.

[akira88]

I have another Biology SAC coming up, on enzymes this time.
We have to put liver in various  pH solutions, and then hydrogen peroxide in various pH solutions.We then graph the "height in bubbles" of the oxygen produced in the test tubes...
Hmmm...

I did that exact SAC.

Omg if you did can you help me? The method my teacher wrote out makes NO sense, and it's tomorrow :S
Apparently you get 5 test tubes, place hydrogen peroxide in each, and then various pH solutions of 1,4,7,9 and 14 into each one. Record "height of bubbles". It's meant to be recording the effect of the enzyme catalase (which breaks down hydrogen peroxide into water and oxygen), but I am confused as there is no catalase IN the pH solution OR the hydrogen peroxide, so how on earth am I meant to measure the "bubbles" caused by the release in oxygen? o.o
With 5 more test tubes, I am meant to put liver in each, and then the various pH solutions again. Measure "bubbles" again. This also doesn't make sense, there isn't any hydrogen peroxide so how am I meant to measure the effect of the enzyme catalase? Sorry if I'm not clear here, if someone replies I will actually get out my sheet and retype it.
Any help please?

[shinny]

I have another Biology SAC coming up, on enzymes this time.
We have to put liver in various  pH solutions, and then hydrogen peroxide in various pH solutions.We then graph the "height in bubbles" of the oxygen produced in the test tubes...
Hmmm...

I did that exact SAC.

Omg if you did can you help me? The method my teacher wrote out makes NO sense, and it's tomorrow :S
Apparently you get 5 test tubes, place hydrogen peroxide in each, and then various pH solutions of 1,4,7,9 and 14 into each one. Record "height of bubbles". It's meant to be recording the effect of the enzyme catalase (which breaks down hydrogen peroxide into water and oxygen), but I am confused as there is no catalase IN the pH solution OR the hydrogen peroxide, so how on earth am I meant to measure the "bubbles" caused by the release in oxygen? o.o
With 5 more test tubes, I am meant to put liver in each, and then the various pH solutions again. Measure "bubbles" again. This also doesn't make sense, there isn't any hydrogen peroxide so how am I meant to measure the effect of the enzyme catalase? Sorry if I'm not clear here, if someone replies I will actually get out my sheet and retype it.
Any help please?

The first set of 5 test tubes are controls. They don't have any catalase in them in case the breaking down of hydrogen peroxide occurs without the presence of catalase anyway (and I think it does, albeit at a negligible rate - hence the need for the enzyme). You won't see any bubbles. For the second set, I'm not sure if it's a typo or if you misread the prac instructions, but there should be hydrogen peroxide in each set of test tubes unless that's another control of some sort and then there's another set of test tubes.

EDIT: Basically what should be happening is that the controls (hydrogen peroxide+pH solution) produce no bubbles, and then the experimental tubes (hydrogen peroxide+pH solution+liver which has catalase in it) will produce some. However, as the liver is around pH 7 and typically enzymes function at their maximum rate at the pH from where they're found, I'd assume that the bubbles would be produced fastest in the pH 7 tube, with the rate decreasing as you get further away from this from either side. So keep in mind that with this experimental design, you're not really measuring the effect of the enzyme catalase as you said; you're measuring the effect of pH on enzyme function.

[akira88]

I have another Biology SAC coming up, on enzymes this time.
We have to put liver in various  pH solutions, and then hydrogen peroxide in various pH solutions.We then graph the "height in bubbles" of the oxygen produced in the test tubes...
Hmmm...

I did that exact SAC.

Omg if you did can you help me? The method my teacher wrote out makes NO sense, and it's tomorrow :S
Apparently you get 5 test tubes, place hydrogen peroxide in each, and then various pH solutions of 1,4,7,9 and 14 into each one. Record "height of bubbles". It's meant to be recording the effect of the enzyme catalase (which breaks down hydrogen peroxide into water and oxygen), but I am confused as there is no catalase IN the pH solution OR the hydrogen peroxide, so how on earth am I meant to measure the "bubbles" caused by the release in oxygen? o.o
With 5 more test tubes, I am meant to put liver in each, and then the various pH solutions again. Measure "bubbles" again. This also doesn't make sense, there isn't any hydrogen peroxide so how am I meant to measure the effect of the enzyme catalase? Sorry if I'm not clear here, if someone replies I will actually get out my sheet and retype it.
Any help please?

The first set of 5 test tubes are controls. They don't have any catalase in them in case the breaking down of hydrogen peroxide occurs without the presence of catalase anyway (and I think it does, albeit at a negligible rate - hence the need for the enzyme). You won't see any bubbles. For the second set, I'm not sure if it's a typo or if you misread the prac instructions, but there should be hydrogen peroxide in each set of test tubes unless that's another control of some sort and then there's another set of test tubes.

EDIT: Basically what should be happening is that the controls (hydrogen peroxide+pH solution) produce no bubbles, and then the experimental tubes (hydrogen peroxide+pH solution+liver which has catalase in it) will produce some. However, as the liver is around pH 7 and typically enzymes function at their maximum rate at the pH from where they're found, I'd assume that the bubbles would be produced fastest in the pH 7 tube, with the rate decreasing as you get further away from this from either side. So keep in mind that with this experimental design, you're not really measuring the effect of the enzyme catalase as you said; you're measuring the effect of pH on enzyme function.

Hey thanks a lot for that, but no there is no typo, the method specifically says just to put liver and pH solution into the test tube, and no hydrogen peroxide which was why I was confused. It was a prac my teacher wrote up herself which was why I am wary (as she is prone to a lot of mistakes..)
But thank you again!

[TrueLight]

wth yeah i dont think it makes sense... u need liver (this contains the catalase right? or u adding seperate?) and hydrogen peroxide...

[akira88]

wth yeah i dont think it makes sense... u need liver (this contains the catalase right? or u adding seperate?) and hydrogen peroxide...

Yeah the stupid teacher didn't put it on the sheet I'm hoping the SAC to be easy because it's on enzymes

[akira88]

Haha thanks for the tip!

[akira88]

Hmm I didn't really know that those inhibitors were called competitive and non-competitive, but I've heard of them before.. what textbook did you use last year?

[akira88]

Haha Andrew Douch. I use Heinemann, they really need to update the biology textbooks, they're getting old

[matty.k]

got my results back for my sac 25/30 cant say im to happy with that but hey most of the class failed.

[akira88]

got my results back for my sac 25/30 cant say im to happy with that but hey most of the class failed.

Good shit man - it's the rank which is what you're after remember .

Trueee.

I got my SAC back 24.5/25, lol lost the .5 of a mark because I described that the graph (that I had in my results) revealed a bell-shape curve. I think I lost the marks for not mentioning the variables haha

[akira88]

Hmm I'm not sure what rank, but probably in the top 3

It was strange last year, my 2 friends did biology, one did better on his SACs than my other friend, and also performed a whole grade better in his two exams than her. Strange thing is, she got A+ for her SACs (girl with lower exam mark and sac mark) and the guy got A for his SACs (despite higher ranking and exam mark). Error of the VCAA? Or could there be another explanation?

[m@tty]

Hmm I'm not sure what rank, but probably in the top 3

It was strange last year, my 2 friends did biology, one did better on his SACs than my other friend, and also performed a whole grade better in his two exams than her. Strange thing is, she got A+ for her SACs (girl with lower exam mark and sac mark) and the guy got A for his SACs (despite higher ranking and exam mark). Error of the VCAA? Or could there be another explanation?

Are you sure that he had a higher ranking? If so, I have no explanation; from what I've read higher ranking=higher moderated mark.

[stonecold]

i doubt that is the case, because statistical moderation does not change the ranking of students in a cohort, only the grades.

highest ranking = highest sac mark

[akira88]

I know which is odd, he didn't have the highest ranking but he was probably in the top 3. Unless there was a really close margin of the rankings between him and my other, but I agree with you m@tty and stonecold, it really doesn't make any sense.

[slothpomba]

My class isnt doing fantastic... well the people that sit within a table of me that ive asked anyway