7 most practical required

2.) Estimation of Osmoregularity in potato tissues

IB Biology Lab Potato Tissue

Aim: find the water potential of two different potato tissues, and discern which one has a higher osmotic potential.

Skills: making sample cores

Preparing solution concentrations

Collecting data

Analysing data to look for water potential.

Using the materials provided:

1) Make up a range of 5 solutions, of molarities 0, 0.1, 0.2, 0.3, 0.4, 0.5 or use 5 different concentrations of your choice (you must include 0)

2) At the same time, take 2 long samples of potato tissue and cut them into 6 sections of 2cm length each (you may need to take another core sample)

3) Prepare another 6 similar sections of the second type of potato

4) Weigh each of the potato cores, and place one of each type of potato next to each solution (ready to put them in).

5) Prepare a timer

6) Add the potato cores to the corresponding tubes at the same time.

7) You will need to time them for 40 minutes, before draining the liquid and re-weighing the potato cylinders. You will need to dry them with tissue paper, and weight them one at a time to avoid errors.

8) Calculate the % weight change of the potato cylinders at each molarity, and plot a graph.

Computer Tasks:

1) Hypothesise: which potato do you think will have a higher water

potential?

2) Define your variables

3) Prepare a suitable table for your results

4) plot the data using a scatter graph in excel (include a error bars for uncertainty and a trendline, and R2 value)

5) Identify where the trendline crosses the x-axis (this will be the approximate molarity of the potato tissue.

6) Using the table provided in the appendix, estimate the osmotic potential of the potato tissue

7) Make a conclusion, and an evaluation based on your results.

Molarity (mol dm) Osmotic potential kPa

0.05 -130

0.10 -260

0.15 -410

0.20 -540

0.25 -680

0.30 -860

0.35 -970

0.40 -1120

0.45 -1280

0.50 -1450

0.55 -1620

0.60 -1800

0.65 -1980

0.70 -2180

0.75 -2370

0.80 -2580

0.85 -2790

0.90 -3000

0.95 -3250

1.00 -3500

Table 4.1 Relationship between molarity and osmotic potential of sucrose solutions

4.) Separation of photosynthetic pigments using chromatography

5.) Attempting to create a sealed mesocosm

MESOCOSM PROJECT SENIORS

Mesocosm Project:

Goals:

Main goal: Create a living ecosystem in a jar. Study the behaviour of the ecosystem and try to learn something about the way the organisms interact with themselves and their environment.

· Curriculum goal: Design and implement mesocosms (mandatory IB project lab)

· Apply the following knowledge from ecology: Understand the sources, reservoirs and sinks of carbon dioxide in the carbon cycle topic 4.3

· Apply knowledge of trophic levels and feeding relationships topic 4.1

· Apply knowledge related to energy fluxes. Topic 4.2

General Advice-

Species you choose are up to you

-aquatic or terrestrial

Think about air, don't underestimate the power of air.

- Be careful with microbes, they can ruin an experiment. Try to design conditions which are not anaerobic, too warm or too humid.

-Up until week 4, you are allowed to make changes to your mesocosm and you may need to do so as new information comes to light.

Project rules

· The mesocosm has to include at least three trophic levels.

· Students may not work in groups of more than three.

Micro-Deliverables:

1. Week one an abiotic environment (habitat) and a carbon cycle plan (for your mesocosm)

2. Week two a, a sheet of calculations of productivity of your producers. A mesocosm with producers in it.

3. Week three A mesocosm with three trophic levels, a food chain and a

detailed diagram.

4. –Week four seal it and try to last for 4 days, if you ast for more than 4 days you get extra credit a mesocosm diary.

Micro deliverables are mandatory but not graded (pass / fail).

FINAL PROJECT DELIVERABLES

1. Mesocosm (sealed)

2. A guide to a mesocosm printed or e doc)

RECOMMENDED STEPS

1. Choose you habitat, aquatic vs terrestrial

2. Research your animals and know what they eat. Be aware of competition.

3. Start experimenting.

4. Keep a diary of your mesocosm.

5. Meet regularly to check on our mesocosm and make recommendations for changes.

6. Make adjustments to your mesocosm based on your observations. Try to fine tune your mesocom so it is ready for the big day (MESOCOSMS CLOSING DAY)

7. Make a note of interesting unresolved questions which may come to light in the process of your investigations. This will help you to become more thoughtful.

Rubric

Excelling: 3 Satisfactory: 2 Poor: 1

Knowledgable

3- Demonstrates knowledge of the unique role of each species in the ecosystem. Can make connections between the abiotic environment and the biotic community.

2- Demonstrates knowledge of the main role of each species. Can make one connection between the abiotic and biotic environment.

1- Demonstrates limited or incomplete knowledge of the role each species is playing in the ecosystem. Makes no connections between the abiotic and biotic environment.

Observations and data collection

3- Makes frequent, detailed and accurate observations to the changes happening in the mesocosm. Identifies long term trends.

2- Makes regular and careful observations of the changes happening in the mesocosm. Notices changes that occur.

1- Makes occasional observations on the changes happening in the mesocosm. May not notice changes that are occurring.

Responses based on ecological theory

3- Makes carefully considered changes to the mesocosm environment which link the observations made to appropriate scientific theory. Recognises that the decisions may be wrong and expresses doubt. Considers alternatives.

2- Makes changes to the mesocosm based on observations, and logical decisions. May not reference theory correctly. Doesn’t leave room for possible error in decision making. Chooses between more than one possible solution.

1- Changes the mesocosm arbitrarily, or applies theory incorrectly. Doesn’t recognize the uncertainty involved in decision making.

Mesocosm is successful

3- Mesocosm survives for more than four days.

2- Mesocosm lasts for four days

1- Mesocosm does not last for four days

6.) Monitoring of ventilation at rest and after vigorous exercise

7.) The use of potometers to measure transpiration