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March 28, 2024, 11:12:26 pm

Author Topic: VCE Biology Question Thread  (Read 3570471 times)  Share 

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Coolgalbornin03Lo

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Re: VCE Biology Question Thread
« Reply #13155 on: October 30, 2020, 10:01:23 pm »
0
Is an opening a cluster of genes under control of the same promoter region

Or

A cluster of genes under the control of a single promoter and operator region?
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Varahi

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Re: VCE Biology Question Thread
« Reply #13156 on: October 30, 2020, 10:15:04 pm »
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:)

-Lilac-

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Re: VCE Biology Question Thread
« Reply #13157 on: October 30, 2020, 11:31:05 pm »
+8
Is an opening a cluster of genes under control of the same promoter region

Or

A cluster of genes under the control of a single promoter and operator region?

Hi, do you mean an operon instead of an opening?

If so, an operon is a group of genes under the same promoter such as they are transcribed as one polycistronic mRNA.  Depending on who you ask, the operator is either kinda part of the promotor or between the promoter and coding sequence (at least in the lac operon). Therefore, I personally wouldn't worry about specifying the operator in a definition just that the repressor protein binds the operon.

But someone else may want to confirm that because I am not too up to date with the specifics of VCE bio.
« Last Edit: October 30, 2020, 11:33:21 pm by -Lilac- »
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #13158 on: October 31, 2020, 11:43:20 am »
+7
A section of a DNA strand has the base sequence AGCGCATAGCAA.
During DNA replication to form the complementary DNA strand, a mutation involving a single base
substitution occurred in the last triplet of this section.
This mutation was then passed on to the mRNA when transcription of the complementary strand occurred.
The base sequence of the mRNA containing the mutation could be
A.    AGCGCAUAGCAA
B.    AGCGCAUAGUAA
C.    UCGCGUAUCGUU
D.    UCGCGUAUCAUU

Why is the answer to this D and not B? I thought the mRNA sequence would be complementary to the complementary strand, so it would have the same base sequence as first given in the question as this would be the coding strand.
Okay so I've had a look through all the past exams. I found about 5 similar questions. Every question bar one specified that they were referring to the template strand or asked for the mRNA strand that would be "complementary" to the given DNA strand. There was one question that asked for the "corresponding" DNA sequence to a given mRNA sequence. With the supplied answer they must have been referring to the complementary sequence. Ie. For every single vcaa question other than the one you've found, when they've asked a question like this they've meant for it to be assumed to be the template strand NOT the coding strand, and for the vast majority they've specified which it is. VCAA does make mistakes sometimes and I think this is one of them. If you got this exact question in your exam I'd recommend picking B.
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SmartWorker

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Re: VCE Biology Question Thread
« Reply #13159 on: October 31, 2020, 01:39:05 pm »
+1
Is it true that "all members of the same species have the same genome", its from the examiner's report for 2013 exam, qu 12a

The study design defines: genome "as the sum total of an organism’s DNA measured in the number of base pairs contained in a
haploid set of chromosomes"

Isn't there a contradiction? because the number of bp can vary between members of the same species. Example: STRs vary in number of repeats between persons to person?
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Re: VCE Biology Question Thread
« Reply #13160 on: October 31, 2020, 04:11:15 pm »
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Re: VCE Biology Question Thread
« Reply #13161 on: November 01, 2020, 01:17:50 pm »
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Experimental design question: why is it necessary to leave the organisms to acclimatise in a respirometer for a few minutes before measuring O2 intake in aerobic respiration? (In the experiment O2 is used up causing the liquid to move, for some background)
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Coolgalbornin03Lo

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Re: VCE Biology Question Thread
« Reply #13162 on: November 01, 2020, 05:56:13 pm »
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In VCAA 2017 Exam question MC 24 why is the answer C instead of A. When self reactive B and T cells are present doesn’t that mean our self antigens are kind of like allergens? Because they are a usually innocuous substance which is eliciting an immune response?

EDIT: also for Q25 isn’t option D too much of a generalisation to get from the results? It’s such a broad statement

Is Q36 still relevant to the study design or does it (answer B) border on cultural evolution- which was taken out?
« Last Edit: November 01, 2020, 05:59:17 pm by Coolgalbornin03Lo »
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Re: VCE Biology Question Thread
« Reply #13163 on: November 01, 2020, 06:23:35 pm »
+4
In VCAA 2017 Exam question MC 24 why is the answer C instead of A. When self reactive B and T cells are present doesn’t that mean our self antigens are kind of like allergens? Because they are a usually innocuous substance which is eliciting an immune response?

EDIT: also for Q25 isn’t option D too much of a generalisation to get from the results? It’s such a broad statement

Is Q36 still relevant to the study design or does it (answer B) border on cultural evolution- which was taken out?
This was my exam (ahhh the memories, lets break this down)
MC Q24: it seems like your mixing up the mechanisms of allergies and autoimmune disease. Allergies respond to an exogenous antigen, something that is outside the body, whereas in MS self-cells target and damages the myelin which is mediated by T helper cells. That's why C is correct. I encourage you to review this topic on autoimmune disease and be confident to distinguish between the diseases covered in the study design.
MC Q25: yes its a generalisation, but a logical one given the limited information you have, if MS females are less likely to get a H. pylori infection this suggets H. pylori exposure protect against MS, as females who get a H. pylori infection do not get MS. Again a generalisation, but this question is testing your ability to come to logical conclusions. A-C were either unlogical or factually incorrect from the information provided, I encourage you to use the process of elimination to answer these type questions, it is evident that A-C were not consistent with the results provided.
MC Q36: is likely not examinable as it tests cultural evolution
Hope this helps!
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Coolgalbornin03Lo

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Re: VCE Biology Question Thread
« Reply #13164 on: November 01, 2020, 08:05:42 pm »
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I was wondering for natural selection should you take the “positive” or “negative“ view?

 I define it as the process in which individuals which are suited to the environment are more likely to survive and reproduce passing on their favourable alleles to the next gen.

But my friend who did bio last year did the “negative”:

Individuals unsuitable to the environment are eliminated by environment (or something along these lines)

Are they both the same or is the second one more correct?


Isn’t gene flow also known as migration? In the 2017 biology exam Q5a they said it’s incorrect to say so but my answer was:

Spoiler
Gene flow is the transfer of alleles between two populations due to migration which allows interbreeding
Because of that 1 tiny word I gave my self 2 marks not 3 (0 on this part- the other 2 come from the rest of the questions asking whether gene flow occurs there and why)

I learnt it’s migration in class and the atarnotes book says so as wel!!

Mod Edit: Merged double posts
« Last Edit: November 02, 2020, 05:22:40 pm by Erutepa »
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WhatisaMeMe

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Re: VCE Biology Question Thread
« Reply #13165 on: November 01, 2020, 10:59:06 pm »
0
I was wondering for natural selection should you take the “positive” or “negative“ view?

 I define it as the process in which individuals which are suited to the environment are more likely to survive and reproduce passing on their favourable alleles to the next gen.

But my friend who did bio last year did the “negative”:

Individuals unsuitable to the environment are eliminated by environment (or something along these lines)

Are they both the same or is the second one more correct?

there is no difference


Isn’t gene flow also known as migration? In the 2017 biology exam Q5a they said it’s incorrect to say so but my answer was:

Spoiler
Gene flow is the transfer of alleles between two populations due to migration which allows interbreeding
Because of that 1 tiny word I gave my self 2 marks not 3 (0 on this part- the other 2 come from the rest of the questions asking whether gene flow occurs there and why)

I learnt it’s migration in class and the atarnotes book says so as wel!!
gene flow is the result of migration, but not exactly migration. individuals migrate between populations which means that alleles between are moved between populations as they interbreed

Mod Edit: Merged double post
« Last Edit: November 02, 2020, 05:24:52 pm by Erutepa »
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M-D

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Re: VCE Biology Question Thread
« Reply #13166 on: November 04, 2020, 06:46:51 am »
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Hi everyone,

Question 11c of the VCAA 2017 Exam is as follows: Explain why Matthew recorded the data for four minutes and not just one minute.

The VCAA solutions state: To establish a baseline for the experiment.

Could someone please explain this in further detail. What is a baseline in this context. Is it a control or similar? Why was the data recorded for 4 minutes, not ? Thanks

homeworkisapotato

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Re: VCE Biology Question Thread
« Reply #13167 on: November 04, 2020, 07:08:42 am »
+5
A baseline is used to act as a standard for comparison in the experiment. They measure it for four minutes to ensure that no confounding variables are affecting it and to ensure that all variables stay constant. It's more reliable to measure for four minutes rather than one as you can ensure that the variables are constant and will be constant. After they fully conduct their experiment, they can compare the effects of the independent variable to the initial starting point (the baseline). So in the experiment, the baseline serves to make sure the oxygen concentration stays the same, and so that after the experiment if the oxygen increases/decreases they can measure the change.
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M-D

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Re: VCE Biology Question Thread
« Reply #13168 on: November 04, 2020, 12:11:55 pm »
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Thanks homeworkisapotato.

How is a baseline different from a control then?

And will the timing (in this instance 4 min) differ from one experiment to another based upon what is being tested? There isn't a stock standard timing that is applicable in all experiments?

Coolgalbornin03Lo

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Re: VCE Biology Question Thread
« Reply #13169 on: November 04, 2020, 03:12:46 pm »
+4
Thanks homeworkisapotato.

How is a baseline different from a control then?

And will the timing (in this instance 4 min) differ from one experiment to another based upon what is being tested? There isn't a stock standard timing that is applicable in all experiments?

A control groups acts as a baseline to compare the results of the experimental group to and determine the true effect of the IV on the DV.

But in this case a baseline is like a “reference point” they test it for 4 minutes to see what it “usually” is. And then that becomes the “reference” point. I hope this makes sense!
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