4A+&+4B+_+Exploration

4A : beetroot cell
Hypothesis:**The higher the temperature, the faster the rate of diffusion. The higher the percentage of alcohol, the higher the rate of diffusion. **

Results:

 * Tube || Content || I/O-1 (%) || Colour ||
 * A || 4ml of water || 88.2 || Faint red,almost white ||
 * B || 4ml of 25 % alcohol || 78.5 || Light red,fainter than C ||
 * C || 4ml of 50% alcohol || 28 || Bright red ||
 * D || 4ml of hot water (90-100 || 91.4 || White, faint pink ||
 * E || 4ml of water (cut up pieces) || 80.3 || Pale red,fainter than B ||

Analysis:
1:Tube A was the control of the experiment 2: Each tube serves the purpose of testing only one factor and hence, the result derived will not be confusing as to which is the factor that affected it. 3: yes 4: i had no time to repeat the experiment. 5: Alcohol has less dense than water and hence diffusion will occur. The concentration of alcohol is also a factor too because the higher the alcohol percentage in the tube, the lower its water potential and hence, osmosis would occur as water molecules travel through the beetroot’s selectively permeable membrane to its external environment. The pigment will spread to the tube due to diffusion, however, osmosis helps to distributing the pigment molecules throughtout the tube. 6: E is one of the faster diffusing tubes.This is because the beetroot is cut up into little pieces, to increase the surface area and hence, increase the rate of diffusion. D had a high temperature, a high energy increases the rate of diffusion 7: Temperature and water potential.

Conclusion
The greater the surface area, the greater the rate of diffusion. (tube e) The higher the temperature, the greater the energy for diffusion to occur(tube d).The higher the concentration of alcohol, the greater the rate of diffusion. The external environment for tube b and c have a lower water potential than the beetroot. Hence, osmosis occured as water molecules travelled throught it's selectively permeable membrane to achieve equillibrium.As osmosis occurs, the water molecules carry pigment molecules from the beet root along with it and hence, the external environment turns pink.

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__Exploration 4B: movement in and out of cells__

 * __Hypothesis:__**The greater the surface area to volume ratio, the faster the rate of conductivity.
 * __Results:__**
 * No of pieces of agar cubes || Length(cm) || Surface area(cm^2) || volume(cm^3) || Surface area to volume ratio || Rate of conductivity Change/O-1(mS) ||
 * 1 || 2 || 24 || 8 || 3 || 0.48 ||
 * 8 || 1 || 48 || 8 || 6 || 0.51 ||
 * 64 || 0.5 || 96 || 8 || 12 || 2.11 ||

There is an increasing trend in the rate of conductivity change as the surface area increases. The piece of cube that was cut into 64 pieces had a larger area of exposed surface, and had the highest rate of conductivity change. The rate at which a substance can diffuse is given by **Fick's law**:
 * __Analysis__**
 * Rate of Diffusion a ||  || surface area x concentration difference ||


 * distance ||

Thus, the rate of diffusion depends on the area of exposed surface if the rest of the factors are kept constant.A larger surface area will increase the rate of diffusion as more exchange of materials can occur at the same time. Hence, the limit on the maximum size for a single cell is about 100 mm. In anything larger than this materials cannot diffuse fast enough to carry out life processes. Organisms larger than 100 mm are __multicellular__ to allow efficient exchange of materials between cells and the external environment.
 * Q6&7:** So as organisms get bigger, their surface area/volume ratio gets smaller. As organisms become bigger it becomes more difficult for them to exchange materials with their surroundings.