Loului

There is already a thread in general biology open on this subject - started by Angel; there is loads of information there

Oh yes Emily, water potential...*regrets having already handed coursework in* I knew those teachers were telling us all this stuff beforehand for a reason! Oh well....good luck to everyone else with their plan and also thanks to Angel for creating this board; it helped me too

Hee Hee! I like being a legend, thanks! (Rakuenso, was that an insult to me? Do you think i'm that sad?) Anyway... start with the prediction of what you think will happen and back it up with scientific knowledge. You don't really need any preliminary results, you just have to state how your preliminary work helped you decide things you would alter for your final method. I have just found a website that may help people really struggling: http://www.chadevans.co.uk/asite/Alevel/biology/pracfile/prac13.html In my plan I used acetic orcein, but there is also some blue stain you can use...which I have forgotten the name of - sorry! It should be on your coursework front cover sheet, I handed mine in on tuesday though. Also, it takes no longer than 48 hours for roots to grow, meaning that mitosis is occuring (anything that grows is undergoing mitosis). Finally, I don't think anyone has done the OCR practical AS level biology exam yet as it is a board timetabled thing - to prevent cheating such as this. I really hope this helps, good luck everyone

0.25 grams is the optimum amount of phosphate for plant growth - if you are given a complete nutrient solution then that is how much calcium dihydrogen phosphate there would be per dm3. During my preliminary work I grew five cloves of garlic in different phosphate concentrations. I measured the length of the longest root on each clove at several intervals then, after about a week, tested the 'root tip squash' preparation and looked under the microscope at some of the roots. I found that it is around 0.20 grams (from my cloves, these results may be due to the mass of each clove as this variable was not controlled for my preliminary working) of phosphate which encourages more cell division in the root tips. A higher concentration than 0.25 grams did inhibit the growth and I posted scientific knowledge earlier to back this up.

Control - no phosphate in the nutrient solution (to prove that is phosphate causing the cells to undergo mitosis and no other external factor) Dependant (what you are manipulating) - concentration of phosphate Independant (what you are measuring) - amount of mitosis occuring in the root tips Surely you can work out a prediction and some concentrations from the preliminary work I outlined in an earlier message? Remember all the work we do actually has to be our own, we're just here to help each other out

Oooooh, I have found stuff to answer my own question and I thought it may benefit some of you too. "Phosphorus (P) is an essential element classified as a macronutrient because of the relatively large amounts of P required by plants. Phosphorus is one of the three nutrients generally added to soils in fertilizers. One of the main roles of P in living organisms is in the transfer of energy. Organic compounds that contain P are used to transfer energy from one reaction to drive another reaction within cells. Adequate P availability for plants stimulates early plant growth and hastens maturity. Although P is essential for plant growth, mismanagement of soil P can pose a threat to water quality. The concentration of P is usually sufficiently low in fresh water so that algae growth is limited. When lakes and rivers are polluted with P, excessive growth of algae often results. High levels of algae reduce water clarity and can lead to decreases in available dissolved oxygen as the algae decays, conditions that can be very detrimental to game fish populations." from http://www.extension.umn.edu/distribution/cropsystems/DC6795.html "Phosphorus stimulates root growth and flowering in plants and is needed for energy transfer reactions in plant cells. Shallow rooted plants, such as carrots, onions, and radishes need more phosphorus than deep rooted plants such as corn, beans or peas. The optimum amount for your soil will in part depend on the crops that you grow. ... Excessive phosphorus will not be detrimental to plant growth. However, adding more phosphate either from fertilizer blends or organic sources will not benefit crops and may contribute to environmental degradation." from http://www.ipcm.wisc.edu/wcm/pdfs/1998/wcm98-25.pdf I can't find a straight answer on what we're doing though and I can't really find anything else that supports the fact that root growth is inhibited in higher concentrations of phosphate; this fact is correct though as everyone in my class has come up with these same results and my teacher has confirmed them

Which page is it in the biology 1 book? I'm not sure I can find it =( Anyway, from my preliminary work I have found that the optimum amount of phosphate is around 0.25 grams per dm3 of nutrient solution and that a concentration any higher than this inhibits the growth. The only problem is....i'm not sure why!!