HSC Biology Question Thread

[angelahchan]

Hey this is the method i have for how to produce a transgenic species and i just wanted to make sure it was correct or if it had too much/too little detail? Thanks!
1. Identify desired gene
2.Isolate genes using restriction enzymes that cuts out sections of DNA from both organisms (often bacteria) so sticky ends of DNA match, creating recombinant DNA when inserted into the genome of the second organism (the plasmid of the bacteria)
3. Make multiple copies of the gene
4. Insert gene into the organism/culture and infect a tissue with it.

Yeah that's pretty much it in terms of detail. Just remember it's the enzyme ligase which helps the gene stick to the bacteria plasmid. Also make sure you know a few ways the gene is inserted into the genome (i.e. micro-injection of DNA, gene gun, and using a virus) but I see you have briefly mentioned it

can someone help me with this question?
It's from 2015 HSC paper - q15

I thought the answer was A, but apparently it's C.

Someone please explain...

The trick is the question writing "F2 generation" (idk how to put this in bold), meaning the flowers have been crossed twice. So RR x YY = RY, RY, RY, RY
And then the next cross is RY * RY = RR, RY, RY, YY which satisfies the ration of approx. 1:2:1 red:orange:yellow
Thus the answer is C (RR x YY)

[ca052267]

Thank you soo much!

I was really confused, but it makes so much sense now...

[bridie_2345]

hi there was just wondering what the difference was between cell differentiation and cell specialisation?

[kemi]

hi there was just wondering what the difference was between cell differentiation and cell specialisation?

Hello

From what I understand, cell differentiation is the process by which cells become specialised. That is, stem cells differentiate to become muscle cells, skin cells, blood cells, etc and their specialisation is the function they carry out i.e. red blood cells carry oxygen. Though it is more complex, differentiation is like the 'structural' differences and 'specialisation' refers to the switching on of specific genes, so that the cell carries out specific functions. That's all I'd suggest you know for HSC

[adelaidecruz]

Hi! Does anyone know if we need to know anything about complement proteins and neutrophils in the 2nd line of defence (or just macrophages)? Thanks!

[bridie_2345]

Hi! Does anyone know if we need to know anything about complement proteins and neutrophils in the 2nd line of defence (or just macrophages)? Thanks!

Hey there as its so complex i think we just need to know about macrophages

[Daniyahasan]

Hey there as its so complex i think we just need to know about macrophages

It's just neutrophils basophils that kinda stuff not too much in detail

[Daniyahasan]

Hi everyone -- not sure if this has been asked before but does anyone know of a good example for a transgenic animal? Info on oncomouse seems a bit limited..

Idk many animals but you could do strawberries with the antifreeze salmon gene or by cotton...

[bridie_2345]

Hello

From what I understand, cell differentiation is the process by which cells become specialised. That is, stem cells differentiate to become muscle cells, skin cells, blood cells, etc and their specialisation is the function they carry out i.e. red blood cells carry oxygen. Though it is more complex, differentiation is like the 'structural' differences and 'specialisation' refers to the switching on of specific genes, so that the cell carries out specific functions. That's all I'd suggest you know for HSC

Ahh my god that's so much clearer, thanks so much! X

[farheen_hameed1]

Hey guys, just wanted to ask if a flowchart counts as a diagram? Say the question was "Draw a diagram showing the path of soundwaves", could I just show it in a flowchart or would I have to draw a diagram of the ear?

[farheen_hameed1]

Hey guys, just wanted to know, does a flowchart count as a diagram?

[kemi]

Hey guys, just wanted to ask if a flowchart counts as a diagram? Say the question was "Draw a diagram showing the path of soundwaves", could I just show it in a flowchart or would I have to draw a diagram of the ear?

Yes, a flowchart would be fine. But ensure you include enough detail, mentioning the specific part of the ear, indicating the beginning of the outer, middle and inner ear. Depending on the amount of marks you may have to mention energy transformations, but "path of sound" sounds like it requires a brief outline.

[kemi]

Hi! Does anyone know if we need to know anything about complement proteins and neutrophils in the 2nd line of defence (or just macrophages)? Thanks!

Complement sounds like s stretch and is more relevant in the 3rd line of defence, with the action of antibodies. Neutrophils are a type of phagocyte, like macrophages, except macrophages act for a longer period. Macrophages are also antigen presenting cells, whereas neutrophils are not. Neutrophils are the first cells that act in the inflammatory response, ingesting bacteria or fungi and breaking them down with enzymes, but in the later stages of infection, macrophages become dominant. Just know that neutrophils are first on site and act in the short-term to eliminate pathogens.

[angelahchan]

Hi, could someone please help explain why the answer is D?  I just don't know how we're meant to use our prior knowledge to work it out - because aren't dissolved nutrients carried in the phloem? (I don't think the phloem would be on the outer layer of the bark, idk tho)

[kemi]

Hi, could someone please help explain why the answer is D?  I just don't know how we're meant to use our prior knowledge to work it out - because aren't dissolved nutrients carried in the phloem? (I don't think the phloem would be on the outer layer of the bark, idk tho)
(Image removed from quote.)

Remember the phloem is usually located on the outermost part of the vascular bundle, so I'm assuming as ringbarking continues it will eventually disrupt the flow of nutrients through the phloem. We know it must be the phloem because the roots have died, and nutrient sap in the phloem travels all over the plant whereas water in the xylem travels from the roots to the leaves.