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October 22, 2020, 12:32:41 am

Author Topic: VCE Biology Question Thread  (Read 1844438 times)  Share 

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Coolgalbornin03Lo

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Re: VCE Biology Question Thread
« Reply #13005 on: September 24, 2020, 03:42:02 pm »
+2
Thank you! Why do primers always bind to the 3' end?

I thought they bind either side of the gene of interest? As in one on the 3 prime end of one strand and on the 3 prime end of another strand? Because before anneal stage the DNA has disassociates  into single strands?

Maybe it’s because the template strand is 3’ to 5’?

EDIT: since you said primers I assumed we were talking about PCR, but I looked back at the previous comments and You were talking About transcription before. If this is still transcription,, there’s no primers and RNA polymerase reads the template strand 3’ to 5’ because the template strand is 3’ to 5’, and as a result pre-mRNA is complementary 5’-3’.


« Last Edit: September 24, 2020, 03:47:11 pm by Coolgalbornin03Lo »
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homeworkisapotato

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Re: VCE Biology Question Thread
« Reply #13006 on: September 24, 2020, 03:52:27 pm »
0
I thought they bind either side of the gene of interest? As in one on the 3 prime end of one strand and on the 3 prime end of another strand? Because before anneal stage the DNA has disassociates  into single strands?

Maybe it’s because the template strand is 3’ to 5’?

EDIT: since you said primers I assumed we were talking about PCR, but I looked back at the previous comments and You were talking About transcription before. If this is still transcription,, there’s no primers and RNA polymerase reads the template strand 3’ to 5’ because the template strand is 3’ to 5’, and as a result pre-mRNA is complementary 5’-3’.

Thank you! I was talking about PCR sorry for not clarifying
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-Lilac-

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Re: VCE Biology Question Thread
« Reply #13007 on: September 24, 2020, 04:06:30 pm »
+3
I thought they bind either side of the gene of interest? As in one on the 3 prime end of one strand and on the 3 prime end of another strand? Because before anneal stage the DNA has disassociates  into single strands?

Maybe it’s because the template strand is 3’ to 5’?

EDIT: since you said primers I assumed we were talking about PCR, but I looked back at the previous comments and You were talking About transcription before. If this is still transcription,, there’s no primers and RNA polymerase reads the template strand 3’ to 5’ because the template strand is 3’ to 5’, and as a result pre-mRNA is complementary 5’-3’.

Yep, PCR uses forward and reverse primers. The primers are on the 3' ends of the strands as DNA polymerase synthesizes a new strand in the 5'–3' direction.

Transcription does not require the use of primers as RNA polymerase can initiate RNA synthesis without them. In contrast, DNA polymerase cannot initiate DNA synthesis without a primer as it requires a free 3′-OH group to extend from.

With hardy Weinberg how do you remember that p is dominant and q is recessive


I used to remember this by thinking that since q is a more rare letter than p it means recessive which is also rarer.
« Last Edit: September 24, 2020, 04:11:10 pm by -Lilac- »
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dedformed

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Re: VCE Biology Question Thread
« Reply #13008 on: September 24, 2020, 04:29:58 pm »
0
does anyone here know a good way of remembering/ explaining 3' and 5' strands like i relearned it a hundred times but i keep mixing them up. which way is downstream? do i even need to know?
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-Lilac-

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Re: VCE Biology Question Thread
« Reply #13009 on: September 24, 2020, 09:13:52 pm »
+5
does anyone here know a good way of remembering/ explaining 3' and 5' strands like i relearned it a hundred times but i keep mixing them up. which way is downstream? do i even need to know?


Is there anything specific you are having problems with? Transcription, translation or replication etc???

As you know, the DNA strands run anti-parallel to each other.

DNA replication always results in daughter strand synthesis in the 5' - 3' direction. The lagging strand is also synthesized discontinuously as it is formed away from the replication fork.

5' AAATTTCCC 3' (leading strand)
      <---------- 5'
5' ----> 5' ---->
3' TTTAAAGGG 5' (lagging strand)

Transcription by RNA pol will also occur in the 5' - 3' direction.

5' AAATTTCCC 3' (coding strand)
5' -------------> (mRNA)
3' TTTAAAGGG 5' (template strand)

mRNA is then read by the ribosome from the 5' to the 3'.

Regarding upstream and downstream, this usually refers to where a point in the sequence is relative to a gene on the coding strand. I don't think you need to know this for VCE though.

5' AAATTTCCC 3' (coding strand)
3' TTTAAAGGG 5' (template strand)

For example, let's say our gene sequence is ATTTC (bold). Then we can say that the AA towards the 5' end is upstream of the gene and the CC towards the 3' end is downstream of the gene. You will often hear promotors referred to as upstream, as they are located before the coding sequences towards the 5' end of the coding strand.
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Coolgalbornin03Lo

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Re: VCE Biology Question Thread
« Reply #13010 on: September 24, 2020, 10:23:05 pm »
+3
does anyone here know a good way of remembering/ explaining 3' and 5' strands like i relearned it a hundred times but i keep mixing them up. which way is downstream? do i even need to know?

Just remember that mRNA is 5’ to 3’. It’s the key to everything. By remembering only that:

We know the template strand is 3’ to 5’ as RNA polymerase reads it and mRNA is complementary.

Coding is 5’ to 3’ bc you know opposite of template.

And the anticodons = 3’ to 5’ like the template strand :)
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Bri MT

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Re: VCE Biology Question Thread
« Reply #13011 on: September 24, 2020, 10:52:29 pm »
+2
With hardy Weinberg how do you remember that p is dominant and q is recessive

it's standard in probability that q = 1-p. It does not matter for the HW maths at all whether you have p or q as recessive & you also don't need to remember the HW equations for the current study design :)

homeworkisapotato

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Re: VCE Biology Question Thread
« Reply #13012 on: September 25, 2020, 09:31:35 am »
0
If promoters are at the 5' end, then why aren't mRNA strands synthesised 3' to 5'? Wouldn't RNA polymerase have to bind to the promoter first and continue downstream to the 3' end?
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Owlbird83

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Re: VCE Biology Question Thread
« Reply #13013 on: September 25, 2020, 09:56:11 am »
+5
If promoters are at the 5' end, then why aren't mRNA strands synthesised 3' to 5'? Wouldn't RNA polymerase have to bind to the promoter first and continue downstream to the 3' end?

The RNA polymerase binds to the promotor region when the two strands are together, and then it separates the two strands of DNA, and then it goes along the 'template strand' which is the 3' to 5' strand to synthesise the 5' to 3' mRNA.
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p0kem0n21

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Re: VCE Biology Question Thread
« Reply #13014 on: September 27, 2020, 10:16:30 am »
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Hey guys! I'm planning on doing bio 3/4 next year for year 11 without doing the 1/2. While I am not too concerned about learning the content, I'm more worried about learning HOW to answer short/long-answer questions in a concise, but 'full' manner. What can I do to improve this skill?
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homeworkisapotato

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Re: VCE Biology Question Thread
« Reply #13015 on: September 27, 2020, 10:20:49 am »
+4
Hey guys! I'm planning on doing bio 3/4 next year for year 11 without doing the 1/2. While I am not too concerned about learning the content, I'm more worried about learning HOW to answer short/long-answer questions in a concise, but 'full' manner. What can I do to improve this skill?
Hi! Practice is key and doing practice questions consistently throughout the year and marking them will allow you to find your mistakes and fix them. The best thing to do is before answering the questions, plan out your response and think of any key terms to put in your answer. For example, with enzymes I usually mention 'specific active site' or 'enzyme-subtrate complex.'You won't get this ability straight away and it will take time, so the best thing to do is practice this in the summer holidays and eventually you will see some spicy progress. All the best!
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miyukiaura

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Re: VCE Biology Question Thread
« Reply #13016 on: September 27, 2020, 03:08:24 pm »
0
What is some evidence that supports the multiregional theory of human evolution? I know physical differences between current sapiens populations and the lack of genetic diversity in current humans are evidence, but how does this support the theory?
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Owlbird83

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Re: VCE Biology Question Thread
« Reply #13017 on: September 27, 2020, 04:44:13 pm »
+6
What is some evidence that supports the multiregional theory of human evolution? I know physical differences between current sapiens populations and the lack of genetic diversity in current humans are evidence, but how does this support the theory?
The physical differences supports the multiregional theory because it hypothesises that homo sapiens evolved mostly separately for a much longer time than the out of Africa hypothesis, so more time for differences to occur. (I might be wrong, but are you sure lack of genetic diversity supports the multiregional theory, because I thought higher genetic diversity would support it because multiregional suggests humans spread out a lot earlier than the out-of-Africa?). I think the fossil record provided evidence for multiregional, whereas now that newer technology can be used, we can use genetic evidence which supports the out-of-Africa hypothesis. Anyone please correct me if I'm wrong
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whys

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Re: VCE Biology Question Thread
« Reply #13018 on: September 27, 2020, 05:58:22 pm »
+6
The physical differences supports the multiregional theory because it hypothesises that homo sapiens evolved mostly separately for a much longer time than the out of Africa hypothesis, so more time for differences to occur. (I might be wrong, but are you sure lack of genetic diversity supports the multiregional theory, because I thought higher genetic diversity would support it because multiregional suggests humans spread out a lot earlier than the out-of-Africa?). I think the fossil record provided evidence for multiregional, whereas now that newer technology can be used, we can use genetic evidence which supports the out-of-Africa hypothesis. Anyone please correct me if I'm wrong
I think low genetic diversity supports the theory because it supports that there was consistent gene flow between different populations of H. Sapiens, which helped them all evolve into H. Sapiens in the end.

homeworkisapotato

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Re: VCE Biology Question Thread
« Reply #13019 on: September 27, 2020, 07:00:45 pm »
+1
Hey! For plant barriers, is it enough to know physical and chemical barriers?
For physical I remember cellulose, bark, and waxy cuticles of leaves and for chemical I know oxalic acid (substance excreted and is toxic when ingested), phenol (secreted by wounded plants which repel/kill microorganisms), and saponin which disrupts the membrane of fungi.
Are there any for each you would recommend knowing?
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