Welcome, Guest. Please login or register.

August 23, 2019, 12:44:02 pm

Author Topic: VCE Biology Question Thread  (Read 1308708 times)  Share 

0 Members and 6 Guests are viewing this topic.

PhoenixxFire

  • VIC MVP - 2018
  • Moderator
  • ATAR Notes Superstar
  • *****
  • Posts: 2637
  • Bad puns are how eye roll
  • Respect: +1948
Re: VCE Biology Question Thread
« Reply #10800 on: October 12, 2018, 08:46:46 pm »
+4
Do restriction enzymes cut the hydrogen bonds between nitrogenous bases as well as the covalent bonds in the sugar-phosphate backbone? Just wanted to clarify bc I've read a few sources online where some say restriction enzymes only cut covalent bonds but others say they cut both.
Restriction enzymes only cut the covalent binds, a few hydrogen bonds aren’t strong enough to keep the strands attached so they seperate too. This is also why sticky ends are called sticky - the hydrogen bonds temporarily bind ‘stick’ long enough for ligase to create covalents bonds whereas blunt ends up less likely to be reattached because they won’t join each other.
2019: B Environment and Sustainability/B Science @ ANU

Bell9565

  • Forum Regular
  • **
  • Posts: 93
  • Respect: +36
Re: VCE Biology Question Thread
« Reply #10801 on: October 12, 2018, 09:38:49 pm »
0
Oh okay, i didn't even know they had taken that out of the study design. Thanks heaps though!

Just to clarify, you need to know it in context of glucose in cellular respiration and photosynthesis but not as in the in depth knowledge that used to be taught about carbohydrates (eg the structure of more complex carbohydrates and the level of detail known for proteins)
2017 - Further Mathematics (50), Biology (49)
2018 - English (39), Mathematical Methods (44), Specialist Mathematics (38), Chemistry (50), UMAT (100th)
ATAR - 99.35

galaxy21

  • Trendsetter
  • **
  • Posts: 144
  • Respect: +23
Re: VCE Biology Question Thread
« Reply #10802 on: October 13, 2018, 12:49:58 pm »
0
Hi, so this question came up in the 2015 VCAA biology exam, and I was just wondering if somebody could explain why my answer is incorrect?

The question is (question 7c worth 2 marks)
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.

To answer this, I wrote (and please ignore the terrible wording...)
Alternative Splicing; what one cell produces as growth hormone and another as tryptophan oxygenase may differ as different codons are considered exons and introns in different cells, therefore coding for different amino acid sequences and consequently leading to the production of different proteins with different functions.

The suggested answer in the examiner's report says:
Factors expressed by regulator genes could lead to the production of the different proteins


Would alternative splicing not be a way that the production of distinct proteins in different cell types could happen?
« Last Edit: October 13, 2018, 01:01:50 pm by galaxy21 »
2018 - Biology [38], Further [42]
2019 - English, Chemistry, Methods, Health and Human Development

PhoenixxFire

  • VIC MVP - 2018
  • Moderator
  • ATAR Notes Superstar
  • *****
  • Posts: 2637
  • Bad puns are how eye roll
  • Respect: +1948
Re: VCE Biology Question Thread
« Reply #10803 on: October 13, 2018, 01:02:45 pm »
+6
Hi, so this question came up in the 2015 VCAA biology exam, and I was just wondering if somebody could explain why my answer is incorrect?

The question is (question 7c worth 2 marks)
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.

To answer this, I wrote (and please ignore the terrible wording...)
Alternative Splicing; what one cell produces as growth hormone and another as tryptophan oxygenase may differ as different codons are considered exons and introns in different cells, therefore coding for different amino acid sequences and consequently leading to the production of different proteins with different functions.

The suggested answer in the examiner's report says:
Factors expressed by regulator genes could lead to the production of the different proteins


Would alternative splicing not be a way that the production of distinct proteins in different cell types could happen?
This was actually discussed on here a few weeks ago, pretty sure your answer would be considered correct. In situations like this so long as your answer is reasonable and you've justified why it is correct then you should be fine. I reckon they might actually be referring to alternative splicing when they talk about 'factors expressed by regulator genes'.
2019: B Environment and Sustainability/B Science @ ANU

Sine

  • Moderator
  • ATAR Notes Legend
  • *****
  • Posts: 3450
  • NO ARTWORK 23
  • Respect: +782
Re: VCE Biology Question Thread
« Reply #10804 on: October 13, 2018, 02:11:18 pm »
+2
As the above has stated the possible answers in the biology exam aren't always on the assesors report and many different answers can be accepted for some questions. From memory, the assessor gets a answer key with all the suggested answers however they can also use their own discretion to award marks if the student brings up something that is still correct and makes sense.

Owlbird83

  • Trendsetter
  • **
  • Posts: 187
  • Respect: +164
Re: VCE Biology Question Thread
« Reply #10805 on: October 13, 2018, 04:18:35 pm »
0
Hey,

So I just did the 2015 VCAA biology exam and Question 7 C's answer doesn't make that much sense to me. Only 4% of the state got full marks.

Question:
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.
2 marks

VCAA Answer:
Factors expressed by regulator genes could lead to production of the different proteins.

My thought process was that alternative splicing was involved and different mRNA molecules were produced that lead to different proteins to be produced. In what way do transcription factors lead to different proteins? I thought they either prevented or sped up reactions.

Thanks

I think some are able to fold the proteins in different ways after they are made, creating different shapes.
2018: Biology
2019: Chemistry, Physics, Math Methods, English, Japanese

galaxy21

  • Trendsetter
  • **
  • Posts: 144
  • Respect: +23
Re: VCE Biology Question Thread
« Reply #10806 on: October 13, 2018, 04:19:33 pm »
0
Hey,

So I just did the 2015 VCAA biology exam and Question 7 C's answer doesn't make that much sense to me. Only 4% of the state got full marks.

Question:
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.
2 marks

VCAA Answer:
Factors expressed by regulator genes could lead to production of the different proteins.

My thought process was that alternative splicing was involved and different mRNA molecules were produced that lead to different proteins to be produced. In what way do transcription factors lead to different proteins? I thought they either prevented or sped up reactions.

Thanks
Look just up the page... I just asked the exact same question haha.  ;D
2018 - Biology [38], Further [42]
2019 - English, Chemistry, Methods, Health and Human Development

passbleh24

  • Trailblazer
  • *
  • Posts: 46
  • Respect: +2
Re: VCE Biology Question Thread
« Reply #10807 on: October 13, 2018, 04:26:14 pm »
+1
Look just up the page... I just asked the exact same question haha.  ;D

Oh wow, I didn't notice at all !!! I thought the chances of someone asking the same question was low, posting without checking. I'll delete my double question then.

Edit: our thought process was similar too....
« Last Edit: October 13, 2018, 04:28:37 pm by passbleh24 »

Owlbird83

  • Trendsetter
  • **
  • Posts: 187
  • Respect: +164
Re: VCE Biology Question Thread
« Reply #10808 on: October 13, 2018, 05:31:36 pm »
0
What score would I need to get on the exam to get over 45? I am ranked around 3 to 5ish  in my cohort, (its a weak cohort, they said they only expect about 3 scores over 40 for bio)
What scores were/are you guys getting on your practice exams?
For my practice, internal exam I got 88%, and probably similar on other practice exams.
2018: Biology
2019: Chemistry, Physics, Math Methods, English, Japanese

Sine

  • Moderator
  • ATAR Notes Legend
  • *****
  • Posts: 3450
  • NO ARTWORK 23
  • Respect: +782
Re: VCE Biology Question Thread
« Reply #10809 on: October 13, 2018, 05:34:51 pm »
+1
What score would I need to get on the exam to get over 45? I am ranked around 3 to 5ish  in my cohort, (its a weak cohort, they said they only expect about 3 scores over 40 for bio)
What scores were/are you guys getting on your practice exams?
For my practice, internal exam I got 88%, and probably similar on other practice exams.
88% is probably around what you want to be getting (although that's assuming that was an VCAA exam)

/120 you'd probably want  something like 105-110/120 depending on difficulty. With your rank you would need higher imo.

missile

  • Adventurer
  • *
  • Posts: 10
  • Respect: 0
Re: VCE Biology Question Thread
« Reply #10810 on: October 13, 2018, 06:44:26 pm »
0
Hi
I just wanted to clarify:
1. Is the Golgi apparatus involved in transport of proteins both for use by the cell and export from the cell?
2. What is the pathway for a protein for use by the cell, which I understand would be synthesised at a free ribosome?
3. Which pathway would cell membrane proteins be transported via?

Thank you very much
2018: Biology [50]
2019: English Language, Methods, Specialist, Chemistry, French

Owlbird83

  • Trendsetter
  • **
  • Posts: 187
  • Respect: +164
Re: VCE Biology Question Thread
« Reply #10811 on: October 13, 2018, 08:56:32 pm »
0
88% is probably around what you want to be getting (although that's assuming that was an VCAA exam)

/120 you'd probably want  something like 105-110/120 depending on difficulty. With your rank you would need higher imo.

Thank you!
2018: Biology
2019: Chemistry, Physics, Math Methods, English, Japanese

Azim.m

  • Forum Regular
  • **
  • Posts: 64
  • Respect: +1
VCE Biology Question Thread
« Reply #10812 on: October 13, 2018, 10:14:43 pm »
0
Question: give two reasons why the degree of DNA homology is a more accurate measure of relatedness between species than protein homology?
Would I be correct if I said...
-DNA homology contains non coding regions that generally are more reliable because they’re not subject to natural selection, unlike protein homology
-DNA homology is able to show almost all mutations in the DNA sequence, whereas the mutations in proteins aren’t as apparent because more than one codon can code for the same amino acid
« Last Edit: October 13, 2018, 10:52:54 pm by Azim.m »

PhoenixxFire

  • VIC MVP - 2018
  • Moderator
  • ATAR Notes Superstar
  • *****
  • Posts: 2637
  • Bad puns are how eye roll
  • Respect: +1948
Re: VCE Biology Question Thread
« Reply #10813 on: October 13, 2018, 11:02:43 pm »
+3
Hi
I just wanted to clarify:
1. Is the Golgi apparatus involved in transport of proteins both for use by the cell and export from the cell?
2. What is the pathway for a protein for use by the cell, which I understand would be synthesised at a free ribosome?
3. Which pathway would cell membrane proteins be transported via?

Thank you very much
1. Just export
2. You don't need to know this, the study design specifies that you need to know the path for export
Spoiler
•    the role of different organelles including ribosomes, endoplasmic reticulum, Golgi apparatus and associated
vesicles in the export of a protein product from the cell through exocytosis
3. I believe export (they'd be in the membrane of the vesicle which would then fuse with the cell membrane). But you don't need to know for VCE.

Question: give two reasons why the degree of DNA homology is a more accurate measure of relatedness between species than protein homology?
Would it be correct if I said...
-DNA homology contains compares non coding regions that generally are more reliable contain more variation between species because they’re not subject to natural selection, unlike protein homology
-DNA homology is able to show almost all mutations in the DNA sequence, whereas the mutations in proteins aren’t as apparent because more than one codon can code for the same amino acid
For the first part I would say something about more variation being present in those areas due to the absences of natural selection pressures rather than calling them more reliable. It's kind of missing context otherwise, more reliable than what? reliable in what way?

For the second one I would use a bit more precise language, 'almost all' and 'aren't as apparent' kind of make it seem as though you only sort of understand what you're talking about. When jargon is available for these things then try and use it - it's sort of just showing off what you know (having said that, don't use it incorrectly!) So I would say something like
'DNA homology can be used to compare individual DNA bases whereas protein morphology can only be used to compare codons, therefore DNA homology will show more differences between species than protein morphology and therefore be a more accurate reflection of species' genetic similarity.'

Having said that, I'm being super picky here haha, your answers are correct as they are :)
2019: B Environment and Sustainability/B Science @ ANU

PopcornTime

  • Forum Obsessive
  • ***
  • Posts: 264
  • Respect: +10
Re: VCE Biology Question Thread
« Reply #10814 on: October 14, 2018, 09:36:27 am »
0
Describe the out of Africa hypothesis:
- Homo Erectus migrated out of Africa and spread across the world
- Homo sapiens evolved from a hominin population in Africa and then migrated out of Africa

Describe the multi regional hypothesis:
- Homo Erectus migrated out of Africa and different populations of Homo Erectus became genetically isolated from each other
- Homo sapiens simultaneously evolved from different populations of Homo Erectus around the world

What else could I include in the above explanations if it was a 3-4 mark question?