How can the surface area of a block of agar be increased without changing its overall volume?
How can the surface area of a block of agar be increased without changing its overall volume?
They can increase their surface area by flattening and becoming longer or by having a rough surface with lots of folds of cell membrane known as villi.
Why do agar cubes turn pink?
When phenolphthalein is exposed to the normal alkaline conditions in the agar, it will look pink. But when it is exposed to neutral or acidic conditions, it changes from pink to clear. You will make different size and shaped agar cubes as a model for cells to study the impact of cell size and shape on diffusion rate.
How do you make agar cubes for diffusion?
Diffusion
- Mix 20g of agar with one liter of distilled or deionized water. Recipe based on 15 groups of students working in pairs.
- Heat almost to a boil. Stir frequently until solution is clear.
- Remove from heat.
- Pour agar into a shallow tray to a depth of 3cm and allow it to set (over night).
Which agar cube would be more efficient as a cell?
The most effective will be the 4:1 ratio, cube C, because, as stated above, the larger ratios are the ones that with hold the most maximization for diffusion. The smaller the cell (bigger the ration) the more adequate it is to have substances moving in and out of it.
Can surface area be bigger than volume?
The surface area can never be greater than the volume of any shape. Neither can the volume ever be greater than the surface area. Why? Because they have different units, saying one is greater than the other does not make much sense.
How do you work out volume and surface area?
Remember that volume is measured in units cubed: mm 3, cm 3, m 3 etc. To calculate the surface area of a cuboid you calculate the area of each face and add them together. Remember that area is measured in units squared: mm 2, cm 2, m 2 etc.
What cell shape is the best for keeping a cell alive?
Therefore, if a cell is going to be spherical, it would be best to be the smallest sphere possible, because decreasing size increases the surface-to-volume ratio (i.e., the volume decreases faster than does the area that can service it with nutrients).
What does vinegar represent in agar cubes?
As an acid, vinegar has a large number of hydrogen ions. When the hydrogen ions come into contact with the pH indicator, the solution changes color. Fill a clear container with vinegar to a 3-cm depth. Place one agar cube of each size in the vinegar, making sure the blocks are submerged.
What do agar cubes represent?
The agar cubes represent biological cells. The volume of the cube correlates to the cytoplasm and the surface area of each cube to the cell membrane. All living cells are dependent on diffusion processes for survival. These processes transport materials across the cell membrane into and out of the cell.
What are agar cubes used for?
Use cubes of agar to investigate how cell size impacts diffusion. All biological cells require the transport of materials across the plasma membrane into and out of the cell. By infusing cubes of agar with a pH indicator, and then soaking the treated cubes in vinegar, you can model how diffusion occurs in cells.
Why does sodium hydroxide diffuse into cube?
We know the sodium hydroxide diffuses into the agar cube because the cube turned purple as it entered the cube containing the phenolphthalein, an indicator of base.
Why are cells so small lab?
Cells remain small because all materials that are exchanged between the cell and its environment, like oxygen and glucose, must pass through the cell membrane. If materials cannot be exchanged efficiently, then the cell could die.
Why do agar cubes turn pink in NaOH?
In this experiment, you will use agar cubes to which the indicator phenolphthalein has been added. Phenolphthalein is an acid/base indicator that turns pink in the presence of a base such as NaOH. Thus the surface of the agar cubes will turn pink immediately when put into a NaOH solution.
How do you change the color of agar cells?
When the hydrogen ions come into contact with the pH indicator, the vinegar changes color. Fill a clear container with vinegar to a 3-cm depth. Place one agar cube of each size in the vinegar, making sure the blocks are submerged. The untreated blocks (one of each size) will be used for comparison.
What happens when you put agar cubes in vinegar?
When the hydrogen ions come into contact with the pH indicator, the solution changes color. Fill a clear container with vinegar to a 3-cm depth. Place one agar cube of each size in the vinegar, making sure the blocks are submerged. The untreated blocks (one of each size) will be used for comparison. What do you think will happen to each cube?
How does diffusion occur in an agar cube?
Diffusion occurs when molecules in an area of higher concentration move to an area of lower concentration. As hydrogen ions from the vinegar move into the agar cube, the color of the cube changes, allowing you to see how far they have diffused.
What happens when you put NaOH in an agar cube?
As the NaOH solution penetrates inside the cube, the Phenolphthalein in the agar cubes will release and the agar cube will turn colorless. The time for the agar cubes to completely turn colorless was noted.
What’s the difference between agar cubes that turn pink?
Smaller agar cubes on average turned pink faster than larger agar cubes. The outer part of the agar cube almost instantaneously tuned pink, while the inner area of the cube took longer to turn pink. There seems to be a trend in increasing times for the agar cube to turn pink as the trials progress.
When the hydrogen ions come into contact with the pH indicator, the vinegar changes color. Fill a clear container with vinegar to a 3-cm depth. Place one agar cube of each size in the vinegar, making sure the blocks are submerged. The untreated blocks (one of each size) will be used for comparison.
What causes molecules to move in an agar cube?
While random molecular motion will cause individual molecules and ions to continue moving back and forth between the cube and the vinegar solution, the overall concentrations will remain in equilibrium, with equal concentrations inside and outside the agar cube.
