VCE Biology Question Thread

[areeb008]

Thanks! Just a couple of things with regards to trends in hominin evolution:
what was the main cause/selection pressure acting on hominins that resulted in their increase in cranial capacity and a flatter face?

[vox nihili]

Thanks! Just a couple of things with regards to trends in hominin evolution:
what was the main cause/selection pressure acting on hominins that resulted in their increase in cranial capacity and a flatter face?

What do you think? Good opportunity to have a bit of a stab before someone tells you

[LifeisaConstantStruggle]

Thanks! Just a couple of things with regards to trends in hominin evolution:
what was the main cause/selection pressure acting on hominins that resulted in their increase in cranial capacity and a flatter face?

There are several factors (selection pressures) to this change in the cranial capacity of hominins actually, which include predators and food and the requirement of having the brainpower to make tools to fend off these predators/catch prey.

[areeb008]

What do you think? Good opportunity to have a bit of a stab before someone tells you

for cranial capacity i would have thought it increases as a result of increasing competition for resources which means those with larger brains (corresponding to more intelligence) would have higher chances of survival, but I feel like I'm missing something. For the flattening of the face i honestly have no idea haha.

[PhoenixxFire]

The flattening of the face could be due to better visibility but it's generally just assumed it was a side effect of an increasing cranial volume.

[TheBigC]

The binding directly to the gene element tells you a little bit about why they don’t get broken down as quickly (because they’re still needed), but it doesn’t explain why the responses are different speeds.

Thanks Lifeisaconstantstruggle for quoting what I’d said previously handy not to have  explain things again and it can be hard scrolling through old messages!

Just adding to the already good discussion here: (This is from a VCE standpoint and the expected level of understanding required (at least I would assume based on some past VCAA exams))

1. The reason that the duration of the response in hydrophobic signalling pathways is longer than that in hydrophilic signalling pathways is due to the hydrophobic hormone-receptor complex promoting the transcription of a specific gene. Ultimately, this results in the synthesis of mRNA, in which can be translated MULTIPLE times over, producing many identical proteins until the mRNA itself degrades. This is unlike with hydrophilic signalling molecules which merely ACTIVATE (or inactivate depending on the specific response) already present cellular proteins - where these proteins are active for some time... then degrade and response ends... etc.
2. The reason the speed of the response in the hydrophilic signalling pathway is FASTER is due to the fact that hydrophilic signalling molecules only need to activate a specific cellular molecule (etc.) - key word 'ACTIVATE'. However, in the latter hydrophobic signalling pathway, the process of gene transcription, post-transcriptional modification, translation THEN response must occur, a much lengthier process per se.

[helpmepls112]

Can someone please give me a definition to vaccine?
And a simplified explanation of all the types of vaccines that are available? (eg attenuated etc.)

Thank you

[ImmaculateJeff]

Can someone please give me a definition to vaccine?
And a simplified explanation of all the types of vaccines that are available? (eg attenuated etc.)

Thank you

A vaccine is an antigenic substance made from the disease causing agent to provides immunity against that specific disease. It is usually made up of an altered, weakened or killed microorganism or inactivated forms forms of toxins or antigens.

Live attenuated vaccine
Involves a living microbe that has been weakened in the lab, usually through repeated culturing
Inactivated vaccine
Also known as 'killed vaccines', contain microbes inactivated by heat/radiation/chemicals
Subunit vaccines
Dont contain any live microbial components, only haveparts of microbes selected for their ability to induce an adaptive immune response.
Toxoid vaccines
are non-recombinant subunit vaccines that use toxins inactivated by toxoids.

[M-D]

Hi all,

What about neurons do we need to know for the exam? Is knowledge of depolarization, action potentials etc. required?

Thanks

[PhoenixxFire]

Specific details are no longer required but you should know how neurotransmitters are released as how they attatch to the postsynsptic neuron

[LPadlan]

Hey, does anyone have notes on specific restriction enzymes such as Aha I? eg. How many fragments they cut, where they cut. If this is not relevant to study design(we had a sac on this, but im missing my notes) then don't worry about it, thanks.

[PhoenixxFire]

The study design just mentions restriction enzymes and doesn't go into any detail so I don't think we will need to know that much specific information. The dot point says:
- the use of enzymes including endonucleases (restriction enzymes), ligases and polymerases

[LifeisaConstantStruggle]

Hey, does anyone have notes on specific restriction enzymes such as Aha I? eg. How many fragments they cut, where they cut. If this is not relevant to study design(we had a sac on this, but im missing my notes) then don't worry about it, thanks.

I'll just add to a bit more than what is mentioned above.
We are not required to remember specific restriction enzymes, but it can be assessed in the exam (take VCAA sample exam for example). They can give us examples of specific restriction enzymes (Alu I, Aha I, etc) and their recognition site in the question and ask us to answer questions from there.

[ezferns]

Can someone pls explain Q8c vcaa ex2 2015?
Why can't stratigraphy be used to date the fossils?

[PhoenixxFire]

Are you sure that's the right year I can't find the question?