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March 29, 2024, 05:08:41 am

Author Topic: VCE Biology Question Thread  (Read 3570799 times)  Share 

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C14M8S

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Re: VCE Biology Question Thread
« Reply #10845 on: October 19, 2018, 07:27:46 am »
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Ok I've still got more questions -
1) Does the repressor bind the promoter region or the operator region? I've heard both answers from practice exams so I'm unsure.
2) What is the 'baseline' of an experiment in layman's terms? (2017 exam 11c)
3) What is the difference between experimental accuracy, reliability, and precision?
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PopcornTime

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Re: VCE Biology Question Thread
« Reply #10846 on: October 19, 2018, 08:39:28 am »
+9
Ok I've still got more questions -
1) Does the repressor bind the promoter region or the operator region? I've heard both answers from practice exams so I'm unsure.
2) What is the 'baseline' of an experiment in layman's terms? (2017 exam 11c)
3) What is the difference between experimental accuracy, reliability, and precision?

1) Operator region. To learn this you have to think about this logically. Below would be the Lac Operon:

Regulatory gene (not apart of it)                    Promoter                 Operator                 Structural genes (Lac Z, Lac Y, Lac A)

- the repressor protein would have to bind to the operator region
- if the repressor protein did bind to the promoter region, how would it block RNA polymerase (if RNA polymerase was going to bind to operator region)?

2) I think baseline refers to the starting measurement for data. For example, in the first table of page 36 of q11 (2017 exam), you can see slight changes in % concentration and temperature from 0 minutes until 2 minutes. From 2 minutes to 4 minutes, it is the same -- and that is pretty much the baseline.

3) Accuracy refers to the difference between the experimental and true measurement obtained.

Reliability refers to the ability to obtain the same results if the experiment was repeated.

Precision refers to the agreement between values (how close values are) if experiment is repeated.

If someone could check the above that would be good

PopcornTime

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Re: VCE Biology Question Thread
« Reply #10847 on: October 19, 2018, 08:48:07 am »
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Few questions:
1.) Is the diagram attached correct (from 2017 vcaa exam report) question 9 b ii). How can there be another tcl next to ORI? I thought the gene would annealed in between the 2 lines (one line has BamH1 restriction site), and only one tcl would result (next to HindIII).

2.) I'm not very good at the ethics questions when it comes to genetic screening, gene therapy, GMO's, transgenic, etc. Can someone recommend a few for each?

3.) Why is the Answer B for 2017 vcaa bio exam question 14 multi choice. I know it wasn't A and D, but why couldn't answer be C? Couldn't the light have saturated chlorophyll molecules?

4.) Why is the answer D for 2017 vcaa bio exam question 19 multi choice. Couldn't answer be B? Why would D be more correct?

5.) Question 4. a ii) 2017 vcaa bio exam, would I get the mark for the following:
- by washing hands using antibacterial soaps
- by regularly cleaning medical equipment using disinfectants

Thanks!

PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #10848 on: October 19, 2018, 09:08:38 am »
+4
- if the repressor protein did bind to the promoter region, how would it block RNA polymerase (if RNA polymerase was going to bind to operator region)?
RNA polymerase actually binds to the promotor region not the operator region, so having a Repressor attached to the operator stops the polymerase from travelling down the gene and transcribing it. Other than that, everything you’ve said is correct :)


1) It’s not another tcl, the plasmid gets cut at Bamh1, which is in the middle of tcl. The human gene is inserted there, leaving half of tcl on either side.

2) There hasn’t really been that many past exam questions on ethics. I’d recommend just remembering a few ethical issues and then picking whichever is relevant for the scenario you’re given.

3) It’s not saying the chlorophyll is saturated, it’s saying the chlorophyll is damaged. If it was damaged the net output would have gone down, this is not the case - as you can see in the diagram it has remained constant, therefore it can’t be C.

4) Decreased apoptosis in surrounding normal cells wouldn’t cause rapid division of cancer cells - the only option that would cause that is D.

5) If you specified antibacterial then yes.
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PopcornTime

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Re: VCE Biology Question Thread
« Reply #10849 on: October 19, 2018, 12:17:54 pm »
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2017 vcaa bio exam, question 40 multi choice. Why is answer B? How would you justify why other's are wrong?

2018 vcaa bio northern hemisphere exam, question 23. Why is answer A?

2018 vcaa bio northern hemisphere exam, question 29. Why is answer not C?

Thanks!



PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #10850 on: October 19, 2018, 04:05:02 pm »
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2017 vcaa bio exam, question 40 multi choice. Why is answer B? How would you justify why other's are wrong?

2018 vcaa bio northern hemisphere exam, question 23. Why is answer A?

2018 vcaa bio northern hemisphere exam, question 29. Why is answer not C?

Thanks!

40.
Quote
Plant viruses are a major problem for farmers growing crops. A particular plant virus can infect many different plant species. Scientists are trialling a spray treatment on tobacco crops. The treatment does not alter the DNA of the tobacco plants. During this treatment, tobacco plants are sprayed with clay nanoparticles containing double-stranded RNA (dsRNA). The dsRNA released from each of the clay nanoparticles enters the plant cells. Inside each cell the dsRNA silences a gene from the virus by causing viral RNA to break down.
In this technique the
A. dsRNA would have a nucleotide sequence complementary to a section of DNA nucleotides in the tobacco plants. It is double stranded RNA which means it is already bound to complementary bases. Being complmentary to DNA nucleotides is irrelevant.
B. dsRNA would silence a gene from the virus by initiating changes that prevent translation of the viral gene. Given that the question states that the dsRNA acts on viral RNA, it makes sense that it would prevent translation.
C. spray treatment would be effective only on tobacco plants and not on other plant species. The question specifies that the virus affects many species, it is just happens to be tobacco plants that they’re trialling it on
D. sprayed tobacco plants would be regarded as transgenic organisms. The question specifies that it does not alter the plants DNA so the plants won’t be transgenic

23. A
The branching off lines represent a difference in evolution. The order they branch off in represents the order those characteristics evolved in. Archaea and bacteria don’t have mitochondria or chloroplasts so they branch off first (Everything on the 2 left branches has neither mitochondria or chloroplasts, everything on the right branch has mitochondria – indicated by the right branch being named ‘mitochondria’). Then fungi and animals split from plants (everything on the 2 left branches has mitochondria but not chloroplasts, the right branch is labelled ‘chloroplasts’ so everything on that branch (ie. plants) have chloroplasts).

29. The answer is C.
« Last Edit: October 19, 2018, 04:34:50 pm by PhoenixxFire »
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$noopDodd

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Re: VCE Biology Question Thread
« Reply #10851 on: October 19, 2018, 10:19:22 pm »
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How do high temperatures affect the integrity of the cell membrane on a molecular level? (beetroot prac)
from what I've gathered: increasing temp = higher kinetic energy of molecules = more fluidity -> gaps in the plasma membrane --> allowing pigment to escape beetroot cells and enter the solution

Also whats the purpose of a control?, for say a 2 mark question (according to VCAA exam reports)
I've heard varying responses from company notes, my teacher and online resources for this, not sure what to follow

Thanks
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #10852 on: October 20, 2018, 09:38:30 am »
+2
How do high temperatures affect the integrity of the cell membrane on a molecular level? (beetroot prac)
from what I've gathered: increasing temp = higher kinetic energy of molecules = more fluidity -> gaps in the plasma membrane --> allowing pigment to escape beetroot cells and enter the solution
Yep. All of this is correct.

Also whats the purpose of a control?, for say a 2 mark question (according to VCAA exam reports)
I've heard varying responses from company notes, my teacher and online resources for this, not sure what to follow

Thanks
The control is to give you something to compare your results to/give you a baseline for the experiment. Like if you were testing the effect of increased concentrations of carbon dioxide on plant growth, but all you had was one plant in a sealed container that contained higher than usual CO2, what would you compare that too? Just from that you can’t tell what affect the co2 has on it. Your control would be another plant in a sealed container with normal levels of co2, that way you can actually see what difference the increased co2 made.
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C14M8S

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Re: VCE Biology Question Thread
« Reply #10853 on: October 20, 2018, 10:19:29 am »
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1) Where are mast cells located? I said connective tissue (VCAA 2002 Unit 3 Q7a) but apparently the correct answer is blood vessels. What should I go with?
2) What are the differences between systemic and random error? I understand that random error is affected by alternate variables and the experimenter's incompetence, and systemic error is the measuring utensil being inaccurate, but do I need to know any more?
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zsteve

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Re: VCE Biology Question Thread
« Reply #10854 on: October 20, 2018, 11:45:32 am »
+2
1) Where are mast cells located? I said connective tissue (VCAA 2002 Unit 3 Q7a) but apparently the correct answer is blood vessels. What should I go with?
2) What are the differences between systemic and random error? I understand that random error is affected by alternate variables and the experimenter's incompetence, and systemic error is the measuring utensil being inaccurate, but do I need to know any more?

Q2) Not quite

Systematic error is built into the experiment, e.g. if a thermometer is consistently off by 2 degrees. Systematic errors always occur in the same direction.
Random errors are due to natural inaccuracies in measurement can't be eliminated from the design of experiment and can be removed by replication and averaging.
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #10855 on: October 20, 2018, 12:12:05 pm »
+2
1) Where are mast cells located? I said connective tissue (VCAA 2002 Unit 3 Q7a) but apparently the correct answer is blood vessels. What should I go with?
Definitely connective tissue. The answer for that question says around blood vessels - ie. in connective tissue. Saying they're in blood vessels is effectively the same as saying they're in the blood stream - which VCAA has said is incorrect in that question.
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Robot10

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Re: VCE Biology Question Thread
« Reply #10856 on: October 20, 2018, 02:46:19 pm »
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I’ve got a few Qns. See attached.

1. With Qn 1, is there an error in the diagram/question with Region A being the intracellular environment and Region B being the extracellular fluid.

2. With Qn 14, why is the answer B as opposed to D as aren’t cancer cells stimulated by the extrinsic pathway of apoptosis.

3. For Qn 23, can someone explain why is the answer C and not D
4. Also for Qn 38 could the answer also be D The answer is B

Thanks

PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #10857 on: October 20, 2018, 03:07:36 pm »
+1
I’ve got a few Qns. See attached.

1. With Qn 1, is there an error in the diagram/question with Region A being the intracellular environment and Region B being the extracellular fluid.

2. With Qn 14, why is the answer B as opposed to D as aren’t cancer cells stimulated by the extrinsic pathway of apoptosis.

3. For Qn 23, can someone explain why is the answer C and not D
4. Also for Qn 38 could the answer also be D The answer is B

Thanks
1. TBH I don't even know what's up with that question. It asks about a hydrophobic molecule so presumably the answer is B? But even then that's a really bad diagram of it. If they're saying that the answer is anything other than B then yes they screwed up. Otherwise it's just a weird question. (I would have expected to see a receptor that's not attached to the membrane for a question like that).

2. This might be because a trait of cancer cells is that they have mutations that allow them to avoid apoptosis. Weird question though.

3. Your answer needs to be based on the information provided ('according to this system of classification') - there's nothing in the question about oppose-able thumbs

4. This is a bit of a weirdly worded question, similar to the above. It's just asking you to interpret the graph, not explain the results of the graph. Ie. the trend shown is that it's decreasing. That trend is shown because we are recording less product each time (which is probably due to decreasing substrate - but that's not what the question is asking).
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C14M8S

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Re: VCE Biology Question Thread
« Reply #10858 on: October 20, 2018, 03:16:06 pm »
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1) What is the purpose of a vacuole in a plant? Do I need to know anything aside from that it maintains the correct osmotic pressure?
2) What is the difference between clonal selection and expansion? I'm assuming selection is what usually removes autoimmune lymphocytes before they are released and expansion is the initial phase of mass proliferation?
3) What is the difference between an organelle being made of membrane vs "membrane bound"?
4) Why are coenzymes described as electron carriers?
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Robot10

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Re: VCE Biology Question Thread
« Reply #10859 on: October 20, 2018, 03:35:23 pm »
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1. TBH I don't even know what's up with that question. It asks about a hydrophobic molecule so presumably the answer is B? But even then that's a really bad diagram of it. If they're saying that the answer is anything other than B then yes they screwed up. Otherwise it's just a weird question. (I would have expected to see a receptor that's not attached to the membrane for a question like that).

2. This might be because a trait of cancer cells is that they have mutations that allow them to avoid apoptosis. Weird question though.

3. Your answer needs to be based on the information provided ('according to this system of classification') - there's nothing in the question about oppose-able thumbs

4. This is a bit of a weirdly worded question, similar to the above. It's just asking you to interpret the graph, not explain the results of the graph. Ie. the trend shown is that it's decreasing. That trend is shown because we are recording less product each time (which is probably due to decreasing substrate - but that's not what the question is asking).


Thanks  For question 1, I was just wondering whether the glycolipids and glycoproteins should face the extracellular environment not the intracellular environment.