VCE Biology Question Thread

[PhoenixxFire]

^IMO they messed up the solutions for that question. I'd agree that it should show the bamHI recognition sites - there'd be two because that's where it cut so they'd be at either end of the human gene. The recognition site wouldn't be destroyed - the gene being put into it would have been cut with the same restriction enzyme which is what makes the ends complementary.

They stated the 'position' of it so they are purely trying to ask where that gene of interest is being inserted into, not to simply label BamHI.

It's included in the same sentence about the other recognition sites and they're labelled in the solution.

[whys]

Hello guys, can anyone clarify why the answer diagram for 9bii on the VCAA 2017 exam doesn't include the restriction sites for BamHI, even though the question specifically asked to 'include the position of the recognition sites for the restriction enzymes EcoRI, HindIII, and BamHI on the plasmid'? Should it be assumed that the recognition site is destroyed when cut by BamHI? Thanks

My teacher (who marked the 2017 exam) said that students did so poorly on this question that they had to accept diagrams without the BamHI labelled even though it was required. It's important to remember that examiners reports do not always give us the best possible answer, nor do they give us all the possible answers.

[miyukiaura]

Do amino acids move across the membrane through channel proteins or carrier proteins?

[homeworkisapotato]

I'd say it can be both. Amino acids can passively diffuse through both but in terms of active transport they would go through carrier proteins

[ActivationEnergy]

Can glucose travel across the membrane via facilitated diffusion AND active transport or is it just one of the two?Different sources are giving me different answers.

[whys]

Can glucose travel across the membrane via facilitated diffusion AND active transport or is it just one of the two?Different sources are giving me different answers.

I believe it can be either, depending on whether it's travelling along or against the concentration gradient. It will depend on the scenario the question gives.

[Sine]

Can glucose travel across the membrane via facilitated diffusion AND active transport or is it just one of the two?Different sources are giving me different answers.

As whys said it can be both, it depends on the type of cell, type of transporter proteins that the cell is expressing at a given time, glucose concentrations inside and outside of the cell, sometimes other ion concentrations have an impact as well

[Moonblossom]

Hey. I don't really get the difference between limitations and errors. Could anyone please provide some examples?
Thank you!

[darkz]

Hey. I don't really get the difference between limitations and errors. Could anyone please provide some examples?
Thank you!

Limitations refer to problems with the method itself, while errors refer to problems when conducting the experiment. However, these can also overlap. For example, if there was a photosynthesis experiment where people had to read a pH indicator, a limitation would be the subjective nature of the experimental measure, which would also constitute a systematic error as the person may consistently read it as a higher pH or vice versa. A case where it would only be an error and not a limitation could include the miscalibration of a scale (systematic error).

[miyukiaura]

Would complement proteins lyse viruses or would they neutralise them by blocking their antigens so they are unable to infect body cells? thanks!

[darkz]

Would complement proteins lyse viruses or would they neutralise them by blocking their antigens so they are unable to infect body cells? thanks!

Through a membrane attack complex, complement proteins could lyse virally infected cells. Likewise, they can opsonise pathogens/virally infected cells, preventing them from infecting other cells and increase phagocytosis. If you're referring to extracellular viral particles, lysis is not applicable since they're not really considered cells - more like a particle.

[homeworkisapotato]

Hey! I heard that the psych exam was super hard, way harder than the previous years and now I'm really scared of the Bio exam tomorrow. Like I keep thinking what if the difficulty level is super high and I won't do well, and I'm kinda freaking out. Any advice?

[tigerclouds]

Hey guys, can someone explain how a wide pelvis, S-shaped spine and a carrying angle indicate that an organism is bipedal. I'm also confused as to how evidence can be used to support the Out of Africa hypothesis, could someone please explain what types of evidence can be used to explain it and how?

[homeworkisapotato]

Hey guys, can someone explain how a wide pelvis, S-shaped spine and a carrying angle indicate that an organism is bipedal. I'm also confused as to how evidence can be used to support the Out of Africa hypothesis, could someone please explain what types of evidence can be used to explain it and how?

Wide pelvis: because it's short and wide, it can support the weight of the upper body while allowing free locomotion of the legs
S-shaped spine: similar to pelvis, allows the weight of the upper body to be distributed evenly

Evidence for Out of Africa hypothesis: If the oldest hominin fossil is found in Africa that suggests that hominins had originated in africa and then migrated out. Also, if Africans have a larger genetic variation to the rest of us, that's essentially an example of founder's effect. As a small amount of population of hominins moved OUT of Africa and interbred over time with each other, more genetic differences accumulated between Africans and the rest of us.

Hope that helped!!

[whys]

Hey! I heard that the psych exam was super hard, way harder than the previous years and now I'm really scared of the Bio exam tomorrow. Like I keep thinking what if the difficulty level is super high and I won't do well, and I'm kinda freaking out. Any advice?

Best you can do is keep calm. From my friends I've heard it was a similar difficulty to the 2019 psych exam, and both have moved to more application-style questions. From what I've seen, you've practised so much and I believe in you to do well. Don't worry, try some breathing techniques or meditation - at this point, it's your mindset that matters. A positive outlook will do you wonders in the exam than if you begin to panic. They will not make the exam inaccessible. It will still be doable, VCAA are not monsters (well, maybe they are, but they aren't going to make the exam insanely difficult).

All the best!