Diffusion/Osmosis Osmosis Diffusion Intro - YouTube Osmosis Diffusion Intro - YouTube.
Osmosis Practical Write UP
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L1 L3 L5 A Use apparatus skilfully and safely L4/5 i) Apparatus and materials are handled correctly and safely and manipulative techniques are used in an appropriate and safe manner. Personal safety precautions considered Some care taken to follow safety procedures. Appropriate techniques attempted. Some elements of risk involved in using equipment and chemicals is considered Personal safety precautions considered Investigation carried out safely with effort given to appropriate use of techniques Full risk assessment in using equipment and chemicals is considered and safety precautions are prepared before investigation Investigation carried out with safety as a priority. All manipulative techniques used with skill NONE B Produce and record reliable and valid results L5 i) Measurements and observations are made with precision and recorded in a structured manner; variables are identified and the validity and reliability of results are justified. Student follows teacher's plan Independent and Dependent variables identified. Appropriate equipment is used to make measurements over an inappropriate range Most measurements are performed with accuracy but the methods used to acquire these are not justified e.g. measure at eye level An appropriate number repeats are planned for but not completed A table of results is built but has errors on decimal places and/or units and is disorganised Student follows teacher's plan and makes attempts to enhance the plan with their own ideas based on their experience and research. Appropriately precise equipment is used to make measurements over an appropriate range All measurements are performed with accuracy and the methods used to acquire these are justified e.g. measure at eye level An appropriate number repeats are planned for and completed A detailed, neat and complete table of results is built but has errors on decimal places and/or units Student refers to published data to support their conclusions and therefore enhance the validity of their findings Student generates a plan with their own ideas based on their experience and research. Controls and/or placebos are considered and the use of blind and double blind trials are evaluated. Appropriately precise equipment is justified in its use and is used to make measurements over an appropriate range All measurements are performed with accuracy and the methods used to acquire these are justified e.g. measure at eye level A detailed, neat and complete table of results is built Student conducts research into published data to support their conclusions and therefore enhance the validity of their findings (all references annotated correctly) L3/4 ii) Possible systematic errors and random errors in generating Student identifies a possible confounding All possible 'confounding' variables are identified and efforts described to All possible 'confounding' variables are identified and efforts described to reduce their effects (Random errors)
description
This is a small write up for the Osmosis Core Practical - Edexcel.
Transcript of Osmosis Practical Write UP
L1L3L5
AUse apparatus skilfully and safely
L4/5Comment by Martin Mullan: i) Apparatus and materials are handled correctly and safely and manipulative techniques are used in an appropriate and safe manner.Personal safety precautions considered
Some care taken to follow safety procedures.
Appropriate techniques attempted.Some elements of risk involved in using equipment and chemicals is considered
Personal safety precautions considered
Investigation carried out safely with effort given to appropriate use of techniquesFull risk assessment in using equipment and chemicals is considered and safety precautions are prepared before investigation
Investigation carried out with safety as a priority.
All manipulative techniques used with skillComment by Sanngeeta Nadarajan:
NONE
BProduce and record reliable and valid results
L5Comment by Martin Mullan: i) Measurements and observations are made with precision and recorded in a structured manner; variables are identified and the validity and reliability of results are justified.Student follows teacher's plan
Independent and Dependent variables identified.
Appropriate equipment is used to make measurements over an inappropriate range
Most measurements are performed with accuracy but the methods used to acquire these are not justified e.g. measure at eye level
An appropriate number repeats are planned for but not completed
A table of results is built but has errors on decimal places and/or units and is disorganisedStudent follows teacher's plan and makes attempts to enhance the plan with their own ideas based on their experience and research.
Appropriately precise equipment is used to make measurements over an appropriate range
All measurements are performed with accuracy and the methods used to acquire these are justified e.g. measure at eye level
An appropriate number repeats are planned for and completed
A detailed, neat and complete table of results is built but has errors on decimal places and/or units
Student refers to published data to support their conclusions and therefore enhance the validity of their findingsStudent generates a plan with their own ideas based on their experience and research. Controls and/or placebos are considered and the use of blind and double blind trials are evaluated.
Appropriately precise equipment is justified in its use and is used to make measurements over an appropriate range
All measurements are performed with accuracy and the methods used to acquire these are justified e.g. measure at eye level
A detailed, neat and complete table of results is built
Student conducts research into published data to support their conclusions and therefore enhance the validity of their findings (all references annotated correctly)
L3/4Comment by Martin Mullan: Comment by Sanngeeta Nadarajan: Comment by Sanngeeta Nadarajan: ii) Possible systematic errors and random errors in generating results are identified and explained.Student identifies a possible confounding variable and describes how it's effect can be reducedAll possible 'confounding' variables are identified and efforts described to reduce their effects (Random errors)All possible 'confounding' variables are identified and efforts described to reduce their effects (Random errors)
Systematic errors (e.g. zero error) are identified and how these can be reduced considered
CPresent and analyse data
L3/4Comment by Sanngeeta Nadarajan: i) Use appropriate methods to analyse results, present data and identify trends, patterns and/or observations.Inappropriate or incomplete graph drawn
Student makes use of: descriptive statistics e.g. mean
Student identifies relationships in graphic representation to identify patterns and relationships (eg correlation and cause)
Student uses the observed data to support their statementsAppropriate (bar chart for categoric data, histogram, line graph for continuous data) and complete graph (SLAPU'd) drawn
Student makes use of: descriptive statistics e.g. mean
Student identifies relationships in graphic representation to identify patterns and relationships (eg correlation and cause)
Basic subtraction mathematical operations are used to support observations
Student makes use of: descriptive statistics (mean, mode and median, error bars, standard deviation identification of outliers and range)
Mathematical operations are used to support observations e.g. % change and % difference
L4/5ii) Any apparent anomalies and inconsistencies are described, the methodology is evaluated and suggestions are made to improve or further the work of the investigation.Validity, Accuracy, Precision, Reliability (VAPR) are not fully evaluated or are incomplete/confused.
Student identifies outliers and/or anomalies but is unable to explain why they occur or how to improve the technique to reduce them next timeStudent attempts to evaluate the validity of inferences made from data in terms of the methods, techniques and processes (Validity, Accuracy, Precision, Reliability - VAPR) used to collect and analyse the data
Student attempts to explain why there is a lot of variability in their repeated measurements AND/OR identifies and attempts to explain outliers and anomalies in their measurements in an effort to reduce their effects in the futureStudent fully evaluates the validity of inferences made from data in terms of the methods, techniques and processes (Validity, Accuracy, Precision, Reliability - VAPR) used to collect and analyse the data, recognising any systematic or random errors present or conflicting evidence.
Student explains why there is a lot of variability in their repeated measurements and explains outliers and anomalies in their measurements in an effort to reduce their effects in the future
Student suggests extensions to the current investigation to acquire more data in similar contexts to support their conclusions e.g. effect of caffeine on the number of leg twitches in brine shrimp
Create a full write-up using the resources you have been given. Include: introduction and science, hypothesis, equipment, plan, safety, table of results, graph (table and graph should be hand-drawn and uploaded into your GDrive folder - Embed OR create a link to them in your write-up doc), analysis, conclusion, evaluation, references/bibliography Self Assessment
Use the rubric to remind yourself of what needs to be included.
Self assess yourself against the rubric and include the score at the end of your writeup. Use the commenting features to identify your point allocation.
Investigating the water-potential of potato cells
Osmosis Practical
Introduction to Osmosis: Comment by Martin Mullan:
Osmosis is known as the movement of water particles through a partially permeable membrane from an area of high concentration of water particles to an area of low concentration of water particles until equilibrium is reached. The purpose of this experiment is to investigate the movement of water in and out of plant cells. The plant cells chosen for this experiment is potato cells. Osmosis travels passively and therefore, doesnt require any energy. We had measured the mass of the potato before and after the experiment because the mass of the potato would have changed as osmosis occured, if the water particles had either move in or out of the potato cell. The aim for this experiment is to predict the water potential of the potatoes by seeing where the percentage change in mass of the potatoes before and after the experiment is 0%, which suggests that there isnt much movement from inside the potato to the outside or vice versa as the water potential inside the potato is equal to the water potential outside the potato. This is because water,at this particular concentration, enters and leaves the cell at the same rate. Thus, by knowing the concentration of salt where there is no percentage change, we can assume that that is the water potential of the potato as the concentration would be the same on both sides of the cell membrane. The percentage change would then be plotted in a graph to gage where the percentage is equal to 0%. The percentage change was plotted, rather than the actual mass before and after the experiment because the masses of the potato before they were placed into the salt solution is are all different and to achieve the exact mass for all the potato samples would have been time consuming and by doing so, the surface area of the potato could also be compromised, which would affect the results. Comment by Martin Mullan:
Ethical issues:
There were no ethical issues concerning this experiment as there were no tests on humans or animals that were involved.
Hypothesis :
I predict that if the potato was left in a solution that had a concentration that was higher than the potato itself, the mass of the potato would increase and if they had a similar water potential, there would be no change in mass of the potato. If the potato was left in a solution that had a lower concentration than the potato itself, then the mass of the potato would decrease.
Official Time Frame of Experiment :
Start time (time the potatoes were inserted into test tube with different solutions) : 17th of September 2014 : 10.53 a.m.End time (time of extraction of potatoes from solution) : 17th September 2014 : 11:13 am
Equipment Used:
25 ml Measuring Cylinder Cork Borers Tissue Paper18 Test Tubes Different concentrations of NaCl solution (0.1M, 0.2M, 0.3M, 0.4M, 0.5M) Distilled Water1 clear ruler1 stopwatch1 electronic balanceScalpelTongs
Plan:
The experiment was to test Osmosis on the potatoes by having them submerged in salt solutions of different concentration. Each potato was to be cut up to the same specific length ( the width of the potato was kept the same as we used the same borers to cut out the potato pieces) and have the mass measured and inserted into different test tubes that have the different concentrations of solutions in them. Then, we measured the mass of the potatoes after the experiment, and calculated the percentage change in mass and plotted a graph. The independent variable would be concentration of the salt solution and the dependent variable would be the mass of the potato after it has been extracted out of the salt solution. Variables such as the pH of the solution, the temperature of the salt solution, the type of potato (if possible - take all the potato samples from the same potato), the length of each potato (2 cm), time that the potato samples were left for; must be kept the same. This is because many of these variables can affect the rate of osmosis, which could affect our results. Besides, the temperature of the atmosphere and the humidity also affects the osmosis rate as an increase in humidity means there are more water molecules in the air, which means that there is a higher water concentration on the outside of the cell membrane, which reduces the rate of osmosis.The more detailed plan is as follows;Comment by Martin Mullan: Comment by Sanngeeta Nadarajan: Comment by Martin Mullan: Comment by Martin Mullan: Comment by Martin Mullan: Comment by Martin Mullan: Comment by Sanngeeta Nadarajan:
1. Label 6 boiling tubes; one with Distilled water and the rest with the other salt solutions of different concentrations. Then, add 25 ml of the solution into its respective tube. Label another 12 test tubes and repeat the same procedure as before. This basically means that there would be 3 test tubes with distilled water, 3 test tubes with the salt solution of 0.1M concentration and 3 test tubes with the salt solution of 0.2M concentration and so on. Make sure that the test tubes are labelled with the concentration of solution that it holds, with a smudge and water proof marker pen, correctly. This is to prevent any confusion later on. This ensures that the experiment is repeated and improves the reliability of the results as we take an average from the 3 results and cancels out the possibility of an outlier if the result differs hugely with the other 2 results (verifies the results). Again, by taking an average, it makes the results more reliable and identifies any anomalies. When pouring the salt solution, as the salt solution was in a conical flask, we poured the solution into a smaller beaker first (100 ml) and then poured it into the measuring cylinder, to measure the solution, which was then poured into the test tube. This was done to prevent any spillage of the salt solution that could cause some accidents if the other students had slipped on it. A 25 ml measuring cylinder was used because we were measuring exactly 25 ml of liquid. This was to ensure that, when measuring the solution to be poured into the test tube, it was as accurate and as precise as possible and to prevent any reading errors that could occur with a larger measuring cylinder (such as a 50ml measuring cylinder) as the scales would usually be bigger on a larger measuring cylinder. If we were to use a smaller measuring cylinder (10 ml), we would have to measure and pour the solution a couple of times, which could be time consuming. Also, to ensure that we get the most accurate and precise volume of salt solution as possible, we read the bottom of the meniscus. This happens when the water molecules are attracted to the sides of the container and therefore, we read from the bottom of the meniscus to reduce the possibility of measuring the wrong volume of solution. Comment by Martin Mullan: Comment by Martin Mullan: Comment by Martin Mullan: Comment by Martin Mullan:
2. Next, use the cork borer and cut the potato pieces from the potato itself. When cutting the potato, ensure that you are cutting away from your hand as the cork borers are quite sharp and you could possibly injure yourself while cutting into the potato. Cut the potato pieces into 2 cm of length using a scalpel. Also, when cutting with a scalpel, make sure that you are careful and do not cut yourself with the scalpel. The length has to be kept the same as the volume of the potato differs, which would affect the rate of osmosis. Also, the cork borers are used to cut the potato to ensure that the potato pieces have the same surface area. This is because a different surface area could also affect the rate of osmosis. Also, when cutting the potato pieces, ensure that the skin of the potato pieces is cut off as the skin of the potato is harder than the inside of the potato and this could affect the rate of osmosis by reducing the movement of water through it due to its hard cell wall. Comment by Martin Mullan: Comment by Martin Mullan: Comment by Martin Mullan:
3. Next, use a tissue paper and blot each of the cylindrical potato pieces to remove excess water, which could affect the mass of the potato pieces when measuring it. Make sure this is done quick and to prevent the tissues of the potato from drying out. As the tissues have dried out, this would also affect the rate of osmosis as there would be more absorption of water by the dry tissues and this would not portray the actual water potential of the potato, which would affect the accuracy of our results. You need to also act quick to prevent evaporation of water from the potato cells from happening, which could also reduce the water potential of the potato cells. Comment by Martin Mullan:
4. Next, carefully record the mass of each of the cylinder potato pieces. When using the balance, ensure that the balance starts off with 0.00g to prevent a miscalculation of the mass of each potato piece. This could be a systematic error which results in the masses of the potatoes bring greater than they actually are. When taking a reading from the balance, take at least 2 decimal places to ensure a more accurate result. This is because the potato pieces are so small that if one decimal place was used, then most of the masses of the potato pieces of before and after the experiment would be the same. (An example of this would be the actual result obtained; the mass before of one of the potato pieces was 0.73g and the mass after was 0.74g. If only one decimal place was taken, then both the masses of the potatoes would be 0.7g and that means there would be no percentage change in mass observed when in actual fact, there was a change in mass). Also, ensure that the balance is clean before using it to prevent any miscalculation of the masses by taking account of the extra masses of the dirt on the balance. Comment by Martin Mullan: Comment by Martin Mullan: Comment by Martin Mullan: Comment by Sanngeeta Nadarajan: Comment by Martin Mullan: 5. Next, transfer each potato piece into a respective test tube. Make sure it is known that which potato is placed in which test tube (check the label on the test tube) as they would all have different masses to prevent a miscalculation further on when the reading of the mass of the potato after the experiment is taken. Start a stopwatch as soon as the potatoes are transferred into the test tubes. Leave the potatoes for 20 minutes.
6. Put the test tubes into a test tube rack and place it into a water bath. This is to ensure that the temperature that all of the potatoes are facing is the same. This is done to eliminate the fact that different temperatures could affect the rate of osmosis by either speeding up the rate (when the temperature is high, the kinetic energy of the particles increase and they move faster, and thus the rate of osmosis increases) or slowing it down (when the temperature is low and the particles do not have as much kinetic energy, and move slower which slows down the rate of osmosis). If the temperature is too high, it could also denature the tissues which would lower the water potential of the potato. They are placed in a water bath to prevent the temperature of the environment and the surrounding from changing and affecting the temperature of the solutions in the test tube. Ensure the temperature of the water bath is an optimum temperature for the potatoes and not too hot or too cold. Ensuring the water is not too hot is also a safety precaution, to prevent scalding of a students hand when placing the test tube rack into the water bath. Comment by Martin Mullan: Comment by Martin Mullan: 7. After 20 minutes, use a tong to remove the potato pieces from the test tubes. Place them onto a tissue paper and blot them to remove excess water, which could affect the measuring of the mass of the potato pieces by adding a surplus weight. This then affects the accuracy of our results. Then, weigh the masses of the potatoes and record the mass into a table. Record the difference in masses in the table and work out the percentage change in mass of the potato pieces. This can be calculated by the change in mass divided by the initial mass multiplied by 100%. (Some numbers may be in negative but this is only because there has been a loss in mass) Comment by Martin Mullan: 8. Next, draw out a table and record all the results. Calculate the average results and plot them onto a graph with the y-axis labelled as percentage change in mass and the x-axis labelled as the different concentrations of salt solution (molarity of salt solution). Draw a line of best fit.
9. Find the concentration of solution when the percentage change in mass is 0%. This can be done by noting where the line of best fit crosses the x-axis. This can be predicted as the water potential of the potato as there was the same amount of movement of water that entered and left the cell.
Safety Measures:
As per every experiment, make sure that long hair is tied back, and all chairs are pushed under the table, to prevent anyone from tripping over the chairs. Also, make sure that safety glasses are worn to prevent any liquid from splashing into your eyes, even though none of them are acidic. As mentioned before, pour the salt solution into a beaker before pouring it into the measuring cylinder to prevent any spillage of the solution on the floor that could cause accidents. Besides that, also make sure that all chairs are pushed under the table to prevent any students from slipping and also make sure that there are no books or electrical items on the tables in which the experiment is conducted to prevent an electric shock if the water accidentally spills onto the electronic items and also to prevent the damage of books.Also, ensure that when cutting the potato cylinders, ensure that you are cutting away from your hand to prevent any injuries caused by the cork borers. The salt solution doesnt have to be handled as carefully as other acidic solutions as if it touches your hand, it wouldnt cause any immediate injuries. However, do not ingest the solution as it could be very concentrated and wash off immediately when the solution touches skin to prevent any unexpected injuries (such as the concentrated salt solution entering any wounds on skin). Handle the test tubes carefully to prevent them from falling and breaking, which could cause injuries if stepped on.
Table of Results: Comment by Martin Mullan: Comment by Sanngeeta Nadarajan: Comment by Martin Mullan: Comment by Martin Mullan: Comment by Sanngeeta Nadarajan:
Graph: Comment by Martin Mullan: Comment by Sanngeeta Nadarajan:
Analysis of graph: Comment by Martin Mullan: Comment by Sanngeeta Nadarajan: Comment by Sanngeeta Nadarajan: The mean of the results altogether is -8.49%. The anomaly in the graph is the result of the percentage of change in mass when the concentration of the salt solution is 0.1M as it doesnt fit the trend and it increases from the previous percentage of mass change, which differs with all the other results. This could be due to a systematic (the balance wasnt tared before using it). It could also be a because we didnt leave the potato for a longer period of time to allow osmosis to take place fully. Comment by Martin Mullan: Comment by Sanngeeta Nadarajan:
Analysis:Comment by Sanngeeta Nadarajan:
The results were reached by taking the change in mass divided by the initial mass, multiplied by 100%. Then, to produce an accurate result, we had taken the averages of the repeats we did ( the 3 test tubes for each concentration) and used that as our result when plotting the graph.
From the results, we can clearly see that the average percentage change in mass of the potato has decreased to a negative number as the concentration of salt solution increases. This shows that the results are in a negative correlation. When the number is a positive number, as exhibited by the Distilled Water and the salt solution of 0.1 M concentration, it shows that the potato had gained mass by 16.52% and 16.85% respectively, which suggests that the water molecules had travelled from the salt solution or distilled water (the outside of the cell membrane) and into the potato piece (the inside of the cell membrane). From this, we can predict that the potato pieces has a higher salt concentration and a lower water concentration than the solution it is immersed in. Comment by Martin Mullan: Comment by Martin Mullan: When the number is a negative, the opposite is concluded. This is exhibited by the results of 0.3M, 0.4M and 0.5M of salt solution. This shows that there has been a negative loss in mass of the potato, which results in a negative percentage change in mass. This suggests that the water molecules from inside the potato cell has left the cell and entered the solution in the test tube it was immersed in. This could only be because the water concentration outside the cell is lower than the water concentration inside the cell, which means that the water molecules would move out of the cell to enter the salt solutions to reach equilibrium. My results do match the initial prediction, with the prediction that if the concentration of the solution was higher than the concentration inside the cell, there would be a negative percentage change in mass as the the potato loses mass while trying to achieve equilibrium in concentration.
Conclusion : Comment by Sanngeeta Nadarajan:
After cross- referencing my results with other practicals, I can conclude that the water potential of potato 0.205 M. The graph also supports this statement as we can see that the line of best fit crosses the x-axis at this point. This suggests that the percentage change of mass is 0% and this can only be possible because the water potential on both sides of the membrane (the outer part - which is the salt solution, or the inner part - which is the potato cell) is equal which suggests that water enters and leaves the cell at the same rate. It also shows us that concentrations that were below that amount were lower than the concentration of the potato and concentrations that were higher than that amount was higher than the concentration of the potato. This is because when the concentration of the salt solution is lower than that of the potato cell, there are more water particles in the solution than there are in the cytoplasm of the cell. This then leads to the water particles in the cell to leave the cell and, through osmosis, cross the partially permeable membrane and mix with the solution on the other side of the cell membrane, to reach equilibrium (same concentration on both sides). Comment by Martin Mullan: Comment by Martin Mullan: Comment by Sanngeeta Nadarajan:
The graph is in a negative correlation and this is because as the concentration increases, the percentage change in mass decreases. And the higher the concentration, the more the water particles in the potato cells would have to leave the cell, in order to reach equilibrium, which leads to a higher decrease in mass.
According to http://faculty.clayton.edu/Portals/466/Content/BIOL%201107%20Labs/sample%20lab%20report%202.pdf , through their experiment, they had reached to the conclusion that the water potential of the potato was 0.283M. Even though this differs slightly to my results, they had also seen the general trend of the higher the concentration of the solution, the more the negative percentage change in mass and the lower the percentage. The reason why they have a different answer to the water potential could be due to the fact that they have conducted this experiment in a different region of the world, which could mean that the potatoes that they have experimented on is of a different type or species to the ones that were conducted for this experiment. The higher prediction they got for their result compared to mine, could suggest that they are in a region that has a higher humidity. This is because if they are in a region of higher humidity. then the potatoes would probably have a higher water potentialComment by Martin Mullan:
Evaluation: Comment by Sanngeeta Nadarajan: Comment by Martin Mullan: This experiment had helped us to gauge the water potential of potato cells. However, to further investigate the effects of osmosis in plant cells, we could use another type of plant cell, such as a turnip cell, to see if the effect of osmosis also applies to those cells. By repeating the experiment with another plant cell and receiving similar results, it would further validate the results of this experiment. Besides that, other experiments that are held in the same context can also be used to support our conclusion. An example of this would be to use sucrose solution instead of salt solution. However, it is possible that different types of potatoes have a different water potential. Therefore, to ensure that our results are reliable, it is best if we took all the potato samples from one type of potato. We also cannot say that the water potential of the potato that we had predicted from this experiment applies to all potatoes as different potatoes would have a different water and salt concentration, which would affect the rate of osmosis in a different way. Comment by Martin Mullan:
After we had taken out the potato pieces from the 0.2M solution, we realised that we had forgotten to peel off the skin of one side of 2 of the potato pieces. This would have affected the experiment as the rate of osmosis would have been affected and slowed down at the side where the peel wasnt cut off because the skin of the potato was hard and thus wouldnt have allowed the water molecules to pass through as effectively as the sides that did not have the potato peel on them. This meant that the validity and accuracy of the experiment has been interfered with and would not show an accurate result. Even though the skin is edible, it is hard due to many reasons, with one of them being for protection and another to stop there being much water loss from the inside of the potato. Due to the fact that we had not cut the skin of the potatoes that were in the 0.2M solution, the results were quite varied and was had ranged from -1.28% to 1.37%. Interestingly, it was the potato with the 1.37% and 0% and the change in mass that did not have the skin cut off. This further evaluates the statement that, if the skin wasnt cut off, it would be harder for the water molecules to pass through, which would decrease the rate of osmosis and maybe only allow osmosis to travel one way and only slightly in the other way. This might be an anomaly as the potato with the skin cut off was a negative percentage change in mass. Comment by Martin Mullan: Comment by Dafinah Azman: Comment by Sanngeeta Nadarajan: Comment by Martin Mullan:
We could have also repeated the experiment more than 3 times to ensure the reliability of the results and to identify any anomalies as with just 3 results, it is hard to conclude or see if there are any anomalies.
References/bibliography: Comment by Dafinah Azman: Comment by Sanngeeta Nadarajan:
http://dpbiologyiszl.wikispaces.com/file/view/Sample+Lab+Report-+Potato+Osmosis.pdf
http://www.123helpme.com/view.asp?id=122116
http://faculty.clayton.edu/Portals/466/Content/BIOL%201107%20Labs/sample%20lab%20report%202.pdf
MR MULLANComment by Sanngeeta Nadarajan: Comment by Martin Mullan: Comment by Sanngeeta Nadarajan:
Rubric rating submitted on: Mon Sep 29 2014 18:37:11 GMT-0400 (EDT) by [email protected]
AUse apparatus skilfully and safely
i) Apparatus and materials are handled correctly and safely and manipulative techniques are used in an appropriate and safe manner Your score: 4.5Personal safety precautions considered
Some care taken to follow safety procedures.
Appropriate techniques attempted.Some elements of risk involved in using equipment and chemicals is considered
Personal safety precautions considered
Investigation carried out safely with effort given to appropriate use of techniquesFull risk assessment in using equipment and chemicals is considered and safety precautions are prepared before investigation
Investigation carried out with safety as a priority.
All manipulative techniques used with skill
AUse apparatus skilfully and safely
ii) The practical work is carried out in an organised, methodical and safe manner, with due consideration of the well-being of living organisms and the environment. Your score: 0A brief comment on the ethical issues involved in the context of the investigationMost of the ethical issues involved in the context of the investigation are considered and evaluatedFull consideration of the ethical issues involved in the techniques with regards to humans and animals.
E.g. treatment of daphnia in caffeine investigation OR the social, moral and economic implications of using the antimicrobial properties of plants
B Produce and record reliable and valid results
i) Measurements and observations are made with precision and recorded in a structured manner; variables are identified and the validity and reliability of results are justified. Your score: 4.5Student follows teacher's plan
Independent and Dependent variables identified.
Appropriate equipment is used to make measurements over an inappropriate range
Most measurements are performed with accuracy but the methods used to acquire these are not justified e.g. measure at eye level
An appropriate number repeats are planned for but not completed
A table of results is built but has errors on decimal places and/or units and is disorganisedStudent follows teacher's plan and makes attempts to enhance the plan with their own ideas based on their experience and research.
Independent and Dependent variables identified.
Appropriately precise equipment is used to make measurements over an appropriate range
All measurements are performed with accuracy and the methods used to acquire these are justified e.g. measure at eye level
An appropriate number repeats are planned for and completed
A detailed, neat and complete table of results is built but has errors on decimal places and/or units
Student refers to published data to support their conclusions and therefore enhance the validity of their findingsStudent generates a plan with their own ideas based on their experience and research. Controls and/or placebos are considered and the use of blind and double blind trials are evaluated.
Independent and Dependent variables identified.
Appropriately precise equipment is justified in its use and is used to make measurements over an appropriate range
All measurements are performed with accuracy and the methods used to acquire these are justified e.g. measure at eye level
An appropriate number repeats are planned for and completed
A detailed, neat and complete table of results is built
Student conducts research into published data to support their conclusions and therefore enhance the validity of their findings (all references annotated correctly)
B Produce and record reliable and valid results
ii) Possible systematic errors and random errors in generating results are identified and explained. Your score: 5Student identifies a possible confounding variable and describes how it's effect can be reducedAll possible 'confounding' variables are identified and efforts described to reduce their effects (Random errors)All possible 'confounding' variables are identified and efforts described to reduce their effects (Random errors)
Systematic errors (e.g. zero error) are identified and how these can be reduced considered
CPresent and analyse data
i) Use appropriate methods to analyse results, present data and identify trends, patterns and/or observations. Your score: 3Inappropriate or incomplete graph drawn
Student makes use of: descriptive statistics e.g. mean
Student identifies relationships in graphic representation to identify patterns and relationships (eg correlation and cause)
Student uses the observed data to support their statementsAppropriate (bar chart for categoric data, histogram, line graph for continuous data) and complete graph (SLAPU'd) drawn
Student makes use of: descriptive statistics e.g. mean
Student identifies relationships in graphic representation to identify patterns and relationships (eg correlation and cause)
Basic subtraction mathematical operations are used to support observationsAppropriate and complete graph drawn
Student makes use of: descriptive statistics (mean, mode and median, error bars, standard deviation identification of outliers and range)
Student identifies relationships in graphic representation to identify patterns and relationships (eg correlation and cause)
Mathematical operations are used to support observations e.g. % change and % difference
CPresent and analyse data
ii) Any apparent anomalies and inconsistencies are described, the methodology is evaluated and suggestions are made to improve or further the work of the investigation. Your score: 3Validity, Accuracy, Precision, Reliability (VAPR) are not fully evaluated or are incomplete/confused.
Student identifies outliers and/or anomalies but is unable to explain why they occur or how to improve the technique to reduce them next timeStudent attempts to evaluate the validity of inferences made from data in terms of the methods, techniques and processes (Validity, Accuracy, Precision, Reliability - VAPR) used to collect and analyse the data
Student attempts to explain why there is a lot of variability in their repeated measurements AND/OR identifies and attempts to explain outliers and anomalies in their measurements in an effort to reduce their effects in the futureStudent fully evaluates the validity of inferences made from data in terms of the methods, techniques and processes (Validity, Accuracy, Precision, Reliability - VAPR) used to collect and analyse the data, recognising any systematic or random errors present or conflicting evidence.
Student explains why there is a lot of variability in their repeated measurements and explains outliers and anomalies in their measurements in an effort to reduce their effects in the future
Student suggests extensions to the current investigation to acquire more data in similar contexts to support their conclusions e.g. effect of caffeine on the number of leg twitches in brine shrimp
Self-assessment Your score: 5Basic pointsSome points are thoroughly evaluated and relate to the rubricThorough consideration of why the point has been awarded or not
Peer-assessment Your score: 0Basic pointsSome points are thoroughly evaluated and relate to the rubricThorough consideration of why the point has been awarded or not
Comments:Snageeta,Awesome first write-up; well done.Read my comments to see where you can tweak.Target: work on the analysis and evaluation.Cheers, MrM.
