Essay about writing assignment 2

Certain substances are able to diffuse across plasma membranes under the right conditions through selective permeability. The selection of these certain substances allows for cells to maintain homeostasis, as these substances move from higher concentration to lower concentration. The purpose of this experiment is to see whether or not Lugol’s will be able to diffuse across dialysis tubing, which acts as a membrane. Lugol’s turns black when it interacts with starch, which will make the diffusion easy to see. This is all based off of a caterpillar eating a plant. The starch present in the leaves causes the caterpillar to produce amylase, which breaks down starch. In one experiment, the tubing will contain starch and amylase, while the other tubing

6. Many drug safety research studies are sponsored by pharmaceutical companies that would financially benefit if the results of the study are favorable. Is this an example of a potential confounding factor?

During reconstruction, the meaning of freedom suited many different types of interpretation; the perception of freedom between former slaves and their slaves masters were very contradictory. To begin with, African-Americans had suffered severe abuse over those years of slavery, so to them, the meaning of freedom was basically a hope that in the future, they won’t experience all kind of punishment and exploration that they have been experienced so far. Besides that, formers slaves were demanding equal civil and political rights. In the same way, they valued their freedom by establishing their own schools and churches, reuniting families that were separated under

In this lab experiment, half our group observed and measured osmosis using dialysis tubes that were represented as the semipermeable membrane. It is permeable to water and other small molecules but is impermeable to larger molecules such as the sucrose solution used in each of the four beakers and tubing. The other half of our group observed the tonicity of sheep blood to determine whether the blood was isotonic, hypotonic, or hypertonic. The 85 g/dL of NaCl solution was the ideal isotonic number in relation to the sheep blood cells as well as a reference to the other observations of the solutions.

The purpose of these experiments is to examine the driving force behind the movement of substances across a selective or semiperpeable plasma membrane. Experiment simulations examine substances that move passively through a semipermeable membrane, and those that require active transport. Those that move passively through the membrane will do so in these simulations by facilitated diffusion and filtration. The plasma membrane’s structure is composed in such a way that it can discriminate as to which substances can pass into the cell. This enables nutrients to enter the cell, while keeping unwanted substances out. Active

Dialysis tubing is a membrane made of regenerated cellulose fibers formed into a flat tube. If two solutions containing dissolved substances of different molecular weights are separated by this membrane, some substances may readily pass through the pores of the membrane, but others may be excluded.

But for another example a pizza shop in competition wit a fried chicken shop would be indirect because the products are not the same but they are still competing for sales.

A major determinant of diffusion in a biological system is membrane permeability. Small, uncharged molecules pass through cellular membranes easily, while most and/or charged molecules cannot pass through the membrane. The movement of water across a selectively permeable membrane, like the plasma membrane

Exercise 1: Cell Transport Mechanisms and Permeability: Activity 3: Simulating Osmotic Pressure Lab Report Pre-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1. Which of the following is true of osmosis? You correctly answered: c. It is a type of diffusion. 2. Which of the following occurs when a hypertonic solution is added to cells? You correctly answered: d. The cells shrink. 3. The variable that affects osmotic pressure is You correctly answered: a. the concentration of nondiffusing solutes. 4. The net movement of water would be into the cell in a You correctly answered: b. hypotonic solution.

In this lab, neutral red was used as a pH indicator. The color changes from yellow to red in a basic solution to an acidic solution. The neutral red dye was applied to Saccharomyces Cerevisiae. When the S. Cerevisiae cells come in contact with the neutral red dye, the dye gets to the cell by crossing the cell membrane. The cell membrane is the outer surface of the cell that functions as a barrier. The outside of the cell membrane is made of lipid and membrane proteins (Hardin, 2012). It is selectively permeable, which means only select ions and molecules can pass through it by transport. Membrane transport can be actively or passively moving a substance from side of the membrane to another (Hardin, 2012). Passive transport does not require energy to move molecules across the cell membrane. Diffusion is a form of passive transport that moves molecules across the membrane from an area of higher concentration to an area of lower concentration. Osmosis, diffusion, and facilitated diffusion are all examples of passive transport. Active transport requires energy to move molecules across the membrane from areas of lower concentration to higher concentration. It requires energy because it pushes sodium ions (Na+) and potassium ions (K+) (Hardin, 2012). When the dye entered the cell, it also showed its location. Sodium azide (Na+N3-) is a metabolic inhibitor that blocks the flow of electrons along

Question #1 is worth 5 points – all others are worth 1 point each. Either type your answers directly onto THIS sheet OR create a new file and number your answers 1, 2, 3, etc.

Our objectives were to prepare varying molar solutions, determine isotonic and hemolytic molar concentrations of electrolytes and non-electrolytes, and to determine the permeability of a membrane and the diffusion rate for different compounds. In preparing the various molar solutions, we mixed five different concentrations of NaCl with water and five different concentrations of glucose with water.

1. Describe how you've used media over the last few days in these four areas: cognition, diversion, social utility, and withdrawal. Now describe how the media has helped you during this same period in terms of: surveillance, interpretation, linkage, entertainment, and formulating values.

In this hypotonic solution a net diffusion of water into the cell occurs, there is also high turgor pressure within the cell – this causes the cell to grow and to possibly burst. This is shown when the colour inside the dialysis tube has changed from a rust colour to a dark purple, since the iodine is in the presence of starch. The test result that showed the highest rate of osmosis is the hot water solution. In the hot water solution, it showed how the rate of water passed through the semi permeable membrane of the dialysis tubing faster than the cold water. This proved that cold water showed the lowest rate of

With this experiment, the affect of surface area to volume ratio on the rate of diffusion is investigated. Four agars containing phenolphthalein, an indicator that turns colorless in acid, each ranging in size were used. In this experiment, the agar cubes represent cells and the time it took for cubes to turn colorless shows the rate of diffusion. Next, the cubes were placed in a beaker and just enough hydrochloric acid was added to cover them. Then, the time it took them to turn colorless was measured. It was observed that when volume increases, so does the surface area, but more so. For example, the volume of the smallest cube was 0.125cm3 while it’s surface are was 1.5 cm2. The difference of volumes between the smallest and