VCE Biology Question Thread

[Ahmad_A_1999]

I'm not 100% sure so please anyone feel free to correct me.
The experiments purpose is to investigate the effect of pH on enzyme activity not how a pH change can break down the cloudy suspension. While pH is part of the experiment it is not meant to be the thing breaking down the cloudy suspension but rather increasing or decreasing enzyme activity. Therefore the control without the enzymes ensures that the pH is not responsible for the breakdown and thus the enzyme is breaking it down. This assists the experiment as it is known for sure whether or not the enzyme is doing all of the breaking down and if it is we can conclude that the pH is then only responsible for increasing/decreasing enzyme activity (the aim of the experiment).

Perfect! Thanks so much!

[psychologie]

'only 1 strand contains bases coding for characteristics' is this strand the template/anti-sense/non-coding strand or the non-template/sense/coding strand?

 tia

[cookiedream]

'only 1 strand contains bases coding for characteristics' is this strand the template/anti-sense/non-coding strand or the non-template/sense/coding strand?

 tia

That's the template strand

[psychologie]

That's the template strand

thank you! why on earth would they call it the non-coding strand haha. so confusing

[ImmaculateJeff]

Is all the stuff in the atar notes bio book the only things we have to know or are there any additional stuff?

[vcestressed]

Is all the stuff in the atar notes bio book the only things we have to know or are there any additional stuff?

I think the notes are supposed to be used as a supplement to your textbooks. I think most of the info is in the notes but def look at your textbook to make sure you haven't missed out in learning anything important

[vox nihili]

Hi there! I would really appreciate it if someone could help me out with the following questions mainly about gene expression

1. are homeotic genes the same as regulatory genes?
2. the start/stop triplets in a gene, are they exons? are they part of the coding region of DNA or not?
3. in prokaryotes, one promoter codes for multiple genes and in eukaryotes, one promoter codes for one gene. is this correct?
4. substation point mutation: when one nucleotide is replaced with another nucleotide of the same genetic materials (what does ‘of the same genetic materials’ mean?)
5. is the operator region of a gene considered a regulatory gene?
6. 'regulatory genes produce transcriptional factors/RNA that control the expression of other genes'. if this is correct, how does RNA control expression of genes? i thought it was just the repressor/activator PROTEINS
7. is it correct to say ‘lactose binds NON-COMPETITIVELY to active repressor protein’
8.  do we repeat experiments to improve accuracy or reliability?

Thanks in advance 

When you ask a whole heap of questions like this, you really should make an effort to show where your thinking is at on them. Not only does that help you learn biology, it also helps the person answering the question address where you're struggling a bit better

1. Not a term you'll ever use in Biology, but no they're not really
2. They are part of the exons, yes. If they were part of the introns, they'd be removed and then translation couldn't start nor, if it did start, could it stop.
3. No. Don't worry about it, it's beyond VCE.
4. Nucleotides of the same species of nucleic acid (e.g. in DNA it's replaced with a DNA nucleotide)
5. No. Regulatory genes have to produce an RNA...they have to be transcribed. Operator regions are not.
6. Huge can of worms. It's super interesting, but it's also knowledge that is well beyond VCE. The short and sweet of it though is that there are certain types of RNA beyond those that you've learned about that can play a role in controlling gene expression. If you want something to Google to convince you this is the case, try "miRNA"
7. No. Don't think of lactose as an inhibitor. Inhibitors are molecules that prevent the binding of another molecule. What does lactose prevent from binding in the case of lac operon (which is what I think you're referring to)?
8. I'd like to hear your thoughts about this one. If you know what the definitions of accuracy and reliability are, this should be a straightforward question.

Is all the stuff in the atar notes bio book the only things we have to know or are there any additional stuff?

This question is best answered by looking at the study design and seeing what you have to know..

'only 1 strand contains bases coding for characteristics' is this strand the template/anti-sense/non-coding strand or the non-template/sense/coding strand?

 tia

That's the template strand

It's the coding strand...

[psychologie]

7. No. Don't think of lactose as an inhibitor. Inhibitors are molecules that prevent the binding of another molecule. What does lactose prevent from binding in the case of lac operon (which is what I think you're referring to)?

8. I'd like to hear your thoughts about this one. If you know what the definitions of accuracy and reliability are, this should be a straightforward question.

7. lactose acts as an inducer and binds to the active repressor protein (repressor) ,changing its shape and making it inactive thus PREVENTING repressor from binding to the operator region; thereby allowing RNA polymerase to  bind to the promoter region and transcription to occur. this is my understanding of it and exactly what we've been told to write at school

8. well i thought that it would improve reliability (the ability to get the same results if the experiment was replicated) because when we repeat results, we can ensure we're getting the same result every time. but in my notes it says 'we repeat experiments to decrease chances of error and improve accuracy'

[vox nihili]

7. lactose acts as an inducer and binds to the active repressor protein (repressor) ,changing its shape and making it inactive thus PREVENTING repressor from binding to the operator region; thereby allowing RNA polymerase to  bind to the promoter region and transcription to occur. this is my understanding of it and exactly what we've been told to write at school

8. well i thought that it would improve reliability (the ability to get the same results if the experiment was replicated) because when we repeat results, we can ensure we're getting the same result every time. but in my notes it says 'we repeat experiments to decrease chances of error and improve accuracy'

That's a very good description of what lactose does in the setting of the lac operon. It's still not considered an inhibitor in this case though. It's a really pedantic definition and if you didn't understand the difference it really wouldn't matter at all in VCE to be perfectly honest. I'm reluctant to go into it because it's just needlessly confusing and really makes no difference.

It's actually a trickier question than I first appreciated.
Reliability and accuracy are both inherent properties of the experiment. You don't change the accuracy of each measurement by repeating the experiment, nor do you increase the reliability (i.e. the variation in those measurements) by repeating the experiment. However, by pooling together results from repeating experiments, the final measurement you derive (the average) is more accurate than any individual measurement. So repeating doesn't improve the inherent accuracy of each result, but it does make your final result more accurate by accounting for variations in the measurement apparatus.

[ImmaculateJeff]

I think the notes are supposed to be used as a supplement to your textbooks. I think most of the info is in the notes but def look at your textbook to make sure you haven't missed out in learning anything important

But in the lecture we were told that the book has too much extra info that is not needed and the notes are basically ALL that you need to know as they exactly what you have to know???

[plsbegentle]

But in the lecture we were told that the book has too much extra info that is not needed and the notes are basically ALL that you need to know as they exactly what you have to know???

They are trying to sell a product here,they will obviously try to convince you to buy their stuff, there's no way in hell you can just rely on the notes for the whole year. You'll be missing chunks everywhere, your right in saying that the text book gives extra unnecessary information, but is it really a bad thing to read em? Sure, you might think its a waste of time reading stuff that wont be covered on the exam, but it can also further deepen your knowledge of the thing you're learning. The notes should be used as a side thing, like if you've reading about enzymes in your text book and still think you don't understand it quite well, you can read the notes. Although i must say, the notes are pretty damn good but not good enough to dump your textbooks

[ImmaculateJeff]

They are trying to sell a product here,they will obviously try to convince you to buy their stuff, there's no way in hell you can just rely on the notes for the whole year. You'll be missing chunks everywhere, your right in saying that the text book gives extra unnecessary information, but is it really a bad thing to read em? Sure, you might think its a waste of time reading stuff that wont be covered on the exam, but it can also further deepen your knowledge of the thing you're learning. The notes should be used as a side thing, like if you've reading about enzymes in your text book and still think you don't understand it quite well, you can read the notes. Although i must say, the notes are pretty damn good but not good enough to dump your textbooks

yeeee.....but i cbs with the extra stuff, I only wanna know shit that'll be relevant to the exam, which is why I was asking

[ImmaculateJeff]

and ik theyre trynna sell their product but still....

[omgvce]

Is red light the wavelength under which plants can photosynthesise at the fastest rate? I came across the fish tank question from the 2010 VCE Biology paper and the answer was red light, but I went to search up why online and people on quora were saying it was blue light. My friend said white light was the one plants photosynethsise at the fastest rate under because acessory pigments absorb the green light...

I'm quite confused. 

[Quantum44]

Is red light the wavelength under which plants can photosynthesise at the fastest rate? I came across the fish tank question from the 2010 VCE Biology paper and the answer was red light, but I went to search up why online and people on quora were saying it was blue light. My friend said white light was the one plants photosynethsise at the fastest rate under because acessory pigments absorb the green light...

I'm quite confused. 

The absorption spectrum for plants follows a general trend of high absorption for blue (400-450nm) and red (650-700nm) light with low absorption for everything in between. Although for specific pigments it varies slightly. As far as I'm aware, blue light is absorbed more than red light so blue light would be better for photosynthesis.

https://www.khanacademy.org/science/biology/photosynthesis-in-plants/the-light-dependent-reactions-of-photosynthesis/a/light-and-photosynthetic-pigments

This article has a good explanation

Edit:

Actually it seems that while blue light is absorbed better, the energy absorbed is not as efficiently used for photosynthesis as the red light due to carotenoids.

Here is another article explaining this

https://www.researchgate.net/post/Why_the_rate_of_Photosynthesis_is_higher_in_red_light_while_the_rate_of_absorption_is_highest_of_blue_light