HSC Biology Question Thread

[kauac]

When blood pressure drops, the body responds by:
A) releasing ADH to increase reabsorption of water
B) releasing ADH to increase uptake of salts
C) releasing aldosterone to increase reabsorption of water
D) releasing aldosterone to increase uptake of salts


Why is the answer for this question A and not d

Potentially because more water = higher blood volume, and higher blood volume increases blood pressure more rapidly? In homeostasis, the body works efficiently to counteract changes, whilst I think the effect of increased salts would more gradually increase blood pressure. 

Hey guys was wondering if someone could please give me a thorough explanation to HSC 2017 MCQ9. and MC.Q20.
https://educationstandards.nsw.edu.au/wps/wcm/connect/fc23024b-f91e-468c-90b5-8d522b8d2dbf/2017-hsc-biology.pdf?MOD=AJPERES&CACHEID=ROOTWORKSPACE-fc23024b-f91e-468c-90b5-8d522b8d2dbf-m0Qr1Ki
Many thanks 

Hi...

Q9: Definitely seems a bit like a trick question! Test tube Y is the experiment because it is the only one containing both amylase and starch. Test tube W is the control because they wanted to check whether starch naturally reacted with itself. The 1ml of water ensures there is the same ratio of molecules as in Test tube Y. Thus, the Y & W option is A, so this is the answer. 

Q20: Straightaway we know it cannot be C, because enzymes are not used in the reaction. It can't be B, because the reaction is still producing the product, so product concentration cannot be decreasing. A seems logical, but it is stretched to get this conclusion from the graph. Therefore, the answer must be D. 

[jasn9776]

http://www.k6.boardofstudies.nsw.edu.au/wps/wcm/connect/88b8b597-9f96-46d5-a389-0a86145f97bb/biology-hsc-exam-2008.pdf?MOD=AJPERES&CACHEID=ROOTWORKSPACE-88b8b597-9f96-46d5-a389-0a86145f97bb-lGcvlf6

2008 Q15: i need help with this punnett square. I understand how to narrow it down to C and D since the male gets the X-chromosome from the mother but i don't know why D is wrong.

[Sine]

http://www.k6.boardofstudies.nsw.edu.au/wps/wcm/connect/88b8b597-9f96-46d5-a389-0a86145f97bb/biology-hsc-exam-2008.pdf?MOD=AJPERES&CACHEID=ROOTWORKSPACE-88b8b597-9f96-46d5-a389-0a86145f97bb-lGcvlf6

2008 Q15: i need help with this punnett square. I understand how to narrow it down to C and D since the male gets the X-chromosome from the mother but i don't know why D is wrong.

D is wrong because there is nothing called a male "carrier" they are either affected on unaffected for sex linked diseases .

[siimraan]

Can someone please explain what Sutton and Boveri did?

[blasonduo]

Can someone please explain what Sutton and Boveri did?

Hey!

Walter Sutton : Studied meiosis in grasshoppers, noted similarities between chromosomal behaviour and laws of segregation/independent assortment
- Segregation: During meiosis, each gamete cell receives one chromosome of each pair
- Independent Assortment: Chromosomes arrange themselves independently along the middle of the cell just before it divides

This meant that genes would segregate independently if they were on different homologous chromosomes and suggested that all characteristics followed Mendel’s law of independent assortment. Through this, he concluded that several Mendelian factors are present in 1 chromosome, could be inherited as a unit and that chromosomes were carriers of hereditary information.


Theodore Boveri: Experimented with sea urchins, provided evidence for the halving of chromosome numbers during the process of meiosis and that a definite set of chromosomes is required to produce normal development.
- Zygote chromosomes: 50% egg, 50% sperm

He showed that if the nucleus of only one parent was present, the larvae resembled that parent, but with some abnormalities. When a healthy egg and sperm fused, the resulting offspring showed characteristics of both parents.


Both of their works led to the Chromosomal theory of inheritance which means chromosomes carry genetic information (DNA).

I hope this helps! If you need any of this explained more, let us know!

[jasmineghanem]

hey guys

in regards to SFBH, for the gene expression & maintenance of health and repair of body tissue dotpoint, is there an easier/simpler example other than the BRCA1 gene & PTEN gene example?

thanks in advance!!

[kauac]

hey guys

in regards to SFBH, for the gene expression & maintenance of health and repair of body tissue dotpoint, is there an easier/simpler example other than the BRCA1 gene & PTEN gene example?

thanks in advance!!

Hi...
Not sure what example you are referring to, but for this dotpoint, I generally talk about the ramifications of the mutations of different genes involved with the cell cycle. Some examples:

- Mutation of p53 gene --> cell cycle does not pause to repair DNA -->  --> can lead to tumours (50% of cancer cases involve a mutation of p53).
- Mutation of DNA repair genes --> DNA damage accumulates --> production of incomplete proteins --> impaired functioning of cells.
- Mutation of tumour supressor genes or proto-oncogenes --> uncontrolled cell division --> tumour.

I have seen examples talking about the gene for cystic fibrosis (CFTR), but I think the above ones are easier to use. Hope this helps! 

[jasmineghanem]

Hi...
Not sure what example you are referring to, but for this dotpoint, I generally talk about the ramifications of the mutations of different genes involved with the cell cycle. Some examples:

- Mutation of p53 gene --> cell cycle does not pause to repair DNA -->  --> can lead to tumours (50% of cancer cases involve a mutation of p53).
- Mutation of DNA repair genes --> DNA damage accumulates --> production of incomplete proteins --> impaired functioning of cells.
- Mutation of tumour supressor genes or proto-oncogenes --> uncontrolled cell division --> tumour.

I have seen examples talking about the gene for cystic fibrosis (CFTR), but I think the above ones are easier to use. Hope this helps! 

thank you so much! they're heaps easier 

[MrBarbour]

Could someone explain the role of Antibodies?
I thought it was like a targeting system that enables white blood cells to see which cells to kill
Do antibodies kill the pathogen?

[vox nihili]

Could someone explain the role of Antibodies?
I thought it was like a targeting system that enables white blood cells to see which cells to kill
Do antibodies kill the pathogen?

This link provides a pretty straightforward answer to this http://bfy.tw/KTQD

[Mate2425]

Hey, so what do we do if we need more writing space/paper for the short response Q and not option Q?

[MrBarbour]

Hey, so what do we do if we need more writing space/paper for the short response Q and not option Q?

You ask one of the exam supervisors for another spare booklet to re-write or for more writing space for that particular question. They give you a booklet, write your student number, centre number and the question you are answering in that box which states which question you are answering.

[moq418]

What if you write below the lines of 6 lines for example and there so space can’t you just write on the black space provided ??

ALSO ANY TRENDS FOR BIOLOGY QUESTIONS PLEASE TELL ME
THANKS IN ADVANCE!

[jswimj]

Hey everyone!

Is anyone familiar with questions in HSC bio that always pop up in different years?
If so, could you please let me know, because i've been looking but i cant find them

Thanks in advanced!!

[Razeen25]

What if you write below the lines of 6 lines for example and there so space can’t you just write on the black space provided ??

I REALLY need to know this. I always overwrite my biology answers over the lines, and the thought of having to ask for a new writing booklet for every single question feels like it'll be the biggest waste of time. My legal supervisors today said you cant write in the blank space (