Welcome, Guest. Please login or register.

October 21, 2019, 01:51:59 am

Author Topic: VCE Biology Question Thread  (Read 1385013 times)  Share 

0 Members and 11 Guests are viewing this topic.

PhoenixxFire

  • VIC MVP - 2018
  • Moderator
  • ATAR Notes Superstar
  • *****
  • Posts: 2778
  • Bad puns are how eye roll
  • Respect: +2082
Re: VCE Biology Question Thread
« Reply #10725 on: October 02, 2018, 12:41:09 pm »
+7
Few questions:
1. What's the difference between protein-based and peptide-based hormones?
2. What does the "recycling of cell debris" stage of apoptosis comprise of?
3. What is the final stage of apoptosis? Signal for macrophages? Cell fragments into apoptotic bodies?
4. Does light energy excite electrons in the ETC of light dependent stage, or is it only used for photolysis?
5. What are "prominent heelbones" and how do they provide a selection advantage?
6. What's the difference between clonal selection and expansion?
7. For inflammation, doesn't vasodilation DECREASE blood pressure? So why is there an increased blood flow?

Thanks so much!
1. Protein based hormones have longer amino acid chains than peptide-based hormones. You don't need to distinguish between them for VCE though, you just need to know that some hormones are amino-acid based (amine, peptide, protein) and some are steroid based.

2. Not really sure on this. I think it just means that after blebs have been phagocytosed the individual components are reused in the body. Not sure whether they would be broken down into base components or entire organelles reused or what though.

3.
According to VCAA 2016
Quote from: Q3.c.
As a wound heals, cells that are no longer needed for the healing process are removed by apoptosis.
Apoptosis is stimulated by external cell signalling from cells such as cytotoxic T cells (Tc).
    Outline the main stages in cell apoptosis once stimulated by the Tc cells.

Quote from: suggested solutions
Possible answers included:
• enzymes; for example, caspases are activated within the cell
• digestion of cell contents
• cell shrinkage
• cell blebbing
• cell breaks up
• cell signals macrophages.
Phagocytosis of cell debris was not accepted.
So I'd take this to mean that VCAA believes 'signal for macrophages' is the last step.

4. Haven't got a clue. Definitely not something you need to know for VCE though.

5. Prominent heelbones refers to your heel sticking out. Like if you point your toes you have a bump where your heel is. The selection advantage is that they make bipedalism more efficient and does a better job of supporting the increased weight associated with bipedalism & evolution.

6. Clonal selection is when a B or T cell is activated. Clonal expansion is when it multiplies producing lots and lots of identical daughter cells.

7. Vasodilation does decrease blood pressure but there'll be more blood in the area at any one time because the capillaries are bigger (also it makes it more permeable, which allows white blood cells to cross the membrane as peter.g15 said)



Is enzyme optimal temperature an example of natural selection?

- so only organisms with correct enzyme optimal temperature survived, reproduced, passed on favourable alleles to offspring

Am I overthinking this or would this be correct?
Purely speculation, but given the importance of enzymes I'd imagine that a mutation that resulted in an enzyme functioning less efficiently would probably result in the death of that individual. So in a way yes it would be natural selection. Probably not something you'll ever have to talk about for VCE though haha
2019: B Environment and Sustainability/B Science @ ANU

$noopDodd

  • Adventurer
  • *
  • Posts: 23
  • Respect: +3
Re: VCE Biology Question Thread
« Reply #10726 on: October 02, 2018, 03:43:06 pm »
0
2015, Q7C
In the rat pituitary gland, GC stimulates the production of the growth hormone protein, However, in the rat liver, GC stimulates the production of the enzyme tryptophan oxygenase. Given that the genetic sequence is identical in all somatic rat cells, explain how the production of distinct proteins in different cell types could occur.

The answer is: Factors expressed by regulator genes could lead to the production of the different proteins

Could someone please explain what the factors expressed by regulator genes actually are? And would exon juggling/ alternative splicing be considered a valid answer?

I feel like the mean something similar to transcriptional factors. I emailed my teacher about this question too and she said that the old study design didn't have an emphasis on the stuff we do now. So, i think exon juggling could be considered a valid answer IMO. I think if it's reasonably justified and correct in terms of your knowledge, you should get the marks. The examiners reports don't list out all the potential solutions :)

Would the following be a valid answer for this question?
-Different receptors/second messengers in the two cells leading to different signal transduction pathways
-therefore different genes are activated, producing two distinct proteins
2018: Biology [44]
2019: English, Mathematical Methods, Specialist Mathematics, Chemistry, MUEP Chem

juntyhee

  • Adventurer
  • *
  • Posts: 23
  • Respect: +5
Re: VCE Biology Question Thread
« Reply #10727 on: October 02, 2018, 11:49:04 pm »
0
1. Protein based hormones have longer amino acid chains than peptide-based hormones. You don't need to distinguish between them for VCE though, you just need to know that some hormones are amino-acid based (amine, peptide, protein) and some are steroid based.

2. Not really sure on this. I think it just means that after blebs have been phagocytosed the individual components are reused in the body. Not sure whether they would be broken down into base components or entire organelles reused or what though.

3.
According to VCAA 2016So I'd take this to mean that VCAA believes 'signal for macrophages' is the last step.

4. Haven't got a clue. Definitely not something you need to know for VCE though.

5. Prominent heelbones refers to your heel sticking out. Like if you point your toes you have a bump where your heel is. The selection advantage is that they make bipedalism more efficient and does a better job of supporting the increased weight associated with bipedalism & evolution.

6. Clonal selection is when a B or T cell is activated. Clonal expansion is when it multiplies producing lots and lots of identical daughter cells.

7. Vasodilation does decrease blood pressure but there'll be more blood in the area at any one time because the capillaries are bigger (also it makes it more permeable, which allows white blood cells to cross the membrane as peter.g15 said)


Purely speculation, but given the importance of enzymes I'd imagine that a mutation that resulted in an enzyme functioning less efficiently would probably result in the death of that individual. So in a way yes it would be natural selection. Probably not something you'll ever have to talk about for VCE though haha

Thanks so much!!
2018 - Biology [48]

PhoenixxFire

  • VIC MVP - 2018
  • Moderator
  • ATAR Notes Superstar
  • *****
  • Posts: 2778
  • Bad puns are how eye roll
  • Respect: +2082
Re: VCE Biology Question Thread
« Reply #10728 on: October 03, 2018, 12:57:06 pm »
+3
Would the following be a valid answer for this question?
-Different receptors/second messengers in the two cells leading to different signal transduction pathways
-therefore different genes are activated, producing two distinct proteins
Given the additional information given at the beginning of question 7 and given that part C. refers to the genetic sequence being identical, I would say no.
If the question was more generically referring to how one hormone can cause different responses in different cells then yes your answer would be correct, but in this case it's specifically referring to how one gene can produce more than one protein.
2019: B Environment and Sustainability/B Science @ ANU

PopcornTime

  • Forum Obsessive
  • ***
  • Posts: 264
  • Respect: +10
Re: VCE Biology Question Thread
« Reply #10729 on: October 03, 2018, 01:14:18 pm »
0
why would it be important to have positive and negative regulators in signalling pathways?
- prevent overreaction by the cell and thus, conserve energy

Thoughts?

PopcornTime

  • Forum Obsessive
  • ***
  • Posts: 264
  • Respect: +10
Re: VCE Biology Question Thread
« Reply #10730 on: October 03, 2018, 02:39:30 pm »
0
Is the following correct?

Physical barriers:
- intact skin
- ear wax

Chemical barriers:
- stomach acid
- lysozyme in tears
- fatty acids on skin

Microbiological barriers:
- natural flora
- expulsion reflexes (sneezing, etc.)
- ciliated lining
« Last Edit: October 03, 2018, 02:42:14 pm by PopcornTime »

Qwerty1234qwerty

  • Adventurer
  • *
  • Posts: 18
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #10731 on: October 03, 2018, 07:23:40 pm »
0
Can someone please explain to me why not finishing a course of antibiotics contributes to antibiotic resistance?

peachxmh

  • Forum Regular
  • **
  • Posts: 84
  • ¯\_(ツ)_/¯
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #10732 on: October 03, 2018, 08:08:34 pm »
0
Still a little confused about MHC markers so I wanted to clear something up - are MHC markers only present on human cells or do other pathogens (e.g. virus, bacteria) have MHC markers? Also to summarise the recognition of self-antigens, would it be correct to say that B and T cells, and also APCs recognise the markers (would this only be MHC-I markers?) on cells as self if they have the same markers as themselves? Thank youuuu!
2018: Biology [45]
2019: Chemistry [ ] English [ ] Methods [ ] Revolutions [ ] French [ ]

"Strive for progress, not perfection"

vox nihili

  • National Moderator
  • Great Wonder of ATAR Notes
  • *****
  • Posts: 5286
  • Respect: +1366
Re: VCE Biology Question Thread
« Reply #10733 on: October 03, 2018, 08:50:49 pm »
+5
Can someone please explain to me why not finishing a course of antibiotics contributes to antibiotic resistance?

Bacteria can be partially resistant to antibiotics, meaning that the antibiotics aren't quite as effective as they would normally be. So if you only use half the course, you only half kill the bacteria, and then the partially resistant bacteria grow back and then constitute the bacteria that get passed around, then they can evolve to become fully resistant.
MED INTERVIEW TUTORING PM to secure your place early, as they fill up quickly!

Join ATARNotes Footy Tipping

2013-15: BBioMed (Biochemistry and Molecular Biology), UniMelb
2016-20: MD, UniMelb
2019: MPH, UniMelb
Year I: BIOL10002 BIOL10003 CHEM10006 MAST10011 MAST10016 PHYC10007 SPAN10001 SPAN10002
Year II: BCMB20005 BIOM20001 BIOM20002 CLAS10022 GENE20001 SPAN20020 SPAN30014
Year III: BCBM30001 BCMB30002 BCMB30010 BIOM30001 BIOM30002 PHRM30008

darkz

  • MOTM: APR 18
  • Forum Obsessive
  • ***
  • Posts: 283
  • Respect: +95
Re: VCE Biology Question Thread
« Reply #10734 on: October 03, 2018, 09:17:13 pm »
+5
Is the following correct?

Physical barriers:
- intact skin
- ear wax

Chemical barriers:
- stomach acid
- lysozyme in tears
- fatty acids on skin

Microbiological barriers:
- natural flora
- expulsion reflexes (sneezing, etc.)
- ciliated lining

Yeh looks good  ;)

Still a little confused about MHC markers so I wanted to clear something up - are MHC markers only present on human cells or do other pathogens (e.g. virus, bacteria) have MHC markers? Also to summarise the recognition of self-antigens, would it be correct to say that B and T cells, and also APCs recognise the markers (would this only be MHC-I markers?) on cells as self if they have the same markers as themselves? Thank youuuu!

MHC markers are only present in vertebrates, so no, they would not be present in pathogens. As for the recognition of self markers, I'm pretty sure that most of the immune cells can do this, e.g. if a macrophage comes across a cell with self markers, then its not going to eat it. The same logic here also applies to APCs, T and B cells. As for the MHC markers, MHC Class I markers are used to distinguish between self and non-self, while the MHC Class II markers are for the professional APCs to present the antigen on
2018: Biology [50 + Prems], Mathematical Methods
2019: English, Latin, Chemistry, Specialist Mathematics

EllingtonFeint

  • Trendsetter
  • **
  • Posts: 146
  • Respect: +21
Re: VCE Biology Question Thread
« Reply #10735 on: October 04, 2018, 09:23:46 am »
0
Could somebody please help me!!
This is my first time ever posting on here and I am so confused about this noe bio question.
So for the 2017 VCAA Bio exam, multiple choice questions 38 and 39 have got me so utterly baffled.
Could somebody please explain them to me. I have no idea what’s happening with these two questions and UGH so confused. Any help would be greatly appreciated :)

I’ve attached the questions too BTW :)

Thank youuuuu
2018: Biology 🌱 [49] |  Second Language: [40]

Offering biology tutoring! PM for details.

Surviving and Succeeding in Biology:
https://atarnotes.com/forum/index.php?topic=187145.msg1129188#msg1129188

PhoenixxFire

  • VIC MVP - 2018
  • Moderator
  • ATAR Notes Superstar
  • *****
  • Posts: 2778
  • Bad puns are how eye roll
  • Respect: +2082
Re: VCE Biology Question Thread
« Reply #10736 on: October 04, 2018, 09:52:08 am »
+3
Could somebody please help me!!
This is my first time ever posting on here and I am so confused about this noe bio question.
So for the 2017 VCAA Bio exam, multiple choice questions 38 and 39 have got me so utterly baffled.
Could somebody please explain them to me. I have no idea what’s happening with these two questions and UGH so confused. Any help would be greatly appreciated :)

I’ve attached the questions too BTW :)

Thank youuuuu

Hey, welcome to AN ;D

38. So this question is testing that you know how restriction enzymes and gel electrophoresis works.

So to start with, use row T. Row T only has two DNA fragments. In the answers table we can see that HaeIII, SaII, and BamI are the possible restriction enzymes that could have cut that fragment. Of those 3 restriction enzymes, HaeIII is the only one that has a single cut site drawn on the DNA strand above. This means that it is the only one that could have resulted in two DNA fragments (the rest would have resulted in 3). So now we know that the answer must be A or B

So then we use row U. Only options A or B on the table could have cut the DNA fragment. So it must be either BamH1 or Sall. Looking at the DNA fragment above, we can we that Sall would result in 1 short piece and 2 longer pieces, as seen on the gel electrophoresis in row U whereas Sall would result in two short pieces and one longer piece. Therefore it must have been Sall that cut this DNA fragment (option B). Therefore we now know that the answer is option B (you can also double check that option B also works for rows R and S).

39. I've attached this. Let me know if it doesn't make sense.




Still a little confused about MHC markers so I wanted to clear something up - are MHC markers only present on human cells or do other pathogens (e.g. virus, bacteria) have MHC markers? Also to summarise the recognition of self-antigens, would it be correct to say that B and T cells, and also APCs recognise the markers (would this only be MHC-I markers?) on cells as self if they have the same markers as themselves? Thank youuuu!
MHC markers are only present in vertebrates, so no, they would not be present in pathogens. As for the recognition of self markers, I'm pretty sure that most of the immune cells can do this, e.g. if a macrophage comes across a cell with self markers, then its not going to eat it. The same logic here also applies to APCs, T and B cells. As for the MHC markers, MHC Class I markers are used to distinguish between self and non-self, while the MHC Class II markers are for the professional APCs to present the antigen on
Just wanted to add to this, immune cells don't really detect 'self', self is the absence of non-self (at least for VCE). Also I'm not sure if it's just the way you worded the question or not - It's not MHC that determines if a cell is infected by a pathogen - it's the peptide fragments presented on the MHC. (Although variations in MHC can indicate cancer and can cause tissue rejection in the case of transplants).

Peptide fragments produced within a cell are presented on MHC 1 - if the cell is infected with a virus then the cell will be making foreign peptides. If a Tc cell can bind to this fragment, it means that the fragment is non-self and therefore that the cell is infected.

From discussions on here in the past I'm pretty sure that immune cells can recognise some self markers, but for the purpose of VCE, an immune cell recognises something as self by being unable to bind to the antigen presented (e.g. on MHC1, i.e. the absence of non-self particles)
« Last Edit: October 04, 2018, 10:37:46 am by PhoenixxFire »
2019: B Environment and Sustainability/B Science @ ANU

galaxy21

  • Trendsetter
  • **
  • Posts: 148
  • Respect: +23
Re: VCE Biology Question Thread
« Reply #10737 on: October 04, 2018, 03:57:11 pm »
0
Hi just wondering, with plant hormones, which ones do we need to know about? Do we need to know if they bind to intracellular or extracellular receptors in cells?
2018 - Biology [38], Further [42]
2019 - English, Chemistry, Methods, Health and Human Development

Scribe

  • Forum Regular
  • **
  • Posts: 69
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #10738 on: October 04, 2018, 05:42:45 pm »
0
Hi! I have a couple of questions regarding transcription factors.

1) What are transcription factors?
2) Are transcription factors coded for by regulatory genes?
3) Are repressors transcription factors? If not, where do repressors/transcription factors come from?
4) Where do transcription factors bind? Do they bind to the promoter, operator, repressor etc. ?

Thanks!

galaxy21

  • Trendsetter
  • **
  • Posts: 148
  • Respect: +23
Re: VCE Biology Question Thread
« Reply #10739 on: October 04, 2018, 08:05:02 pm »
0
Hi!
Can somebody please explain the difference between gram negative and gram positive bacteria? Do we need to know this for the study design?
Thanks ;)
2018 - Biology [38], Further [42]
2019 - English, Chemistry, Methods, Health and Human Development