right so get a load of seeds put them on cotton wool, each day take 3ish put in them oven, and weigh them to see the dry mass. add up the masses and divide by 3 to find the mean weight.
how long to leave them in the oven?? 1hour 2 hours?
how long to keep testing them a week or longer??
where to get background knowledge from??
jesus this is a mission
Turn on thread page Beta
BIOLOGY COURSEWORK - plez help watch
- 14-05-2003 11:40
- 15-05-2003 16:07
I know that the dry mass of the seeds decrease because they are respiring, it already basically tells you that in the planning excercise exam sheet. What I still can't figure out is WHY there would be a difference between the two species. This is a very complex practical to be set, too many variables I think. I mean one species may germinate faster than the other because they are genetically different therefore using food reserves faster, also the size of the seed, the size of the seedling AARRRRRRRRGGGGGGHHHH!!!!!!!!
Why would one use food reserves faster?
This is killing me!
- 15-05-2003 18:52
here's some stuff i found on the net, hope it helps!
You need seeds that will germinate quickly, one of which stores carbohydrate (starch) and the other which stores fat.
Suitable starch-containg seeds would be mung beans or broad beans Suitable fat-containing seeds would be sunflower or castor oil
You will have to 'plant' several batches of (weighed) seeds of each type. You don't need to record the weight of individual seeds, just the weight of the whole batch. At your set times, you should remove any seedling growth from a batch of seeds, and dry them in an oven at about 80°C until they stop losing weight. This final weight is the dry mass.
The following web site has basic information you could include, http://www.seaweed.ie/firstyears/germination.html
I gather (because other people have asked me about this investigation) that the idea is to test two seeds which store different types of food - carbohydrate and fat. You might expect fat stores to be used more slowly than carbohydrate stores because fat contains more energy per gram than carbohydrate. You could perhaps include, in terms of scientific knowledge, how carbohydrate and fat are metabolised in respiration.
To make this a fair, accurate and reliable test, you need to use lots of seeds. I would suggest at least 10 seeds for each time interval you choose. Using a large number improves accuracy of your averages. To make it fair, you need to express the weight loss as % weight loss (i.e. % weight loss is the unit) as the seeds cannot possibly all be the same weight initially.
only other stuff that i can say is that the seeds utilise their energy reserves at different speeds not only because of the way they store their energy, but also there are different methods of germination. Such as epigeal germination and hypogeal germination. You'll need to discuss this in the plan.
hope this helps! good luck everyone!
- 15-05-2003 19:04
what u mean y would there be a difference?? cause they r different species.......... hmmm ne way one other thing is you have to carry out the experiment in the dark so photosynthesis doesnt happen otherwise the dry mass would increase.
these r just some random notes below:
light - dark room
soil - inert - pertle / vermilite
water - 5mm3 (just random amount) added each time seeds are removed. use distilited water so less risk of contamination
heat - room temp (20oc)
a destructive method - not putting seeds back in
Early stage ends as soon as photosynthesis begins
both seeds much be dicolyledoneae eg Wheat / broad bean
some 1 help cause i only know some basic stuff
- 15-05-2003 19:12
the seeds should not be germinated in soil, they should germinate on wet cotton wool. also we were told not to calculate the percentage weight loss as it is not accurate enough.
- 15-05-2003 22:00
Cheers for replies!
Don't use compost it is just another bloody variable to worry about, use damp cotton wool (no inorganic ion levels etc to worry about etc). I don't see why percent loss of dry weight wouldn't be accurate enough? I was just going to weigh the whole batch and plot graph showing dry mass decrease against time.
- 17-05-2003 20:38
K guys its not that hard!
you have to do a dry mass measurement (using on oven and scales) every 24hrs are so...to see if all the water has been removed and then you can weigh it to see if the dry mass is increasing or decreasing - decreasing = respiration, increasing = photosynthesis. The RQ values has to do with the substrate inside each cell...ie if the RQ value is above 1 then the cell is mainly carbohydrate, 0.7 = lipid etc. to measure RQ use a respirometer (including soda lime to absorb CO2)
Hope this all kinda mkaes sense? if you want anything else get back to me!
if anyone has anyidea about what might be coming up on the practical exam???THIS TUESDAY??? it should be linked to the planning....respiration? photosynthesis would surely be too hard to investigate under timed conditions??
- 17-05-2003 20:43
carobohydrate seed = broad bean
lipid seed = maize
bit of both = cereals - ie barley, wheat
hope this helps someone along the way!
o - you dont need to worry about % dry mass, remember its just PLANNING! just use the results you get (from preliminary experiment maybe?) and see what happens - you dont nned to say exactly what happens remember?!just suggest!
youll all be fine im sure! just keep smiling!
- 17-05-2003 20:46
the different seeds respire at different rates becasue of the different substrate makeup - IE if it is carbohydrate then this takes a certain amount of time to metobollically break down, if its lipids it takes a different amount of time. so the main difference (part 2 of the investiagtaion) is becasue of the different food reserves / substartes - does that make sense!
DONT FORGET A BIBLIOGRAPHY!
- 18-05-2003 11:48
Does anyone know whether hypogeal or epigeal germination loses the most weight and why. Tried looking on the net and cant find nething.
- 18-05-2003 12:05
how hard is this! i cant help any1 with the planning but keep smilin and good luck on tuesday!
- 18-05-2003 12:26
right i understand the different germination types and all that stuff. wat i dont completely understand is the comparison of the two seeds??? what are we supposed to chose as differences between seeds. we supposed to use one fat seed, compaired with one carbohydrate seed. or one hypogeal seed compaired with the other type. or ............................
- 18-05-2003 14:23
You're supposed to use a calorimeter
- 18-05-2003 20:19
[QUOTE]Originally posted by MOLLY
does anybody know what apparatus are used?
- 18-05-2003 20:37
who knows how to conduct the practical on seeds?
- 19-05-2003 13:18
in answer to anna about what the pratical might be about i think it could be yeast/respiration etc. not quite sure but something like that.
- 19-05-2003 19:11
im sure itz going 2 b on mitosis/meiosis
- 19-05-2003 20:09
in our practice practical we just had to experiment with keeping 5 samples of water at different temperatures from 10-70 degrees and one of them had to be 35 degrees.
so testing the affect of concentration on the rate of enzyme reaction methinks?
- 19-05-2003 20:31
I know its last minute but can somebody help me with the coursework on seed germination. I keep arguing with myself over it. What kind of graph and I looking to plot? And the dry mass thing - how am I weighing different batches of seeds. and how long does the average seed take to germinate? I mean, I was going to take 5 seeds of each species every 24 hours, but what if by 48hrs they've got shoots? There'll be nothing to compare. And if i say I could check it more times it would be completely inpractical. And, if I'm doing the experiment in the dark - - - how will I see what I'm doing? And do I really have to go into RQ a lot?
- 19-05-2003 22:09
HI! i have to hand it in tomorrow and i am doing it now!! last min eh!!! just thought id say hello! cos i think i get it seems none of u had the idea to do food tests though. i did cos loads of othersdid at college but im not sure how they fit in . something to do with determining the reasons i think. any wasy tis a bit late now!
scales are good for the dry mass and leave it in an oven for 24hrs tis sufficient. then weigh them. then: work ou change in dry mass per day:
but as i sed tis a bit l8 noW! gotta go do it! c u all