Tuesday, 12 February 2013

2.16 describe experiments to investigate diffusion and osmosis using living and non-living systems

Diffusion
Put a coloured substance (like food colouring) into a clear one (like water)
Time how long it takes for all the liquid to be the same colour.
Change the temperature of the liquid and make observations.
The higher the heat, the more kinetic energy meaning the colour moves through the liquid faster.

Osmosis
Cut two roughly equal pieces of potato and weigh them.
Put one in distilled water and one in salt water.
After a given amount of time weigh them.
The one in salt water will have lost mass as the water in the potato moves to the more highly concentrated salt water. Where as in the pure water the potato will have gained mass as it was less dens with water.

47 comments:

  1. Hi Hannah,
    I discovered your/this blog just today as I was revising biology with my friend, and it is an absolute godsend!
    Thank you so much for doing this, you hero

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  2. Hahaha, thank you very much! Glad to help ;)

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  3. I agree entirely, I can't believe I didn't find this sooner!!!
    Thank you so so much!

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  4. One word for you: LIFESAVER (!)

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  5. Thank you so much, you've helped me out so many times!!

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  6. This is class but it is IGCSE or GCSE?

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    Replies
    1. Ah, its IGCSE.. I should probably change the title :P

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    2. How was Gcse's? Hard or easy?

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    3. How was Gcse's? Hard or easy?

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    4. good luck Bright Boss, how are your mocks going?

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  7. Guys thank you for all these comments :) I'm happy that you're finding the blogs helpful!

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  8. Hi Hannah im finding you blog incredibly useful thanks so much for making it it must have taken a huge effort and seems to be helping a lot of people! Im just wondering about the investigating diffusion and osmosis in living and non-living systems, iv been googling it to find out about non-living system experiments but am not sure im either grasping that meaning or finding something for a non-living system experiment, am i being a total dummy?

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  9. Hey frau punk ;) Thank you for your comment! The examples given are of non-living systems (although a potato is from a plant, the potato itself is not a whole system, so I'm not counting it as living) so basically they show diffusion and osmosis in general. Experiments for living things show osmosis and diffusion in the plant and animal kingdoms: examples would be for osmosis seeing how long it takes coloured water to climb up a plants stem; and for diffusion collecting gas in a upturned tube above a water plant. Does that answer the question?

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  10. this is wrong, the water moves from potato into MORE highly concentrated salt water

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    Replies
    1. Thank you! has been rectified.

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    2. No, you are wrong. The water moves by osmosis from and are of high concentration (inside the cell) to an area of low concentration of water (outside the cell) as the salt water has a lesser water potential (concentration) becuase it has been diluted with substance being salt and has become a solution and so is not pure water like distilled water.

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    3. No, you are wrong. The water moves by osmosis from and are of high concentration (inside the cell) to an area of low concentration of water (outside the cell) as the salt water has a lesser water potential (concentration) becuase it has been diluted with substance being salt and has become a solution and so is not pure water like distilled water.

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    4. loooool this comment got me creasin i don't even know why

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  11. OMG your are an actual lifesaver! I found this and told all my friends! It so much easier to use this blog than bitesize or any other website like that
    I don't even know you and I love you :)

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  12. you are incredible! wish id found this earlier, have my bio exam tomorrow ._.
    thank you thank you thank you!!!
    wish me luck
    greets

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  13. Can you give me an example of diffusion in living organisms? please and thankyou for your help

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  14. This blog is really useful- plus its relatively well known- for my biology revision i took some stuff from your website- when i got to school when it was due in my friend asked where i got my information from i said it was from a this blog- turns out he got it from the same place! THANK YOU HANNAH!

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  15. Absolutely amazing blog, so helpful, thank you so much :)

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  16. This really helped me with my revision for biology! Thank you for your help!

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  17. Hannah if a dead rat is used for an experiments on osmosis explain the processes to me

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  18. Enter your comment...this is cool

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  19. You don't need to know about a living system experiment for diffusion, only non-living (agar cubes). For osmosis you need to know about living (the potato one as previously explained) and non-living which is with Visking tubing:
    1)pour sugar solution into Visking tubing
    2) tie off tubing at ends with a wire at the bottlow and a glass rod inserted at the top with wire wrapped around
    3) put the tubing piece into a beaker of pure water and measure where the sugar solution comes up to on the beaker
    4) leave overnight, measure next day where the solution in the visking tubing comes up to and it should have increased
    Why: because the differing concentration gradient with the low in water solution in the visking tubing and the high concentration of water in the beaker.

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  20. It’s a wave like contraction expansion of gut muscles that push the food through the gut.

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  21. This comment has been removed by the author.

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  22. Suggestion:

    Diffusion
    Put known mass of potassium permanganate into beaker of water (i.e. 500cm3).
    Time how long it takes for all the liquid to become purple.
    Change the temperature of the water and record results.
    The higher the temperature, the more kinetic energy the particles have - the KMnO4 moves through the liquid faster.

    Osmosis
    Cut two equal pieces of potato into two potato chips and then weigh them.
    Put one in distilled water and one in salt water of a known concentration.
    After a given amount of time (i.e. 1 hour) weigh them.
    The one in salt water will have lost mass, as the water in the potato moves to the more highly concentrated salt water. Whereas in the pure water, the potato will have gained mass as it had a lower concentration of water:

    Water moves from high water conc. - in the beaker
    TO
    Low water conc. - in the potato chip

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  23. Suggestion:

    Diffusion
    Put known mass of potassium permanganate into beaker of water (i.e. 500cm3).
    Time how long it takes for all the liquid to become purple.
    Change the temperature of the water and record results.
    The higher the temperature, the more kinetic energy the particles have - the KMnO4 moves through the liquid faster.

    Osmosis
    Cut two equal pieces of potato into two potato chips and then weigh them.
    Put one in distilled water and one in salt water of a known concentration.
    After a given amount of time (i.e. 1 hour) weigh them.
    The one in salt water will have lost mass, as the water in the potato moves to the more highly concentrated salt water. Whereas in the pure water, the potato will have gained mass as it had a lower concentration of water:

    Water moves from high water conc. - in the beaker
    TO
    Low water conc. - in the potato chip

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  24. Whereas is one word. You have spelled it as where as.
    Dens is meant to be dense

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  25. Anyone please help I have a very important question
    I've looked at some past paper questions and one of them asks why has the mass lost and gained been converted to percentages, I don't have any answers for this and I need to make notes can anyone give a reasonable answer

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  26. This comment has been removed by the author.

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  27. I have this if anyone wanted some extra detail:

    2.16 Describe experiments to investigate diffusion and osmosis in living and win living systems.

    Diffusion living - EXPERIMENT to show the effect of temperature on diffusion in beetroot

    Independent variable - Temperature
    Dependent variable - Rate of Diffusion

    Method :
    Cut cylinders of beetroot using a cork borer, wash any pigment from the cut surfaces
    Place the beetroot in boiling tubes and add water to each
    Place the test tube in one of five different water baths at different temperatures
    Leave for 15 mins and then place side by side in a test tube rack
    Fill cuvettes with each of the solutions and take absorbance readings

    Higher temperature means higher rate of absorbance/higher rate of diffusion. At higher temperatures the pigment molecules had more kinetic energy to diffuse.

    Diffusion non-living - EXPERIMENT to show the effect of concentration of a substance o the rate of diffusion

    Independent variable - Concentration
    Dependent variable - Rate of Diffusion

    Method :
1) Set up a glass tube with small squares of damp red litmus paper spaced equally apart long its length in a fume cupboard.
    2) Add 1 drop of ammonia solution to come cotton wool and use tweezers to place the cotton wool at one end of the tube.
    3) Close the tube with a bung and time how long it takes for each litmus paper to change colour.
    4) Repeat the experiment but this time, use 3 drops of ammonia.

    The further away the ammonia from the litmus, the longer diffusion takes so the longer it takes for the colour change. “The higher the concentration of ammonia, the faster the rate of diffusion.” This is because there are more particles in the given volume to diffuse so it is quicker.

    Osmosis living - EXPERIMENT to show how the concentration of sucrose affects the rate of osmosis

    Independent variable - Concentration of sucrose
    Dependent variable - Rate of Osmosis

    Method :
    Cut 6 different pieces of potato using a cork borer and measure them to the correct size
    Weigh the pieces and record them
    Prepare 6 test tubes with sucrose solution. Each test tube needs a different concentration. Write the concentration on each test tube
    Starting with 0%, put the potato into the corresponding test tube and leave it for 15 minutes.
    Remove the potato and pat dry. Record the new weight.
    Repeat with each concentration and work out the percentage change.

    At 5.2 sucrose concentration, the sucrose solution was isotonic and no net movement of water took place. Below 5.2, the mass of the potato increased (hypotonic sucrose solution) and above 5.2, the mass of the potato decreased (hypertonic sucrose solution). After 5.2%, the higher the sucrose concentration, the more mass decrease.

    Osmosis non living - EXPERIMENT to investigate the relationship between the rate of osmosis and concentration of sucrose.

    Independent variable - Concentration of sucrose solution
    Dependent variable - Rate of Osmosis

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  28. aaaagggghhhh bio igcse ppr 1 tommorrow!!!!!
    thanx ppl

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  29. The Biology Syllabus has changed.... New Syllabus Blog:

    http://igcse-biology-2017.blogspot.hk

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  30. look at

    http://igcse-biology-notes.blogspot.hk/2017/06/216-describe-experiments-to-investigate.html

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