1. This isn’t preparation for Biology 2.1 AIM: Carry out a short investigation that won’t help you prepare for Biology 2.1

2. Premise Dried apricots are low in water – no surprises there – so if you place one in a beaker of water it will take up water by osmosis. No surprises there either as the cells are still intact so water will move from the beaker into the apricot because the water is moving from an area of high concentration (beaker) to an area of low concentration (apricot) across a selectively permeable membrane. Dried apricots are low in water – no surprises there – so if you place one in a beaker of water it will take up water by osmosis. No surprises there either as the cells are still intact so water will move from the beaker into the apricot because the water is moving from an area of high concentration (beaker) to an area of low concentration (apricot) across a selectively permeable membrane.

3. Task Or will it? Your mission, should you choose to accept it (and you will) is to demonstrate that this uptake of water will occur and then explain it as succinctly and beautifully as I have in the previous slide which you will never, never, never see again. Or will it? Your mission, should you choose to accept it (and you will) is to demonstrate that this uptake of water will occur and then explain it as succinctly and beautifully as I have in the previous slide which you will never, never, never see again. Please note: it would be UNREASONABLE to expect you to compare your results with those of your fellow scientists or compare to any previous research, after all real scientists don’t do that Please note: it would be UNREASONABLE to expect you to compare your results with those of your fellow scientists or compare to any previous research, after all real scientists don’t do that

4. Equipment You have one dried apricot and two friends (or maybe one dried apricot and two other people who might trade results with you), a beaker, water, thermometer, electric scales and a next- to-useless biology teacher who can give you “supervision” (whatever that means). You have one dried apricot and two friends (or maybe one dried apricot and two other people who might trade results with you), a beaker, water, thermometer, electric scales and a next- to-useless biology teacher who can give you “supervision” (whatever that means).

5. Apricots & Osmosis Aim: Aim: Hypothesis: Hypothesis: Independent Variable? Independent Variable? Dependent Variable Dependent Variable Controlled Variables Controlled Variables Number of Repeats Number of Repeats Method Method

6. Results Dried Apricot Weight Change When Placed in Water Trial Initial Weight (g) Final Weight (g) Mass change (g) Percentage weight change Average Percentage Weight Change: You might like to make use of the following table (or not) You might like to make use of the following table (or not)

7. % Mass Change vs % of Original Weight An apricot started at 10 grams and increased to 20g, an increase of 10 grams. An apricot started at 10 grams and increased to 20g, an increase of 10 grams. % mass change = weight gain / initial weight x 100 = 10 / 10 x 100 = 100% % of original weight = final weight / initial weight x 100 = 20 / 10 x 100 = 200%

8. Conclusion Justify your conclusion in terms of the method you used. Justify your conclusion in terms of the method you used. This is about what you did to make it a fair test and why that means your conclusion is correct. This is about what you did to make it a fair test and why that means your conclusion is correct. It isn’t about the things you cocked up or would do differently if you did it again. You’re never going to do it again so do it right in Bio 2.1! It isn’t about the things you cocked up or would do differently if you did it again. You’re never going to do it again so do it right in Bio 2.1! Discussion Evaluation Explain (using your vast knowledge of osmosis) the reason for the results you obtained. Explain (using your vast knowledge of osmosis) the reason for the results you obtained. What did you results show? What did you results show?

9. Other guff you should know after 3.5- 5.5 of years of science at Johnnies… Independent Variable (changing what? & valid range) Independent Variable (changing what? & valid range) Dependent Variable (you’re measuring…?) Dependent Variable (you’re measuring…?) Controlled Variables (how!?) Controlled Variables (how!?) Do experiment right! (method can be changed!) Do experiment right! (method can be changed!) Why do repeats? Why do repeats? How to draw a table, graph How to draw a table, graph Conclusion relates to purpose AND your data! Conclusion relates to purpose AND your data! Discussion uses scientific knowledge to explain trend / pattern in results Discussion uses scientific knowledge to explain trend / pattern in results Evaluate it. Justify what you have said is right by bragging about your: Evaluate it. Justify what you have said is right by bragging about your: Quantity of data Quantity of data Wonderful independent variable range Wonderful independent variable range Removal of sources of error Removal of sources of error Removal of bias Removal of bias

10. Validity vs Reliability Validity: the degree to which a study accurately reflects or assesses the specific concept that the researcher is attempting to measure. We achieve validity by: Validity: the degree to which a study accurately reflects or assesses the specific concept that the researcher is attempting to measure. We achieve validity by: Having a suitable range for our independent variable (at least five!) Having a suitable range for our independent variable (at least five!) Measuring all variables accurately (how many decimal places?) Measuring all variables accurately (how many decimal places?) Controlling all variables not being investigated (and stating how you controlled and measured them) Controlling all variables not being investigated (and stating how you controlled and measured them) Anything else that you might have done to remove error and bias Anything else that you might have done to remove error and bias

11. A List of Controlled Variables Size of apricot Size of apricot Length of time Length of time Concentration for each repeat Concentration for each repeat Glad wrap to prevent evaporation Glad wrap to prevent evaporation Same equipment Same equipment Temperature of repeat Temperature of repeat Apricots from same bags (controls species variation, variation in dryness) Apricots from same bags (controls species variation, variation in dryness) Removed excess water from wet apricots Removed excess water from wet apricots

12. Validity vs Reliability Reliability: the extent to which an experiment, test, or any measuring procedure yields the same result on repeated trials. Reliability: the extent to which an experiment, test, or any measuring procedure yields the same result on repeated trials. We achieve this by carrying out repeats (at least three!) and averaging the data We achieve this by carrying out repeats (at least three!) and averaging the data

13. Apricot Osmosis Experiment Apricot mass in tap water TrialMass % change Nick142 Braden130 Tyler177 William289 Dion208 Matytthew207 Adrian246 Madoc200 Cam190 Average199 Apricot mass in salt water TrialMass % change Hamish110 Chris117 Hugh131 Sam122 Michael141 Masaaki116 Average123 Apricot Osmosis Experiment Apricot mass in tap water TrialMass % change Jacob229 Max172 Carter185 Tim195 Ru181 Marc180 Saba208 Yuhei196 Hugh183 Chris273 Average200 Apricot mass in salt water TrialMass % change George193 Ben119 Ben130 Average147

14. Practice Plan Design an experiment to find out what will happen in terms of osmosis to celery sticks placed in different salt concentrations. Background: concentration of salt in celery is 0.5 mol / L. You have lots of celery, 5 x 30cm sticks of celery each. Concs of salt solutions available. Distilled water, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1,1.2, 1.3, 1.4, 1.5 mol / L salt concs. Complete the following: Aim, Hypothesis, Variables (independent, dependent, controlled), Equipment, Method.

15. Observing Osmosis in a Cell

16. Problem Problem hard to see osmosis occurring in microscopic cells. hard to see osmosis occurring in microscopic cells. Solution Solution use a large cell like a chicken egg use a large cell like a chicken egg Problem Problem shell impermeable to water. shell impermeable to water. Solution Solution remove shell (dissolve in acetic acid – vinegar) remove shell (dissolve in acetic acid – vinegar) Reaction: Calcium carbonate + Acetic acid  H 2 O + CO 2 + Calcium Acetate Chemists: write the formula, try to balance! (Acetic acid: Acetate ion: (Acetic acid: CH 3 COOH, Acetate ion: CH 3 COO - )

17. Dissolve shell Dissolve shell Place in water Place in water Weigh Weigh Measure 200mL sugar solution Measure 200mL sugar solution Put egg in, leave 48 hours. Put egg in, leave 48 hours. Weigh, measure solution volume Weigh, measure solution volume Expect: egg mass drop, solution volume increase Expect: egg mass drop, solution volume increase

18. Observations +30mins: Bubbles of CO 2 on egg Observations +48hrs (day 3): Place egg in 250mL of a hypertonic sugar solution Place egg in 250mL of a hypertonic sugar solutionPrediction: Observations +48hrs (day 5): - Egg:Liquid Volume Observations +48hrs (day 7): - Egg:Liquid Volume Questions Questions 1. What happened to the egg? Why? 2. What happened to the liquid volume? Why 3. What could you do to reverse what happened?

19. Elodea Plasmolysis

20. Make a wet mount of elodea and add saltwater to the slide. Observe what happens to the cells after 15min. (make a control (no salt) for comparison). Observations: Conclusions: Questions: Is plasmolysis reversible? What could you do to test this?

22. See: http://www.biologycorner.com/worksheets/plants_and_salt.htmlhttp://www.biologycorner.com/worksheets/plants_and_salt.html For a clip on cytoplasmic streaming

23. Isotonic Concentration of Carrots Aim: to find out the isotonic concentration of carrots

24. Isotonic concentration of carrots Write: Write: Aim Aim Independent variable Independent variable suitable range, how to change it suitable range, how to change it Dependent variable Dependent variable what, how to measure what, how to measure Controlled variable Controlled variable List each and how to measure and check List each and how to measure and check

25. Carrot Mass Change in Different Salt Concentrations Salt concentration (g / 100mL) Initial Weight (g) Final Weight (g) Mass change (g) Percentage weight change Average percentage weight change 0 0 0.5 1 1 1.5 2 2 2.5 3 3

26. Dummy Data

27. Questions What happened in distilled water? Explain What happened in distilled water? Explain What happened in the saltiest concentration? Explain What happened in the saltiest concentration? Explain How did you identify the isotonic concentration? How did you identify the isotonic concentration? How did you make sure the experiment was valid? How did you make sure the experiment was valid? How did you make sure the experiment was reliable? How did you make sure the experiment was reliable?