• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Agar blocks

Extracts from this document...

Introduction

Experiment showing rate of diffusion in agar blocks Factors: Size of agar block Concentration of hydrochloric acid (Hcl) Hypothesis: I predict that the bigger the Agar blocks the more time it will take for it to completely diffuse due to the fact that the surface area to volume ratio decreases with size. As for the concentration of the acid I feel that the greater the amount of moles in the acid the quicker the rate of diffusion as the phenolphthalein indicator will diffuse from an area of high concentration to an area of low concentration. Materials and equipment: Beaker Measuring cylinder Knife Agar blocks containing phenolphthalein indicator Ruler Hydrochloric acid Tweezers Stop watch Effect of size on rate of diffusion Procedure #1 1. Cut a pair of agar blocks with a knife to a size 0.5�0.5�0.5 repeat the same for sizes' of 1.0�1.0�1.0 and 1.5�1.5�1.5 2. ...read more.

Middle

to volume ratio 0.5 1.5 0.125 :=12:1 1.0� 6.0 1.000 :=6:1 1.5� 13.5 3.375 :=4:1 Agar block of size 0.5�0.5�0.5 Concentration of Hcl (moles) Time (sec) Average time taken (sec) 1st agar block 2nd agar block 0.75 202.2 204.0 203.1 0.50 258.0 269.4 263.7 0.25 273.0 300.0 286.5 Table 3 Graph for table 1 Figure Graph for table 3 Figure 2 Discussion: The results obtained from this experiment are straight forward. When looking at the "size of the agar block" it can be easily seen that the bigger the agar block the longer it took for the phenolphthalein indicator to diffuse completely, no anomalies are present. The same can be said, when looking at the factor: concentration of Hcl, no anomalies are present whatsoever, and it can be easily deduced that the higher the concentration of acid the quicker the phenolphthalein indicator diffuses. Evaluation of results: The results obtained from the above tables are-as previously mentioned-straight forward, in "Table 1" the reason for the increase in ...read more.

Conclusion

I think that in order to improve this hindrance a more accurate instrument should be used instead of a knife and a ruler, as human error is very easy. Another problem when doing the experiment was that the agar block itself contained different shades of colour ranging from very light pink to dark purple, meaning that the concentration of phenolphthalein indicator was different in some areas of the agar block ,and this obviously tampered with the results. A solution to this problem would be to cut most of the light colour off and only use the darkest part of the agar block, however this would waste most of the agar block. So maybe dip the agar block into phenolphthalein indicator the second it's been cut and then put it into the beaker of Hcl. Conclusion: The hypothesis for both factors was correct, Surface area to volume size largely effects the rate of diffusion as does the concentration the acid being used. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Life Processes & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Here's what a teacher thought of this essay

3 star(s)

***
A reasonably well conducted experiment but a lack of specific detail and scientific terms in the method together with incorrect graph plotting are major shortfalls.

Marked by teacher Adam Roberts 10/05/2013

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Life Processes & Cells essays

  1. Marked by a teacher

    Plan: The effect of the end product, phosphate, on the enzyme phosphatase

    5 star(s)

    When the sodium phosphate combines with the phosphatase, the substrate PPP can no longer fit in since the shape of the active site has changed, therefore there will be less product produced. Less phenolphthalein being produced means there will be less color change in the solution when sodium carbonate is added to the solution.

  2. Marked by a teacher

    The Effect of pH on Catalase

    4 star(s)

    This results in the alteration of shape of the enzyme. The change of shape of the enzyme affects its efficiency to bind temporarily with hydrogen peroxide to catalyse its break down. The change of pH alters the charges on the enzyme, which could alter its shape.

  1. Diffusion in Agar Block

    * 15 Beakers (50ml) - To conduct the experiment in * 1 Measuring Cylinder (25ml) * 1 Stop Watch - To measure the time taken for decolourization * 1 Marker * Distilled Water * 10 Graph Sheets * 1 Blank White Sheet * Pen and Paper - To record the results Variables: There are three types of variables in this experiment.

  2. The effect of acid on the cell membrane

    allows larger molecules such as the anthocyanins, to leak out, and colour the solution of acid the cabbage is in. The pigment is made up of anthocyanins, the sugar free anthocyanins, and can be identified based on the structure of a large group of polymethine dye.

  1. Investigating the effect of changing the concentration of an acid on the rate of ...

    The concentration of the hydrochloric acid will affect the rate of diffusion as well, because the concentration gradient of H+ ions between the acid and the agar piece is steep: The definition of diffusion is "the passive movement of particles of a substance from a region of high concentration (in this case the acid)

  2. To investigate the factors that effect osmosis in living tissue.

    220C is room temperature, 370C is the optimum temperature at which enzymes can act and at 550C many enzymes are denatured and thus inactivated. As mentioned earlier, enzymes are thought to play an important role in carrier-mediated transport even in osmosis, and so inactivating them will thus slow down the rate of osmosis.

  1. Lab Research Paper. Just a Pinch of Salt and a Dash of Bacteria: the ...

    Agar base, a balance, distilled water, a hot plate, a magnetic stirrer, autoclave tape, label tape, and a marker. The next part was Part 2: Making LB Broth. The materials needed were: a 125 milliliter media bottle and a black cap, LB Broth base, a balance, weight boats, distilled water,

  2. GCSE Biology What effects the rate of Osmosis

    I will keep the experiment fair and reliable by taking 18 readings and then taking the average. I will also use the same equipment for each chip and have the same person taking out the chip. I will use a 3 decimal place balance for accurate results.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work