HSC Biology Question Thread

[Razeen25]

Hii,

I know not many schools do the Genetics option but unfortunately my school does, and my biology teacher has been away and I'm LOST. I'm not sure if anybody here has done it but if so, could somebody please help me understand the dotpoint 'outline the procedure to produce recombinant DNA'. From what I initially understood, this was a simple process just like in Blueprint of Life as recombinant DNA refers to combining DNA from two different species, eg the process of transgenesis which I understand. But for this specific dot point, all the information in textbooks is about separating DNA, inserting it into a plasmid and then cloning it in a bacterium and I'm confused. Where does the other species' DNA come from? Or is the plasmid the other species? Genetics is really hard

[PhoenixxFire]

Hii,

I know not many schools do the Genetics option but unfortunately my school does, and my biology teacher has been away and I'm LOST. I'm not sure if anybody here has done it but if so, could somebody please help me understand the dotpoint 'outline the procedure to produce recombinant DNA'. From what I initially understood, this was a simple process just like in Blueprint of Life as recombinant DNA refers to combining DNA from two different species, eg the process of transgenesis which I understand. But for this specific dot point, all the information in textbooks is about separating DNA, inserting it into a plasmid and then cloning it in a bacterium and I'm confused. Where does the other species' DNA come from? Or is the plasmid the other species? Genetics is really hard

Obviously I don’t do HSC, so I’m not exactly sure what you need to know but we do a bit about plasmids in VCE.

So the foreign DNA is normally something that is useful to humans - for example the insulin gene.

Both it and the plasmid (from bacteria) are cut with the same restriction enzyme, leaving them with conplimentary sticky ends. They are then mixed together and some of the foreign genes will bind to the plasmid (some of the plasmids will also just rejoin without the new gene). These recombinant plasmids are then put into bacteria (plasmids are naturally exchanged between similar bacteria).

The bacteria that have the recombinant plasmid then reproduce and you end up with lots of bacteria producing insulin (or whatever the gene is for) which can then be extracted and used.

[amelia20181]

can someone please explain this

[beeangkah]

From 2015 HSC

Could someone please explain why the answer is B lol

[Razeen25]

Obviously I don’t do HSC, so I’m not exactly sure what you need to know but we do a bit about plasmids in VCE.

So the foreign DNA is normally something that is useful to humans - for example the insulin gene.

Both it and the plasmid (from bacteria) are cut with the same restriction enzyme, leaving them with conplimentary sticky ends. They are then mixed together and some of the foreign genes will bind to the plasmid (some of the plasmids will also just rejoin without the new gene). These recombinant plasmids are then put into bacteria (plasmids are naturally exchanged between similar bacteria).

The bacteria that have the recombinant plasmid then reproduce and you end up with lots of bacteria producing insulin (or whatever the gene is for) which can then be extracted and used.

Thank you this helped!

[Bri MT]

From 2015 HSC

Could someone please explain why the answer is B lol

D would suggest that strict hygiene practices shouldn't be followed for newborns, which rules it out as an answer
C isn't really relevant, so that is ruled out too
A suggests that personal hygiene is completely unnecessary for older babies - but this is untrue

We know that newborns' immune systems aren't yet mature, and that this makes them more susceptible to pathogens (hence why its an important advantage that antibodies from the mother diffuse across via the placenta before birth)


Hope this helps

[13kanel]

Heyyyyy guys

I was wondering if someone can explain T cells and B cells to me i am completely lost on them

 

[KT Nyunt]

Heyyyyy guys

I was wondering if someone can explain T cells and B cells to me i am completely lost on them

 

Here are some screenshots from my notes this gives an overview on pre much everything you need to know about B cells and T cells. Hope this helps! If you need any further clarification on anything let me know. 

[KT Nyunt]

can someone please explain this

Do you have the answers? I would probably say the answer is D.

- As substrate is being used and turned into products, the concentration of substrate will decrease (hence why it should be D)
- Enzymes can't decrease in concentration because enzymes are catalysts, hence they remain unchanged and unaffected after the reaction (so it's not C)
- The concentration of the product is technically increasing each time, it is just the rate at which the product is formed is decreasing because there's less and less substrate available (so it's not B)
- If D is not right it might be A tbh. The reason being as substrate concentration decreases, so would the rate of enzyme activity (so it's technically also right) but we have to pick the most correct answer. Since substrate concentration has a more direct correlation to the amount of product (the more product produced, the more substrate consumed), D is more correct as it explains the graph the best

Hope this helps

[amelia20181]

Thanks!

can you explain why the answer for this question is b

[Owlbird83]

Thanks!

can you explain why the answer for this question is b

Because there are two things you are changing in the experiment:
-the type of enzyme
-the pH

[amelia20181]

Are prions cells and can they reproduce outside a host cell

[ilovemycat]

hey, this is a question form 2015 hsc biology communciation section. just wondering , can someone help me out with it? im kind of confused even tho i know its supposed to be a "general/easy" question

explain why some stimuli would not generate an action potential in a neurone?

thanks so much

[kauac]

hey, this is a question form 2015 hsc biology communciation section. just wondering , can someone help me out with it? im kind of confused even tho i know its supposed to be a "general/easy" question

explain why some stimuli would not generate an action potential in a neurone?

thanks so much

Hi...

The stimuli must exceed the threshold potential in order to generate the action potential in a neurone. Any level of stimulation below the threshold will not induce anything. 

Are prions cells and can they reproduce outside a host cell

Prions are abnormal proteins, so they are a chemical, not a cell.  Therefore, they cannot reproduce as such, but rather, can cause healthy proteins in cells to assume the abnormal shape, so that they cannot function effectively. This is how they cause disease. 

[kauac]

Hi...

What is the difference between independent assortment and random segregation? I always get confused between these two...