CIE IGCSE Biology Alternative to Practical

It definitely involved talking about dye, however, I think that the dye molecules would be too big to pass through the root cells. I'm not sure. I need some help .-. I regret not talking about boiling the potato as I don't think water is right instead of hydrogen peroxide. Welp, help.

Surely though you wouldn't put the roots in? The xylem would still soak up the water containing the dye even if the stem had horizontally been cut in half?


As for the control experiment I said to put the hydrogen peroxide on its own in the test-tube to ensure that it didn't decompose by itself. Think this is wrong though...


Posted from TSR Mobile

What plant was it talking about? For some reason, I'm pretty sure I thought a potted plant in soil and I talked about watering it and the dye would move up the xylem. I got some marks, I hope. It doesn't matter If you cut it as the xylem cells are dead it would still absorb the water as there is cohesion in the transpiration stream.
With relation to the control, I'm not sure, I knew it involved water, I wish I would've said replace the potato with water or something, someone let me know if water instead of hydrogen peroxide is right?

I felt it was easier than I thought it would be (looking at 2015's Summer paper, I thought it would be even harder), so I thought I messed up somewhere. Loads of people said it was easy, but some said it was horrible as well. I hope Chemistry and Physics are easier than last year's (and the specimens).

Nothing I actually revised was on it though. xD

I felt it was easier than I thought it would be (looking at 2015's Summer paper, I thought it would be even harder), so I thought I messed up somewhere. Loads of people said it was easy, but some said it was horrible as well. I hope Chemistry and Physics are easier than last year's (and the specimens).

Nothing I actually revised was on it though. xD

I'm fairly certain that for the control it was boiling potato to denature catalase as nothing else would give a definitive clear cut difference whereas dentures catalase= no bubbles. Replacing water with alcohol would only produce more bubbles but that doesn't allow you to reach a definite conclusion as in the question we could deduce alcohol did definitely have a effect since they used different concentrations in each and that produced different amount of bubbles

Also what did you guys put for the approximate bubbles with 50cm3 of alcohol I put 2 bubbles but I'm not sure that's right

I'm fairly certain that for the control it was boiling potato to denature catalase as nothing else would give a definitive clear cut difference whereas dentures catalase= no bubbles. Replacing water with alcohol would only produce more bubbles but that doesn't allow you to reach a definite conclusion as in the question we could deduce alcohol did definitely have a effect since they used different concentrations in each and that produced different amount of bubbles

Also what did you guys put for the approximate bubbles with 50cm3 of alcohol I put 2 bubbles but I'm not sure that's right

I'm fairly certain that for the control it was boiling potato to denature catalase as nothing else would give a definitive clear cut difference whereas dentures catalase= no bubbles. Rempving alcohol would only produce more bubbles but that doesn't allow you to reach a definite conclusion as in the question we could deduce alcohol did definitely have a effect since they used different concentrations in each and that produced different amount of bubbles

Also what did you guys put for the approximate bubbles with 50cm3 of alcohol I put 2 bubbles but I'm not sure that's right

I'm fairly certain that for the control it was boiling potato to denature catalase as nothing else would give a definitive clear cut difference whereas dentures catalase= no bubbles. Rempving alcohol would only produce more bubbles but that doesn't allow you to reach a definite conclusion as in the question we could deduce alcohol did definitely have a effect since they used different concentrations in each and that produced different amount of bubbles

Also what did you guys put for the approximate bubbles with 50cm3 of alcohol I put 2 bubbles but I'm not sure that's right

How can it be 0 though becuase there's no information in the question that allows you to draw the conclusion that ethanol concentration of 50% or over would completely kill catalase surely shouldnt it just be 1-2 bubbles produced

I'm fairly certain that for the control it was boiling potato to denature catalase as nothing else would give a definitive clear cut difference whereas dentures catalase= no bubbles. Rempving alcohol would only produce more bubbles but that doesn't allow you to reach a definite conclusion as in the question we could deduce alcohol did definitely have a effect since they used different concentrations in each and that produced different amount of bubbles

Also what did you guys put for the approximate bubbles with 50cm3 of alcohol I put 2 bubbles but I'm not sure that's right

It was 0, the concentration of alcohol is too high, I think. Hydrogen peroxide is the substrate, tbh I don't know If I would get marks for saying to replace it with water.

Guys, listen for the control experiment the answer could have been to substitute a test tube of hydrogen peroxide for a test tube of water. In fact it is the preferred answer!!!

The test was for the number of bubbles in H2O2, if you substituted it for water, there wouldn't be any gas given off as no decomposition would take place.

The test was for the number of bubbles in H2O2, if you substituted it for water, there wouldn't be any gas given off as no decomposition would take place.

I think that was the point of the control to show that you do need h2o2