Login

Welcome, Guest. Please login or register.

March 29, 2024, 05:20:55 am

Author Topic: VCE Biology Question Thread  (Read 3570818 times)  Share 

0 Members and 10 Guests are viewing this topic.

SmartWorker

  • Forum Obsessive
  • ***
  • Posts: 211
  • Wake determined. Sleep Satisfied.
  • Respect: +79
Re: VCE Biology Question Thread
« Reply #12810 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?
Advice to smash Biology ¾:

2021 VCE - 99.35

Tutoring Bio, Chem, English, Methods 1/2 & 3/4 for 2022. DM if interested

Want some advice for VCE? 👇

https://youtu.be/zq0xsaE9GJ4

Owlbird83

  • BLAA 2020
  • Moderator
  • Forum Leader
  • *****
  • Posts: 553
  • Respect: +785
Re: VCE Biology Question Thread
« Reply #12811 on: August 01, 2020, 10:13:23 am »
+4
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
2018: Biology
2019: Chemistry, Physics, Math Methods, English, Japanese
2020: Bachelor of Psychology (Monash)

SmartWorker

  • Forum Obsessive
  • ***
  • Posts: 211
  • Wake determined. Sleep Satisfied.
  • Respect: +79
Re: VCE Biology Question Thread
« Reply #12812 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!
Advice to smash Biology ¾:

2021 VCE - 99.35

Tutoring Bio, Chem, English, Methods 1/2 & 3/4 for 2022. DM if interested

Want some advice for VCE? 👇

https://youtu.be/zq0xsaE9GJ4

SmartWorker

  • Forum Obsessive
  • ***
  • Posts: 211
  • Wake determined. Sleep Satisfied.
  • Respect: +79
Re: VCE Biology Question Thread
« Reply #12813 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 :)
Advice to smash Biology ¾:

2021 VCE - 99.35

Tutoring Bio, Chem, English, Methods 1/2 & 3/4 for 2022. DM if interested

Want some advice for VCE? 👇

https://youtu.be/zq0xsaE9GJ4

homeworkisapotato

  • MOTM: Aug 20
  • Forum Leader
  • ****
  • Posts: 527
  • Respect: +288
Re: VCE Biology Question Thread
« Reply #12814 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
2020: Biology [43]
2021: Methods, Chemistry, HHD, English, Further
Selective School Entry Tips

Chocolatepistachio

  • Science Games: Silver
  • Forum Obsessive
  • ***
  • Posts: 470
  • Respect: +51
Re: VCE Biology Question Thread
« Reply #12815 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

  • MOTM: July 20
  • Trendsetter
  • **
  • Posts: 185
  • Respect: +158
Re: VCE Biology Question Thread
« Reply #12816 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

  • BLAA 2020
  • Moderator
  • Forum Leader
  • *****
  • Posts: 553
  • Respect: +785
Re: VCE Biology Question Thread
« Reply #12817 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 »
2018: Biology
2019: Chemistry, Physics, Math Methods, English, Japanese
2020: Bachelor of Psychology (Monash)

ErnieTheBirdi

  • Forum Regular
  • **
  • Posts: 75
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #12818 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

  • Forum Regular
  • **
  • Posts: 75
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #12819 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

1729

  • MOTM: July 20
  • Trendsetter
  • **
  • Posts: 185
  • Respect: +158
Re: VCE Biology Question Thread
« Reply #12820 on: August 05, 2020, 12:32:54 pm »
+5
Could someone please explain the Gel electrophoresis to me? I watched the edrolo video but I still don't get it , thanks
This picture might help. So basically, you put your DNA mixture into the wells. The blue stuff is the gel. You turn on the power, and since DNA is negatively charged, the DNA will move towards the positive end. The smaller fragments will travel farther in the gel than the longer fragments, so they get sperated by size.

DNA is overall negatively charged so it moves away from the + from the electrical source. Since all DNA isn't the same size, their ability to pass between the tiny holes in the gel varies. Basically, the small fragments have an easier time to go through the holes than the larger ones, the smaller ones will travel farther down the gel than the longer ones. When fragments stop moving, they cause lines due to the dye, which is what you see in the final gel sample.

If you have any questions don't hesitate to ask! :)

Bri MT

  • VIC MVP - 2018
  • Administrator
  • ATAR Notes Legend
  • *****
  • Posts: 4719
  • invest in wellbeing so it can invest in you
  • Respect: +3677
Re: VCE Biology Question Thread
« Reply #12821 on: August 05, 2020, 04:08:17 pm »
+4
DNA is overall negatively charged so it moves away from the + from the electrical source.

I think you mean away from the negative / towards the +, like you had earlier in your post

It's kind of implicit but the distance stuff is based on the amount of time you have it running for in addition to how fast the DNA fragments travel (which has been correctly pointed out is based on size). This is why you put fragments of known length in to act as a molecular ruler - since the distance will be based on size + the gel + how long the voltage is applied, you need that comparison if you want to know how long your fragments are.

Chocolatepistachio

  • Science Games: Silver
  • Forum Obsessive
  • ***
  • Posts: 470
  • Respect: +51
Re: VCE Biology Question Thread
« Reply #12822 on: August 05, 2020, 04:54:20 pm »
0
Hello
I was having trouble with this question if someone could help me
You are given the task to develop an antiretroviral drug to combat the recently discovered infectious agent know as HIV. You decide to develop a drug that targets an aspect of the HIV life cycle. Which aspect of the HIV cycle would you target and why

-Lilac-

  • Trailblazer
  • *
  • Posts: 40
  • Respect: +38
Re: VCE Biology Question Thread
« Reply #12823 on: August 05, 2020, 05:32:04 pm »
+5
Hello
I was having trouble with this question if someone could help me
You are given the task to develop an antiretroviral drug to combat the recently discovered infectious agent know as HIV. You decide to develop a drug that targets an aspect of the HIV life cycle. Which aspect of the HIV cycle would you target and why

I am not sure if in VCE you go into detail regarding retroviral life cycles (& tbh HIV gets pretty complicated!) so I am going to give some general advice. But let me know if you feel you need more HIV specific advice.

First of all, think about a simple viral lifecycle. The virus gains entry into the cell, replicates inside the cell to high numbers and then viral particles are released to go and infect new host cells. By inhibiting any of those steps you would render that virus unable to complete this life cycle and therefore limiting disease. Could a drug block entry of HIV to the CD4 T cells? Could a drug inhibit viral replication?

Furthermore, you would want to target a part of the viral lifecycle that would not interfere with normal host cell processes. For example, viruses use the host cell ribosome to synthesize critical viral proteins, however,  targeting the ribosome would not be good for the host.
Bachelor of Science (Biochemistry and Immunology)
Honours (Biochemistry and Molecular Biology)

Owlbird83

  • BLAA 2020
  • Moderator
  • Forum Leader
  • *****
  • Posts: 553
  • Respect: +785
Re: VCE Biology Question Thread
« Reply #12824 on: August 05, 2020, 05:34:57 pm »
+4
Hello
I was having trouble with this question if someone could help me
You are given the task to develop an antiretroviral drug to combat the recently discovered infectious agent know as HIV. You decide to develop a drug that targets an aspect of the HIV life cycle. Which aspect of the HIV cycle would you target and why
Hey, I reckon with this question there are likely a few ways you could answer depending on which step of the life cycle you pick to target. I would say target the binding stage with a drug to block the receptors or proteins, which would prevent the virus from being able to enter the cell and hijack it.

Edit: haha Lilac beat me
2018: Biology
2019: Chemistry, Physics, Math Methods, English, Japanese
2020: Bachelor of Psychology (Monash)