To complete this laboratory work, you must recall the material covered on the topic "Osmosis and Diffusion." Using a notebook - synopsis or textbook provided by your science tutor for learning theory. Research reveals common student misconceptions in the fields of diffusion and osmosis. In particular, students find it challenging to understand that cells, like multicellular organisms, live in the environment and must perform all the actions necessary to stay alive. Common student misconceptions also include misconceptions about the difference between cells and molecules and the difference in size between proteins, molecules, and cells.
You can make a lab report on osmosis and diffusion within a few days. Thanks to this experiment, students will learn about all living organisms' structural units - the cell and its structure and functions. When doing tasks, it will be necessary to move molecules in and out through the cell membrane and interact with the environment.
To understand what osmosis and diffusion, it will be necessary to draw up conceptual maps and study the process of laboratory reporting using real examples and prove how the two concepts are related. To develop an experiment, the student needs to show their knowledge and experience in the study of osmosis and diffusion. Based on the results, the student will understand how semipermeable the membrane is.
All students need to make a basic lab report on diffusion and osmosis, because thanks to it, you will know how different substances move through cell membranes. For example, diffusion occurs across a semipermeable membrane. But also for its process, there must be no barrier, that is, a membrane. When making a diffusion experiment, factors such as temperature, molecular weight, electrical charge, and substance concentration must be considered. In turn, you will see that using this method, water moves according to the same principle - this will be osmosis.
Osmosis is a selective form of diffusion. Diffusion is based on the random flow of molecules and is much more common in gases, while osmosis base on the molecules' inherent ability in the water. The membrane in osmosis allows certain types of molecules to pass through, limiting the influx of other types.
In both osmosis and diffusion, molecules necessarily flow from an area of higher concentration to a lower one. A practical example of diffusion is when you spray a room freshener in a corner, and the whole room soon filled with scent. A practical example of osmosis is when you start feeling thirsty after eating something salty, as excess salt attracts water to the cells in the body.
Diffusion and osmosis have an essential role in living organisms to support "homeostasis," "internal balance or equilibrium to regulate various mechanisms through cellular function." Recently, osmosis has also been used as a poetic concept and defines an educational concept in which a child learns by observing, interacting, and simply being in teachers and fellow students' company.
The diffusion of water molecules through a selectively permeable membrane is osmosis. Osmosis is crucial to our existence, as the process of osmosis maintains homeostasis (relatively stable environment) in the human body and allows the exchange of nutrients between cells (Palaparthi, 2017). The rate of osmosis is affected by temperature, pressure, and size. In temperature, more heat causes more energy. More energy allows the molecules to collide more, which gives away to faster diffusion rates. More pressure causes more molecules to collide. Colliding molecules rub off energy, causing diffusion rates to increase. The larger the cell size, the more energy required for diffusion, thus elongating the time of diffusing, consequently decreasing the rate. The rate of diffusion relative to cell size was tested when three agar cubes of different sizes were measured after being placed in cups of vinegar for 10 minutes. A hypothesis suitable for this experiment is if the surface area of the cell size is larger, the extent of the diffusion in percentages would decrease as it would take a longer time for diffusion to take place within the cell if it has a larger surface area.
When a cell has a higher solute concentration than the environment, water will move into the hypertonic cell through osmosis. When a cell has a lower solute concentration than the environment, water will diffuse out of the hypotonic cell through osmosis in order to achieve equal concentrations, in which the cell would be isotonic. The concept of cell size was demonstrated in measuring the mass of 18 turnip cores before and after being placed in six beakers filled with different sucrose molarities. A hypothesis suitable for this experiment is if the molarity of the sucrose concentrations increases, then the cell's size would initially be increasing less and eventually the cell's size would be decreasing. Water molecules, initially, would be diffusing into the turnip core, but the water would be diffusing out of the turnip core later on as the molarity is increasing.
In the second experiment testing rates of diffusion relative to the surface area, 3 agar cubes of different sizes (1cmx1cmx1cm (control to compare with), 2cmx2cmx2cm, and 3cmx3cmx3cm (independent variables)), were carefully formed from one huge agar block. Afterward, the volume, surface area, and the SA:V ratios were measured. The agar cubes were then placed in a solution of white vinegar for 10 minutes and were measured afterward for the extent of diffusion. The extent of diffusion, the dependent variable, was measured by subtracting the volume of the cube that was uncolored from the total volume of the agar cube divided by the total volume of the agar cube. The percentages were recorded for each agar cube.
We performed dialysis tubing, where a bag of 1% starch solution was placed into a cup of water with IKI for 30 minutes. After the 30 minutes, the bag changed into a dark, purple color, indicating that IKI diffused into the bag and the glucose and starch became evident. A chemical interaction occurred between the IKI and the starch, which caused the bag to turn into a black color. This demonstration showcases the scientific process of diffusion in simple terms for us as students, which was taught to us in the classroom. This process of diffusion is played out in our own bodies! Our cells' selectively permeable cell membrane allows different substances to diffuse in and out of the cell in order to maintain homeostasis (isotonic). This is known as osmoregulation.
As shown here, the extent of diffusion is recorded. A trend is evident here: the bigger the cell size, the less diffusion takes place. As the cell size increases, the amount of diffusion that takes place decreases as more energy is required for diffusion to take place, making the process of diffusion longer.
These two experiments showed to us on a small scale something very complicated on the microlevel. The turnip experiment showed cells' responses to different environments. In our turnip experiment, we were able to find a significant trend: As the molarity increases, the cell size decreased. The cells, initially, were increasing less (dH2O --> 7.41%, then .2M --> 3.91%), but the cells did increase in mass as the cells were placed in a hypotonic solution. The sucrose solution surrounding the turnip core diffused inside of the cells in order to achieve equilibrium. Eventually, as the molarity increased, the turnip core began to shrink (.4M --> .79%, then .6M --> -.91%). This is because the water inside the turnip core began to diffuse out of the cell and into the sucrose solution, which decreased the size of the turnip cores because the cell was placed in a hypertonic solution. This experiment demonstrates what occurs inside our bodies, where a cell performs osmoregulation (maintains fluidity balance in the organism, as mentioned in Chen, 2019). In the cell size experiment, a significant trend was found as well: As the surface area decrease, the rate of diffusion increased. In the 1cmx1cmx1cm agar cube, the rate of diffusion was 29.7% faster than the rate of diffusion in the 2cmx2cmx2cm agar cube, in which the rate of diffusion for the 2cmx2cmx2cm agar cube was 25.7% faster than the rate of diffusion for the 3cmx3cmx3cm agar cube. The reason that this trend exists is that as the cell gets bigger, it takes diffusion a lot longer to take place.
When a cell membrane is said to be selectively permeable, it means that the cell membrane controls what substances pass in and out through the membrane. This characteristic of cell membranes plays a great role in passive transport. Passive transport is the movement of substances across the cell membrane without any input of energy by the cell. The energy for passive transport comes entirely from kinetic energy that the molecules have. The simplest type of passive transport is diffusion, which is the movement of molecules from an area of high concentration to an area of lower concentration. Diffusion moves down the concentration gradient, which is the difference in the concentration of molecules across a space. Osmosis is a type of diffusion in which water molecules move down the concentration gradient.
A few errors may have happened over the course of this experiment. The washing of the egg could have affected the mass. Also, the jars might not have been thoroughly cleaned out before putting in the next substance. This could have affected the rate of diffusion because it would have changed the concentration of the solute particles. These errors and a few others may have occurred.
~~6. Report the "Ending Average Volume (cubic millimeters)" and the (positive or negative) "Percent Differences" that you observed in the osmosis experiment for each salt solution below. (These should be recorded in data Table 1 from the Lab 4 Procedures step 2b.) (8 points)
~~16. How might the information gained from this lab pertaining to cell structures and diffusion be useful to you, or how can you apply this knowledge to your everyday life as a non-scientist? The application will be graded according to the rubric below. (20 points) 2b1af7f3a8