a semi permeable membrane. Paul andersen starts with a brief description of diffusion and osmosis. Diffusion is the random movement of molecules from an area of higher concentration to areas of lower concentration. If you dont know what these terms mean, this lab is not going to make sense to you. Other organisms, such as humans, fish, and plants, are multicellular. A more specified form of diffusion is osmosis, what was primarily focused on in this lab, and it is the movement of water across a membrane, again from an area of high concentration to low concentration. Diffusion and osmosis biology 1 flashcards quizlet.
The diffusion of water molecules through a selectively permeable membrane is. Diffusion, osmosis, water potential, calculation of water potential from experimental data, onion cell plasmolysis. This lab would be a simulation of how the membrane works by using a dialysis tubing bag. Diffusion and osmosis overview in this lab you will. Water does just slip through the membrane along with other small, polar molecules such as ethanol and urea. Observation of cells 1 osmosis of cells submerged in isotonic, hypotonic and hypertonic.
Be sure to indicate the movement of water with an arrow in each diagram. He then describes the diffusion demonstration and how molecules move over time. Diffusion and osmosis read through the entire laboratory packet and answer the questions below. Diffusion and osmosis overview the information will assist teachers with aspects of lab 1 that are not necessarily addressed in the lab manual. He then describes the diffusion demonstration and how molecules move. We used an apple shaped cookie cutter and a potato corer to cut out sections of the gel with different surface areas. Students use two phospholipid bilayer models to simulate the movement. Calculation of water potential from experimental data analysis.
Why do red blood cells appear bigger after being exposed to distilled water. Since a semipermeable membrane permits specific things to pass through, some solutes are partitioned. The real cell system in the second lab was a potato. The basic principles of osmosis and diffusion were tested and examined in this lab. Diffusion and osmosis are complex processes, but this kit captures students interest and makes the concepts easier to understand. The purpose of this lab was to understand the mechanisms of diffusion and osmosis as well as there importance to cells by using a model membrane system. This lab taught us about osmosis and diffusion and lead the way into our learning about the cell membrane. Ap biology lab manual for teachers biology junction. Dialysis tubing allows molecules to diffuse through microscopic pres in the tubing. Lab 1 diffusion and osmosis pages 118 lab 1 flow chart should include each of the exercises. Ap biologyinvestigation 4diffusion and osmosispart 1. Osmosis is the diffusion of water through a semipermeable membrane. The objective of this experiment is to develop an understanding of.
The living cells that make up organisms remain alive as long as they are able to. So, group 1 and 2 were paired up, 3 and 4, 5 and 6, and 7 and 8 to exchange data. Osmosis individual data mass of cell set up day 1 initial mass. I have the ap biology lab 1 osmosis and diffusion lab activity due soon, and i cant find the answers anywhere. Plasmolysis is the shrinking of the cytoplasm of a plant cell in response to diffusion of water out of the cell and into a hypertonic solution surrounding the cell as shown below in figure 1.
This is what was observed in the osmosisdiffusion lab. I also learned completely about water potential, what it is, and how it shows where water is moving whether it is moving in or out of a cell or organism. I did this lab many times with my 10th grade regular bio class at kelly high school in. Activity a i predict that the glucosestarch and iki solutions will be present in both the dialysis bag and the cup. We examined the percent increase of mass and molarity of different concentrations of sucrose in the dialysis bag emerged in. Do any of you know where i can find a reliable website with all the information i need. This causes the molecules of the cell to move around and bump into each other. This item has been discontinued by the manufacturer and is no longer available. Objectives before doing this lab you should understand. An alternative way to study surface area to volume ratio using sensors. Vernier conductivity probe and logger pro data collection software was used. Using separate dptps disposable plastic transfer pipettes, place 2 ml of phenolphthalein into each of two test tubes. In class we studied osmosis and how molecules pass through a semipermeable membrane into a solution.
Why is this concept important in studying living things. Some organisms, such as bacteria, are unicellular, which means they consist of a single cell. Hypertonic solutions are solutions with higher amounts of solutes and hypotonic solutions are solutions with a lower amount of solutes. Dialysis tubing, string, plastic cups, distilled water, funnel, sucrose solutions, paper towels, and a balance. Glucose starch water dialysis bag iodine glucose indicator strips the. The processes of diffusion and osmosis account for much of the passive movement of molecules at the cellular level. Obtain data from the other lab groups in your class to complete table 2 osmosis class data. It is true that being polar, the water is more attracted to other water molecules on the same side of the. Diffusion and osmosis modified 2003 from ap bio lab manual introduction. Instead of observing the net change in solute, osmosis follows the net movement of solvent across a semipermeable membrane. Several errors that have or may have occurred in this experiment are 1 some air were inside the bags, which affects the speed of osmosis. Larger or charged watersoluble substances will require a protein carrier. Ap biology laboratory 1 diffusion and osmosis overview in this lab you will. The experiment will show how molecules in a solution are able to move from an area of high concentration to an area.
What is the concentration of the various mystery solutions. The streamlined kit format reduces teacher prep time with required reagents and precut dialysis tubing. In this lab, you will observe the process of osmosis and diffusion. When talking about biological membranes, the phrase concentration gradient is used to describe unequal concentrations of solutes on either side of the. Water is isotonic and moves freely across the cell membrane and helps maintain its fluid mosaic model characteristic. In the prelab, agarose, phenolphtalein, and sodium hydroxide were combined to make the party gel. All matter is composed of very small particles called. Simulation of diffusion through a semipermeable membrane ccby 4. Elodea tip can be purchased from biological supply companies such as connecticut valley.
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