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September 25, 2020, 06:50:04 pm

Author Topic: VCE Biology Question Thread  (Read 1810218 times)  Share 

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1729

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Re: VCE Biology Question Thread
« Reply #12810 on: August 01, 2020, 07:18:10 am »
+3
In ruminants (a relationship between cows and fungi) what is the advantage for the cow and what is the advantage for the fungus
If Im understanding that question you are asking. The cows would receive the benefit of breaking down the cellulose they eat and the microbes would be receiving food. The fungus would break down the cellulose for the cow, allowing both the cow and the microbe to get the nutrients.
« Last Edit: August 01, 2020, 08:28:07 am by 1729 »

Bri MT

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Re: VCE Biology Question Thread
« Reply #12811 on: August 01, 2020, 09:08:26 am »
+3
In ruminants (a relationship between cows and fungi) what is the advantage for the cow and what is the advantage for the fungus

A ruminant is a particular type of mammal (e.g. cows, sheep) & I have not seen that term used to describe a symbiotic relationship before

1729

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Re: VCE Biology Question Thread
« Reply #12812 on: August 01, 2020, 09:22:30 am »
+1
A ruminant is a particular type of mammal (e.g. cows, sheep) & I have not seen that term used to describe a symbiotic relationship before
I'm pretty sure the term ruminant in the question is used to desrcibe the animal itself, not the relationship. However, I don't know if Chocolatepistachio worded the question exactly how it was given to him. In the original question it asked.
In ruminants (a relationship between cows and fungi) what is the advantage for the cow and what is the advantage for the fungus
The wording did seem a bit like ruminant described the relationship, so if thats how it was worded then the question is wrong. But if it is worded like how Bri MT suggested.
A ruminant is a particular type of mammal (e.g. cows, sheep) & I have not seen that term used to describe a symbiotic relationship before
Then the question is talking about the animal. Either way, a ruminant is a type of animal and not a type of relationship, though I believe all ruminants make use of this relationship.

SmartWorker

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Re: VCE Biology Question Thread
« Reply #12813 on: August 01, 2020, 09:55:53 am »
+1
For this MC why can't it be B as well, answer is D (I get why but why does B not work?)

The number of cancer cells within the tissue is rapidly increasing. This increase in the number of cancer cells can be explained by
A. increased caspase function within each of the cancer cells.
B. decreased rate of apoptosis in the surrounding normal cells.
C. reduction in size of the nuclei of cancer cells compared to those of normal cells.
D. impaired signalling from death receptors located on the membrane of the cancer cells.
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Owlbird83

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Re: VCE Biology Question Thread
« Reply #12814 on: August 01, 2020, 10:03:41 am »
+3
For this MC why can't it be B as well, answer is D (I get why but why does B not work?)

The number of cancer cells within the tissue is rapidly increasing. This increase in the number of cancer cells can be explained by
A. increased caspase function within each of the cancer cells.
B. decreased rate of apoptosis in the surrounding normal cells.
C. reduction in size of the nuclei of cancer cells compared to those of normal cells.
D. impaired signalling from death receptors located on the membrane of the cancer cells.

The question is asking why no. of cancer cells is increasing, B doesn't really have anything to do with the growth of the cancer cells. It describes something happening to normal cells, so a bit unrelated to what the question is asking.
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SmartWorker

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Re: VCE Biology Question Thread
« Reply #12815 on: August 01, 2020, 10:06:30 am »
+1
The question is asking why no. of cancer cells is increasing, B doesn't really have anything to do with the growth of the cancer cells. It describes something happening to normal cells, so a bit unrelated to what the question is asking.
But doesn't a reduction in the rate of apoptosis of healthy cells result in cancer cells?
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Owlbird83

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Re: VCE Biology Question Thread
« Reply #12816 on: August 01, 2020, 10:13:23 am »
+3
But doesn't a reduction in the rate of apoptosis of healthy cells result in cancer cells?

No not unless they have mutated to grow uncontrollably or not function properly. For example, neurons can live for your whole lifetime, and not undergo apoptosis unless necessary.
The word choice of 'surrounding' in the question also sort of implies that those cells aren't effected by the cancerous mutation, and I don't think vcaa is mean enough to try and trick you like that haha
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SmartWorker

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Re: VCE Biology Question Thread
« Reply #12817 on: August 01, 2020, 10:16:59 am »
+2
No not unless they have mutated to grow uncontrollably or not function properly. For example, neurons can live for your whole lifetime, and not undergo apoptosis unless necessary.
The word choice of 'surrounding' in the question also sort of implies that those cells aren't effected by the cancerous mutation, and I don't think vcaa is mean enough to try and trick you like that haha

Yep thanks!
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SmartWorker

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Re: VCE Biology Question Thread
« Reply #12818 on: August 01, 2020, 11:10:07 am »
+1
How can the formation of a gall limit the spread of pathogens in a plant? I searched on google at it says that it is a symptom of disease instead. This the answer to this question:  Describe one example of a physical method of defence in a plant.

Thanks :)
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homeworkisapotato

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Re: VCE Biology Question Thread
« Reply #12819 on: August 01, 2020, 11:40:38 am »
+8
Galls are basically swells in the plants and act as a physical barrier once the pathogens enter through the stomata (openings of leaves to let in CO2 for photosynthesis). They block the pathogen physically from spreading through the plant. For example, if you have a long narrow corridor and you put a big obstacle like a giraffe in the middle, people cannot physically move through.

Edit: put too many 'basically's' there oops..just deleted a couple of those to make it better to read
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Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #12820 on: August 02, 2020, 07:30:18 pm »
0
Is this a good summary of DNA replication:
- Helicase unwinds the DNA double helix at the replication fork
- SSBS keep the strands separated
- Polymerase attaches nucleotide at 3 end. Synthesis is in 5 to 3 direction
- Primase synthesises RNA primers
- Each of the two new strands gets synthesised in the 5 to 3 direction
- One new strand is synthesised continuously the other new strand is synthesised discontinuously
- Leading strand is synthesised continuously and the lagging strand is synthesised discontinuously
- Dna pieces separated by rna primers in the lagging strand are Okazaki fragments
- The Rnase H nuclease recognises rna primers bound to DNa and hydrolysed them
- DNA polymerase can then fill in the gaps left by Rnase H
- Ligase joins the short dna pieces together into one continuous strand

1729

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Re: VCE Biology Question Thread
« Reply #12821 on: August 02, 2020, 08:23:27 pm »
+4
Is this a good summary of DNA replication:
- Helicase unwinds the DNA double helix at the replication fork
- SSBS keep the strands separated
- Polymerase attaches nucleotide at 3 end. Synthesis is in 5 to 3 direction
- Primase synthesises RNA primers
- Each of the two new strands gets synthesised in the 5 to 3 direction
- One new strand is synthesised continuously the other new strand is synthesised discontinuously
- Leading strand is synthesised continuously and the lagging strand is synthesised discontinuously
- Dna pieces separated by rna primers in the lagging strand are Okazaki fragments
- The Rnase H nuclease recognises rna primers bound to DNa and hydrolysed them
- DNA polymerase can then fill in the gaps left by Rnase H
- Ligase joins the short dna pieces together into one continuous strand
Yep that is correct, but I was also taught that the DNA polymerase III is the one that attaches nucleotides to the 3' end and DNA polymerase I is the one replaces rna primers with DNA. I think you need to specify that but I'm not sure, I also think you need to know about topoisomerase which is an enzyme that relieves tension in the DNA strand ahead of helicase as the replication fork expands.

Owlbird83

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Re: VCE Biology Question Thread
« Reply #12822 on: August 02, 2020, 08:24:30 pm »
+5
Is this a good summary of DNA replication:
- Helicase unwinds the DNA double helix at the replication fork (not wrong, but I would say 'separates the strands')
- SSBS keep the strands separated No harm adding, but you won't need this much detail (I've never heard of it before)
- Primase synthesises RNA primers I swapped this order
- DNA Polymerase attaches nucleotide at 3 end at RNA primer, and synthesises a complementary strand in 5 to 3 direction
- Each of the two new strands gets synthesised in the 5 to 3 direction
(- One new strand is synthesised continuously the other new strand is synthesised discontinuously) This is a bit repetitive
- Leading strand is synthesised continuously and the lagging strand is synthesised discontinuously
- Dna pieces separated by synthesised from each rna primer in the lagging strand are Okazaki fragments
- The Rnase H nuclease recognises rna primers bound to DNa and hydrolysed them see next point
- DNA polymerase can then fill in the gaps left by Rnase H (I'm not sure you need this much detail in u1/2 (or 3/4), but I could be wrong)
- Ligase joins the short dna pieces DNA fragments together into one continuous strand
I added a few modifications, but I think it was already really good! Good job!

« Last Edit: August 02, 2020, 08:27:08 pm by Owlbird83 »
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ErnieTheBirdi

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Re: VCE Biology Question Thread
« Reply #12823 on: August 05, 2020, 09:34:38 am »
0
Can someone please explain PCR to me? I don't fully understand it and how the splitting and annealing and stuff work?

ErnieTheBirdi

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Re: VCE Biology Question Thread
« Reply #12824 on: August 05, 2020, 12:06:36 pm »
0
Could someone please explain the Gel electrophoresis to me? I watched the edrolo video but I still don't get it , thanks