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Effect of Temperature on the movement of pigment (anthocyanin) through cells membranes

It is difficult to judge some of this when I cannot see the actual results. In general, your explanations are not very clear. I would try reading this to someone who doesn't know what you've actually done in the experiment, and see if they understand it! I don't think they will. The introduction needs some work. There are some grammatical errors (you switch between singular and plural when referring to phosopholipids). A lot of the introduction is not relevant to this experiment - all you really need is the general structure of the membrane, the fact that it is fluid and the important role of the protein channels. Cholesterol has nothing to do with this experiment, for instance. In the last parargraph, you talk about light transmission without any explanation about how this relates to the experiment. Why no hypothesis? A lot of your 'interpretation' is just a detailed description of the results. This can be seen from a graph (in fact, that's the whole point of a graph!). It is very difficult to follow without looking at the graph. You need to simplify this description. I'm not really sure what you're doing - I assume that you're measuring the fluid around the beetroot with a colorimeter, but in that case an increase in transmission would mean that the solution was getting paler, whereas your account it would seem that, when you refer to an increase in transmission, the solution is getting darker (i.e. more leakage). Colorimeters also measure absorption - maybe that's what you measured? You see what I mean about this account being confusing - details of the method are really needed for clarity.Your evaluation is a bit superficial. Scientists evaluate RESULTS. I don't have your results, but is there anything about them that suggests that the method gave inaccurate results or was unreliable in some way. If so, you need to explain and suggest improvements. If not, then everything is fine and you don't need to suggest how possible mistakes may have occurred if the evidence is clear that they didn't!
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Beetroot core practical

"A nuymber of things need sorting here. The way your hypothesis is phrased is poor English and does not make sense ("the more colour will absorb" is meaningless). Your hypothesis is that the stronger the concentration of ethanol, the more pigment will leak out of the cells and into the solution. You should also explain WHY that is your hypothesis - what science backs it up?

Method, point 5: you say

"We then zeroed the colorimeter with the distilled water, and used a cuvette to measure the absorption of the liquid". The CUVETTE doesn't measure the absorbance, the colorimeter does. It would also be better to say "to measure the absorbance of light by the liquid".

 

Whgen discussing errors, you need to only consider those where you have some actual evidence that they occured (by looking at your results).

Your table is not clear (what do the numbers 1-9 refer to? Repeats? If so, your results seem very variable and quite unreliable.

Your conclusion and discussion lack detail. HOW does ethanol damage the membrane, for instance?

A lot of work seen at AS level is too 'wordy' but in your case the reverse is true - you need to put more detail and explanation in to convince the reader that you understand what is going on.

 

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How the surface area of a leaf affects the rate of transpiration.

OK but it is a POTOMETER not a photometer. Also,I think you underestimate the variability of living things - I don't think you really have any 'anomolous' results! Given this variability, an improvement would be to repeat much more. In a real research situation, this experiment would probably be repeated 50 times!

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Biology essay - daphnia experiment

A couple of points to make.

You keep mentioning the Daphnia getting 'stressed'. They have a VERY simple brain and I think it is highly unlikely that they can suffer from stress in the human sense.

There is no reason why pond water should be higher in oxygen than distilled water.

Again, the idea of Daphnia "feeling like they are in the right environment" attributes human senses/feelings to them.

There are a couple of faults / omissions in your method. Your Daphnia are going to have different resting heart rates (probably). Therefore, you will have to record the increase (if there is an increase) as % increase not absolute increase. You should allow the Daphnia a few minutes for their heart rate to stabilise before any count as the transfer to the slide or any change in conditions can affect heart rate. Why are you only counting for 15 seconds and multiplying by 4? If you can count for 60 (or even 30) seconds, it would be more accurate.

Your procedure lacks detail. How are you going to keep ther Daphnia still so that you can actually count the heart rate?

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Plan Effect of Windspeed on Transpiration

Generally, OK. It is not usual to talk about water potential when you are dealing with air rather than a solution. It is better just to talk about the concentration of the water.

You say that you will keep the temperature constant but you can't! You are blowing cold air onto the plant, which is going to cool it off! The temperature of the air in the room is not very relevant. Remmeber, too, that evcaporation from the surface of the leaf cools the surface, and the more evaporation, the more cooling.There is nothing you can do about this, you simply need to show that you are aware of it in your evaluation at the end. You must also take it into account - if the differences you get are small, you cannot say that the effect is down to wind speed, it could be temperature. If the difference is large, then it is most likely that wind speed is important (but part of the effect may still be due to temperature).

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osmosis (this is what i submitted for exam board, hand drawn graph was inc also)

I cannot give an actual mark for this (I don't know which board), only a grade.

Generally this is Ok but a few points:

In your hypothesis you impy that diffusion of water is one way. Something you say later implies that you know it is two way and that it is NET movement you are talking about, but I think you ought to make this clear.

Contamination of the potato by dirt etc. would have absolutely no effect on the results and is not worth mentioning (as it implies that you think it WILL have an effect, and this shows a lack of understanding).

In your hypothesis, you say "If the water potential of the potato is equal to that of the sucrose solution, there will be a net movement of water. The flow of water into and out of the potato is balanced." This should read "there will be NO net movement of water"

In your evaluation, you would EXPECT the potatoes to be slightly different weights, even if they were the same size - density is not consistent. That is why you measure % change in mass not change in mass.

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planning coursework

This is fine, except that you have not filled in the 'fair testing' table
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To investigate one factor that is likely to affect the activity of the enzyme Catalase in potato.

This is fine except for a couple of points. You identify that both temperature and pH affect enzyme reactions yet you make no attempt to either contol them or take account of their possible effect.
Also, you say your results support your hypothessis, yet that stated that the effect would level off when enzyme conc became limiting, yet your results don't show that - this needs to be explained
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Issue Report

I presume this is a 'work in progress' as it appears unfinished (my download consisted of 3 pages), but so far it is excellent and requires no alteration
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Method

This is fine, except don't call it 0% hydrogen peroxide....it's water!!!
  201 uploaded works
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Plant Fibre Results?

Contributors:
lilly

Difficulty: Easy | Reward: 2 SZPoints

Status: Unanswered | Comments: 1

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Plant Fibres

January 7, 2010 | AS Level Biology Revision
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Difficulty: Average | Reward: 3 SZPoints

Status: Unanswered | Comments: 0

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osmosis

November 7, 2009 | AS Level Biology Advice
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Difficulty: Average | Reward: 3 SZPoints

Status: Unanswered | Comments: 0

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An overly difficult practical to find!

Contributors:
Adefunke malak

Difficulty: Hard | Reward: 6 SZPoints

Status: Unanswered | Comments: 2

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osmosis and diffusion!!!!!!!!

December 3, 2010 | AS Level Biology Revision
Contributors:
Saba malak

Difficulty: Average | Reward: 3 SZPoints

Status: Answered | Comments: 2

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osmosis

February 6, 2008 | AS Level Biology Coursework
Contributors:
David elaine

Difficulty: Average | Reward: 3 SZPoints

Status: Answered | Comments: 2

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Transport across cell membranes

February 5, 2008 | AS Level Biology Coursework
Contributors:
lilly

Difficulty: Average | Reward: 3 SZPoints

Status: Answered | Comments: 1

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Human Biology coursework

December 27, 2007 | AS Level Biology Coursework
Contributors:
ramon

Difficulty: Hard | Reward: 6 SZPoints

Status: Answered | Comments: 1