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October 22, 2025, 10:13:03 pm

Author Topic: 2010 biology unit three exam  (Read 31203 times)  Share 

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simpak

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Re: 2010 biology unit three exam
« Reply #90 on: June 13, 2010, 01:23:59 pm »
... june 09:
Following is an example of a suitable set up.
• Take two groups of tomato plants that are the same age type and state of health. One group is affected with
beet caterpillars, the other is unaffected.
• Both groups are kept in the same environment (for example, the same temperature and water availability).
• Wasps are released and their activity is observed.
• Large numbers of plants are used or the experiment is repeated many times.

No a large sample is a different mark to a repeated measures experiment.
^^same mark

why would u repeat it under diferent conditions?? that will get u results all over the place when we are after clarity??

Oh okay it probably will be the same mark then!
However, they're not the same thing.
You would repeat it under different conditions because you want to ensure that no extraneous variables which were present at that time influenced results.
Like, temperature in a cold winter month leading to a faster metabolism, in this case.
Or something along those lines.

Large sample size is to rule out most extraneous variables to do with the mice.  I would say repetition is tackling more environmental extraneous variables.
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lexitu

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Re: 2010 biology unit three exam
« Reply #91 on: June 13, 2010, 01:28:37 pm »
This is from VCAA '06:

the number of mice in each group. It was preferable for students to state a specific number (of reasonable
magnitude) in each group, instead of simply describing a ‘large’ group. If no mention was made of the size of
the group, then the idea of replication of the experiment needed to be mentioned

mikee65

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Re: 2010 biology unit three exam
« Reply #92 on: June 13, 2010, 04:41:48 pm »
Quote for the red and blue light:
I picked blue light because I reasoned that water would
distort the frequency wavelength of light, making it closer
to the colour blue than red, and because plants generally
photosynthesize well with red *and* blue (I was never told
which one was better), I thought blue based on that reasoning.
(I also had some stupid support logic that helped a little: "oh, water
is blue so when light goes through it, the light turns blue too!")

Water is actually colourless. The blue in the ocean we see is due to other reasons (was it actually the sky? I vaguely remember someone saying that explanation was wrong). Anyway, I don't remember what's taught in VCE, but Wiki says chlorophyll absorbs blue the most. And we all know Wiki is always right.
shinny i put down red, do you think they will accept both? or only blue?

stonecold

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Re: 2010 biology unit three exam
« Reply #93 on: June 13, 2010, 04:43:34 pm »
no one knows mikee.  they put that question in there on purpose.  it's not like it was an accident so IMO it looks like they have their eyes set on a particular answer.
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shinny

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Re: 2010 biology unit three exam
« Reply #94 on: June 13, 2010, 04:51:00 pm »
Quote for the red and blue light:
I picked blue light because I reasoned that water would
distort the frequency wavelength of light, making it closer
to the colour blue than red, and because plants generally
photosynthesize well with red *and* blue (I was never told
which one was better), I thought blue based on that reasoning.
(I also had some stupid support logic that helped a little: "oh, water
is blue so when light goes through it, the light turns blue too!")

Water is actually colourless. The blue in the ocean we see is due to other reasons (was it actually the sky? I vaguely remember someone saying that explanation was wrong). Anyway, I don't remember what's taught in VCE, but Wiki says chlorophyll absorbs blue the most. And we all know Wiki is always right.
shinny i put down red, do you think they will accept both? or only blue?

Given that it's not a typo or anything, I'm pretty sure VCAA will only take blue then. Like stonecold said, they put that question there with a purpose (even if it is a fairly pointless one from my perspective). I seem to recall at least one of the textbooks showing the absorption graph of chlorophyll, and from that it should be fairly obvious that blue is absorbed slightly more. Hence, VCAA can test you on that really, even though it's a detail that no one would ever really care about...bleh, who knows what VCAA was trying to achieve with that question.
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simpak

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Re: 2010 biology unit three exam
« Reply #95 on: June 13, 2010, 05:38:50 pm »
Yes but the absorption graph of chlorophyll is divided into two peaks, one for c. a and one for c. b.
I stick by red because c. a. absorbs red and is the main pigment in photosynthesis, whereas c. b. is only an accessory pigment.
I would also add that just because c. b. absorbs more of a particular wavelength does not mean that the amount of c. b. present in the leaf is greater than that of c. a.
There may be a lot of c. a. in the leaf and a little of c. b., which would mean the plant in the red light would photosynthesize more efficiently.
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shinny

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Re: 2010 biology unit three exam
« Reply #96 on: June 13, 2010, 05:51:33 pm »
Yes but the absorption graph of chlorophyll is divided into two peaks, one for c. a and one for c. b.
I stick by red because c. a. absorbs red and is the main pigment in photosynthesis, whereas c. b. is only an accessory pigment.
I would also add that just because c. b. absorbs more of a particular wavelength does not mean that the amount of c. b. present in the leaf is greater than that of c. a.
There may be a lot of c. a. in the leaf and a little of c. b., which would mean the plant in the red light would photosynthesize more efficiently.

Hmm yeh, my quick Wiki and google image search said that it was blue but having read further, chlorophyll A is primarily involved in photosynthesis and absorbs more red as you said. I really have no idea now. Hurrah for VCAA.

EDIT: Apparently B is also found more so in land plants, not aquatic ones like the question was referring to. Also weirdly enough, Wiki also has this graph which appears quite wrong. Is Wiki wrong for once?  :-\
« Last Edit: June 13, 2010, 05:53:48 pm by shinny »
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lexitu

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Re: 2010 biology unit three exam
« Reply #97 on: June 13, 2010, 06:43:01 pm »
VCAA has head problems. No doubt photosynthesis is in the study design but we are not expected to know about different plant species. In fact it pisses me off that some questions seem to encourage us to acknowledge variations in nature (laundry powder question) but then they give us this bullshit question where we have no information about the plant aside from knowing it is a 'water plant'. Are they trying to say that every single water plant has the same concentration of different pigments? Grr.

stonecold

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Re: 2010 biology unit three exam
« Reply #98 on: June 13, 2010, 06:56:47 pm »
VCAA has head problems. No doubt photosynthesis is in the study design but we are not expected to know about different plant species. In fact it pisses me off that some questions seem to encourage us to acknowledge variations in nature (laundry powder question) but then they give us this bullshit question where we have no information about the plant aside from knowing it is a 'water plant'. Are they trying to say that every single water plant has the same concentration of different pigments? Grr.

Whoever wrote these two questions seriously deserves to lose their job.  And I am supremely confident that they will award both answers now, as the question didn't mention anything about chlorophyll A and B levels.

And all answers should be accepted for laundry powder, as there are several different ways in which you can interpret the question.
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stonecold

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Re: 2010 biology unit three exam
« Reply #99 on: June 13, 2010, 07:16:42 pm »
And for the laundry powder question, this article semi outlines the criteria for "Extremozymes"

Many micro-organisms live under extreme conditions of heat
(100–120o C, deep sea vent) cold (0–4o , sea ice), salinity (>3 M
NaCl, soda lake), acidity (below pH 1, sulphur springs) and
alkalinity (above pH 10, soda lake) from which extremozymes
have been isolated.


http://www.ias.ac.in/resonance/Mar1998/pdf/Mar1998p32-40.pdf

From the alternatives, C would seem to fit best.
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shinny

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Re: 2010 biology unit three exam
« Reply #100 on: June 13, 2010, 07:18:33 pm »
And for the laundry powder question, this article semi outlines the crieteria for "Extremozymes"

Many micro-organisms live under extreme conditions of heat
(100–120o C, deep sea vent) cold (0–4o , sea ice), salinity (>3 M
NaCl, soda lake), acidity (below pH 1, sulphur springs) and
alkalinity (above pH 10, soda lake) from which extremozymes
have been isolated.


http://www.ias.ac.in/resonance/Mar1998/pdf/Mar1998p32-40.pdf

From the alternatives, C would seem to fit best.

Why's this relevant? The options provided were species already isolated.
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stonecold

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Re: 2010 biology unit three exam
« Reply #101 on: June 13, 2010, 07:20:25 pm »
Well the question says that they were extremozymes.  The other 3 alternatives hardly seem "extreme" at all.

Edit: The more I think about it, this is what the question was testing.  It had nothing to do with water temperature/washing machines.  It was testing your understanding of extreme conditions. 

This to me makes sense, as there was no mention of washing machine water temperature, and it would be silly and unfair to expect students to know this.
« Last Edit: June 13, 2010, 07:25:43 pm by stonecold »
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shinny

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Re: 2010 biology unit three exam
« Reply #102 on: June 13, 2010, 07:23:58 pm »
Well the question says that they were extremozymes.  The other 3 alternatives hardly seem "extreme" at all.

The question already states that all the species given are bacteria or archaea which make extremozymes though. The point of the question isn't to figure out which is an extremozyme, but which one is the most suitable for the job at hand.

EDIT: As for the answer, I'm still fairly certain it's C considering that it will not denature in any circumstances a washing machine is likely to encounter.
« Last Edit: June 13, 2010, 07:26:21 pm by shinny »
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stonecold

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Re: 2010 biology unit three exam
« Reply #104 on: June 13, 2010, 07:33:26 pm »
Well the question says that they were extremozymes.  The other 3 alternatives hardly seem "extreme" at all.

The question already states that all the species given are bacteria or archaea which make extremozymes though. The point of the question isn't to figure out which is an extremozyme, but which one is the most suitable for the job at hand.

EDIT: As for the answer, I'm still fairly certain it's C considering that it will not denature in any circumstances a washing machine is likely to encounter.

That's all I wanted to hear haha.  Really dumb question though.  I hope for everyone's sake it gets scrapped.  It would be ridiculously unfair to lose a mark on it.  :(
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