VCE Biology Question Thread

[blacksanta62]

Yo, I would love some help with these questions:
1) What is a great definition for a gene? Is this okay - "A gene is a segment of DNA which codes for a specific trait or protein"
2) If asked to explain why DNA replication is considered "easy and error free" would this be a suitable answer: "Because of DNA polymerases ability to check and remove incorrect nucleotides DNA replication is generally error free. Furthermore, a cell has the ability to check the replicated DNA at G2 making any repairs to the DNA strand"
The answer the book gives is because of the relatively easy base-pairing which applies to DNA replication
3) Can anyone explain the experiment with heavy N₂ and regular N₂ please? I don't understand how it helped us understand DNA is semi-conservative.
4) Does semi-conservative just mean that we reuse the DNA strands of the original DNA molecule in the new one?

Sorry for all the questions, I have a SAC on Friday.
Thank you

[studybuddy7777]

Yo, I would love some help with these questions:
1) What is a great definition for a gene? Is this okay - "A gene is a segment of DNA which codes for a specific trait or protein"
2) If asked to explain why DNA replication is considered "easy and error free" would this be a suitable answer: "Because of DNA polymerases ability to check and remove incorrect nucleotides DNA replication is generally error free. Furthermore, a cell has the ability to check the replicated DNA at G2 making any repairs to the DNA strand"
The answer the book gives is because of the relatively easy base-pairing which applies to DNA replication
3) Can anyone explain the experiment with heavy N₂ and regular N₂ please? I don't understand how it helped us understand DNA is semi-conservative.
4) Does semi-conservative just mean that we reuse the DNA strands of the original DNA molecule in the new one?

Sorry for all the questions, I have a SAC on Friday.
Thank you

No worries happy to answer the first 2 as they also apply to the HSC course!
1. A gene is a segment of DNA which codes for a specific trait or protein This is basically the exact definition that I have, so I would say that its fine!!
2 I would think is acceptable for an answer but i see where the textbook is coming from saying "easy base-pairing" because that is one aspect of it. Maybe just try and integrate that into your response?

Sorry I cant help with question 3 and 4 but hope i helped with Q 1 and 2!

[blacksanta62]

Thank you so much. Any help is great help. And yeah, I'll take your advice and try integrate it

[studybuddy7777]

Thank you so much. Any help is great help. And yeah, I'll take your advice and try integrate it

No worries at all!! Quite often i scour through VCE threads to help me with HSC questions so you might see me down here a bit (Plus have a bio exam next week Thursday so good revision!)

[gameboy99]

Hi guys,
I have had a burning question for a long time and decided to post it up to the AN community.
I really have studied hard this year for biology but my teachers have marked very harshly and unfairly at times. If not for the unfair marking I think I would have averaged high A+.I have got 82/100 total sac marks for Unit 3 which is slightly over the average(pretty high sac average at my school) .There is another 100 sac marks for Unit 4.
Taking into consideration I am in a selective entry school, can any past biology student give me approximate marks I have to get for my unit 4 sacs and end of year exam to get a 42+.
My goal this year was to get 45+, do I still have the chance to get this score?

I would appreciate if someone could answer my burning question.
Thanks

[blacksanta62]

No worries at all!! Quite often i scour through VCE threads to help me with HSC questions so you might see me down here a bit (Plus have a bio exam next week Thursday so good revision!)

Good luck with the exam

Hi guys,
I have had a burning question for a long time and decided to post it up to the AN community.
I really have studied hard this year for biology but my teachers have marked very harshly and unfairly at times. If not for the unfair marking I think I would have averaged high A+.I have got 82/100 total sac marks for Unit 3 which is slightly over the average(pretty high sac average at my school) .There is another 100 sac marks for Unit 4.
Taking into consideration I am in a selective entry school, can any past biology student give me approximate marks I have to get for my unit 4 sacs and end of year exam to get a 42+.
My goal this year was to get 45+, do I still have the chance to get this score?

I would appreciate if someone could answer my burning question.
Thanks

lol, I was about to post when this came up
That's a very high SAC average. You're in a strong cohort and you seem very determined. A 45+ is still very possible, but keep your eyes on that exam. That's the be all end all (especially if your in a weak cohort ) and determines your SS. If that bombs, so do your hopes and the 82/100 SAC mark (top cohorts they don't generally care about rankings. I think it's assumed by everyone in the cohort that if everyone does well on the exam, we all win)

[studybuddy7777]

Good luck with the exam :)lol, I was about to post when this came up

Thank you!! And goodluck for you SAC on Friday im sure youll ace it!

[sweetcheeks]

@blacksanta62

The experiment performed using an isotope of nitrogen (N15) was placing e.coli bacteria in cultures where the only nitrogen available (required for DNA base synthesis) was N15. The e.coli was cultured for multiple generations to produce bacteria that have DNA consisting of almost entirely N15. These N15 e.coli were then placed in an environment consisting of only N14 isotopes.

The bacteria were allowed to replicate and DNA was extracted periodically. To replicate, the bacteria would have to use the N14 to synthesise the bases. After controlled replication and extracted, DNA was extracted and placed in a centrifuge. If DNA was conserved (one entirely new strand and one old strand) then it should have separated clearly (N15 would go to the bottom). However, when tested there was no clear separation, indicating that the DNA was a mixture of N15 and N14.

If DNA was conserved, there would have been clear separation, as there would be a 15 strand and 14 strand, rather than a combination.


Semiconservative means that each of the two DNA molecules will contain one parent strand (old) and a fresh strand (new).

[blacksanta62]

Thanks sweetcheeks, another question, does the study design or has your biology teacher ever put this on a SAC? The experiment itself? I don't think I need to 'know it' but could it be tested.

Thank you

[sweetcheeks]

I have just done a gel electrophoresis/ restriction enzyme experiment.

A question in the booklet gives a DNA sequence and we had to find where it cuts. It said that the fragment size could be measured in base-pair lengths. Do we count the sticky ends when determining length? or do we just count the amount of pairs?

[vox nihili]

I have just done a gel electrophoresis/ restriction enzyme experiment.

A question in the booklet gives a DNA sequence and we had to find where it cuts. It said that the fragment size could be measured in base-pair lengths. Do we count the sticky ends when determining length? or do we just count the amount of pairs?

Count the sticky ends too.

[anotherworld2b]

I have a few questions. For our investigation we were testing the rate of human urine production.
Our hypothesis was that the consumption of caffeine increases the rate of human urine production.
Our experimental group was caffeine (ice tea) and control group was cordial.
In our results the graph of the cordial spiked in the amount of urine produced before the graph of peach ice tea.
Why would this happen? Errors could have occurred? I though caffeine would increase the rate of human urine production?
I also wanted to ask for the discussion would be appropriate to explain what should have happened?
Eg ADH is involved in fluid, in the body; it causes the kidneys to reabsorb water. When ADH is not present there is decreased water reabsorption in the kidneys, which, in turn increases the need to urinate?

Could I have a answer as soon as possible? I have to finish writing my report to hand in tomorrow

[blacksanta62]

Yo guys, just some query's I have, any help would be greatly appreciated :
1)  When explaining the process of transcription, if I was to call the promoter region the initiation region, is that incorrect?
2) How do prokaryotic and eukaryotic  genes differ? I actually misread this question at first and thought it wanted me to talk about the mRNA found in both, I'm just a bit confused
3) If asked to give "two functions of genes" would this answer be suitable:
-Genes code for amino acids which can be translated into polypeptide chains
-Genes control some metabolic processes i.e. regulatory genes
Thank you

[vox nihili]

I have a few questions. For our investigation we were testing the rate of human urine production.
Our hypothesis was that the consumption of caffeine increases the rate of human urine production.
Our experimental group was caffeine (ice tea) and control group was cordial.
In our results the graph of the cordial spiked in the amount of urine produced before the graph of peach ice tea.
Why would this happen? Errors could have occurred? I though caffeine would increase the rate of human urine production?
I also wanted to ask for the discussion would be appropriate to explain what should have happened?
Eg ADH is involved in fluid, in the body; it causes the kidneys to reabsorb water. When ADH is not present there is decreased water reabsorption in the kidneys, which, in turn increases the need to urinate?

Could I have a answer as soon as possible? I have to finish writing my report to hand in tomorrow

Not relevant to VCE, you might like to try the HSC thread. We spoke about this last week.

Yo guys, just some query's I have, any help would be greatly appreciated :
1)  When explaining the process of transcription, if I was to call the promoter region the initiation region, is that incorrect?
2) How do prokaryotic and eukaryotic  genes differ? I actually misread this question at first and thought it wanted me to talk about the mRNA found in both, I'm just a bit confused
3) If asked to give "two functions of genes" would this answer be suitable:
-Genes code for amino acids which can be translated into polypeptide chains
-Genes control some metabolic processes i.e. regulatory genes
Thank you

1. It's not the typical word for it, so call it promoter

2. Not something you should be asked in VCE, so I won't go into it. Very little difference though to be perfectly honest; just that eukaryotes have more complex gene regulation systems really

3. The first is fine, the second probably not. Those genes that control regulatory processes do so by producing proteins that control regulatory functions.

[blacksanta62]

3. The first is fine, the second probably not. Those genes that control regulatory processes do so by producing proteins that control regulatory functions.

How do you suggest I word the answer?
Thank you