VCE Biology Question Thread

[solution]

What is X inactivation and is it required for VCE?

Is STR profiling required?

[Calebark]

What is X inactivation and is it required for VCE?

Is STR profiling required?

X Inactivation is not required for VCE, but funnily enough, it was a stem for a multiple choice question in the 2013 exam.

Yes, STR profiling is a part of Tools & Techniques.

Edit: Wait wait, I just checked the study design, I see no mention of STR profiling - perhaps it was just an example for my SAC. The tools & techniques are:

DNA tools and techniques: gel electrophoresis; DNA amplification; DNA sequencing; making a
recombinant plasmid; bacterial transformations; DNA profiling; gene cloning; and using plasmids
as gene delivery systems

[Gogo14]

Some questions I couldn't answer:
1. Describe and explain the role of secondary messengers
2. Photo attached
3. The diference between parallel evolution and convergent evolution
And my own question:
4. Is punk ekk revelant to the course/ exam?

[HasibA]

Some questions I couldn't answer:
1. Describe and explain the role of secondary messengers
2. Photo attached
3. The diference between parallel evolution and convergent evolution
And my own question:
4. Is punk ekk revelant to the course/ exam?

secondary messengers are needed  for things that cant dissolve through a cell membrane, and thus bind to a receptor on the cells membrane surface, causing a secondary messenger to relay that response to the target areas of the cell etc. i dont rmbr well, but its protein-based molecules (i think) that aren't able to pass through, hence need a secondary messanger to relay the signal pathway. [not toooo sure myself, but i tried]

stem cells are generally cells that can be changed into other cells. using that logic, it isn't necessarily somatic cells -  thse cells are more specfically created [if this makes sense]

convergent evolution is organisms have similar structures, which are analogous, and  have a common ancestor. parallel evolution is organisms having traits that evolve independently to that organism. they're very similar, its just that paralle evo. involves the fact that similar characteristics are developed independently [ diff. environments , conditions] (hope i didnt confuse u more xD- main focus is on the independence)

never heard of punk ekk. so id assume not

edit: so many TYPOS AHHA and im bad at explaining, really sorry if i confused u ((

[Butterflygirl]

Guys I need help with the 2004 bio exam 2, question 3 a.

I'm confused because the examiners report says that low levels of phenylalanine would result in low tyrosine and thus, low pigment levels. However, individuals with PKU have the amino acid, phenylalanine but its the enzyme phenylalanine hydroxylase that they don't have. This causes an accumulation of phenylalanine in the body. Also, the question says, "Before treatment" (Treatment = special diet)

So I thought the answer was:

Individuals with PKU do not have the enzyme phenylalanine hydroxylase so the amino acid, phenylalanine cannot be metabolised into tyrosine. Thus, the pigment for hair colour would be produced in small amounts using tyrosine from the diet, causing lighter hair.

Maybe I'm wrong, just need some clarification 

[gameboy99]

Guys I need help with the 2004 bio exam 2, question 3 a.

I'm confused because the examiners report says that low levels of phenylalanine would result in low tyrosine and thus, low pigment levels. However, individuals with PKU have the amino acid, phenylalanine but its the enzyme phenylalanine hydroxylase that they don't have. This causes an accumulation of phenylalanine in the body. Also, the question says, "Before treatment" (Treatment = special diet)

So I thought the answer was:

Individuals with PKU do not have the enzyme phenylalanine hydroxylase so the amino acid, phenylalanine cannot be metabolised into tyrosine. Thus, the pigment for hair colour would be produced in small amounts using tyrosine from the diet, causing lighter hair.

Maybe I'm wrong, just need some clarification 

Perfectly correct answer....good job!!

[Calebark]

4. Is punk ekk revelant to the course/ exam?

Yes, you need to know about punctated equilibrium (long periods of stagnation-->rapid speciation) and gradualism (small, constant changes).

[Mapleflame]

Yes, you need to know about punctated equilibrium (long periods of stagnation-->rapid speciation) and gradualism (small, constant changes).

... I've never heard of them.
Could you please elaborate on what they are?

~A.H

[Butterflygirl]

Another question for bio exam 2, 2004, question 7c.
Is the first band (representing the HbS allele) meant to be the same width in both columns? I drew it as the same width.


Thanks

[Calebark]

... I've never heard of them.
Could you please elaborate on what they are?

~A.H

Sure thing -- they're two competing theories of evolution.

Gradualism Is based upon small, constant change within a species over time. Note that this change within a species is micro-evolution, whereas with many species, it is macro-evolution. An easy way to understand this would be to look at a visual aid.

Punctuated Equilibrium is based upon long periods of rest, with small, rapid intervals of speciation. Again, an easy way to understand this is with another visual aid.

Another question for bio exam 2, 2004, question 7c.
Is the first band (representing the HbS allele) meant to be the same width in both columns? I drew it as the same width.


Thanks

I'll give you my reasoning (that they are different width). I don't know if it'll help, or if it is necessarily correct, so hopefully somebody else may know something.

My reasoning is that HbA/HbS will have 457 base pairs total (227 from HbA, 230 from HbS). As a result, so far, HbS will be first, then HbA closeby. However, HbA has the recognition sequence for MstII, so HbA will be cut into a 52-base and 175-base region, meaning HbS will be on its lonesome, followed by a smaller, 175-base sequence ahead of it, then an even smaller 52-base sequence ahead of that.

So, we have

HbS (230)
HbA (175)

HbA (52)

In the opposite well, we only have HbS/HbS. These are both a 230-base sequence, so they'll travel the same length. However, given this, one will slightly block the other, as they can't occupy the exact same niche, so it'll provide an appear of something bigger. We'd have

HbS (230)

In total, this would make

                                                                              HbS(230)                                                       HbS(230)
HbA(175)

HbA(52)

Quite hope this makes sense, and that I'm not overthinking it, haha.

[Gogo14]

Some questions I couldn't answer:
1. Describe and explain the role of secondary messengers
2. Photo attached
3. The diference between parallel evolution and convergent evolution
And my own question:
4. Is punk ekk revelant to the course/ exam?

Ok cool, but I'm still very confused with 2. And 3.
What does the 2 and 4 embryo cell even mean?

[hodang]

How important or do we have to know about mutations involving sections of chromosomes - Aneuploidy (non-disjunction) and Polyploidy?

[Calebark]

How important or do we have to know about mutations involving sections of chromosomes - Aneuploidy (non-disjunction) and Polyploidy?

We have to know it, but I don't think it's particulary important. From memory, I've only seen it in multiple choice questions.

Ok cool, but I'm still very confused with 2. And 3.
What does the 2 and 4 embryo cell even mean?

2 and 4 cell embryo refers to the stage after fertilisation where the embryo has divided, and reached 2 or 4 cells. At this point, the embryonic stem cells - being stem cells, after all - haven't differentiated and specialised yet. Because of this, they can be used for a variety of different roles. You may have learned about this when you were learning about cloning (think somatic cell nuclear transfer).

[Mapleflame]

Dia duit everyone,
I have compiled a brief summary of the Biology 3/4 notes as part of my revision.
If anyone has the time/willpower to read through them and correct/add parts, that would be absolutely wonderful.
The document may have some format issues, as I had to remove many of the diagrams in order to attach it to this post.
Thank you!
~A.H

[HasibA]

Dia duit everyone,
I have compiled a brief summary of the Biology 3/4 notes as part of my revision.
If anyone has the time/willpower to read through them and correct/add parts, that would be absolutely wonderful.
The document may have some format issues, as I had to remove many of the diagrams in order to attach it to this post.
Thank you!
~A.H

thats actually pretty legit- solid effort! should be set for next year- just glossed over the notes and they're really concise thanks for sharing