HSC Biology Question Thread

[Skidous]

How many pages should you be writing for 7 and 8 markers in the exam? I know in the core topic, it gives you one page usually for the 7/8 marker but usually for all of the questions you need more lines, so how many pages is the optimal number? Also for the option topic, where there is no line indication, how many pages should we write for the long responses?

For the core topics you should actually stick to the number of lines given as they give an indication to the length of the responses in an exam, a couple lines over is ok but you want to answer the question in a concise and succinct manner.

As for the option topic I would recommend 2 pages for the 7-8 markers depending on what they are asking for the question. If it is a table it should be approximately 1 page with maybe 1/2 a page for some discussion if need be.

I hope this helps

[Skidous]

Oxygen levels in blood will decrease after it passes the kidney. Your first set of notes are correct. According to my notes, carbon dioxide is the only chemical that increases after blood passes through the kidney.

Just to add onto this the only place where oxygen should increase in blood, according to my knowledge, is in the lungs where the oxygen mixes with the blood and removes CO2. Everywhere else in the body oxygen in the blood should be decreasing as cells take oxygen for respiration

[Skidous]

I guess so but I was taught WBC were 10-12 μm

Some text books have this but if you do some research using google you can find different answers, 12 μm is not incorrect but 10 may be too small, just as 15 may be too large so it would be wise to remember that WBC are at least 12μm in diameter

[melprocrastinator]

Oxygen levels in blood will decrease after it passes the kidney. Your first set of notes are correct. According to my notes, carbon dioxide is the only chemical that increases after blood passes through the kidney.

Ok, cool, thanks.

Just to add onto this the only place where oxygen should increase in blood, according to my knowledge, is in the lungs where the oxygen mixes with the blood and removes CO2. Everywhere else in the body oxygen in the blood should be decreasing as cells take oxygen for respiration

does that mean Co2 rises in the blood when it goes past the lungs??

[Skidous]

Ok, cool, thanks.

does that mean Co2 rises in the blood when it goes past the lungs??

The CO2 lowers when it goes past the lungs and increases when it passes through all other organs

[melprocrastinator]

The CO2 lowers when it goes past the lungs and increases when it passes through all other organs

ah ok, Thankyou!

[melprocrastinator]

Hey, i have another question. I know fish produce ammonia. However, im not sure if ammonia needs a loy of water to be produced?

[imtrying]

Hey:)
Are the marker molecules on the surface of transplanted organs which cause an immune response referred to as antigens or is it that they have a different MCHI molecule?

Also, one of the focus areas for the search for better health topic refer to a scientist called Macfarlane Burnet but I dont seem to have any notes on him. Is there anything specific we need to know about him?

[Blissfulmelodii]

Hey:)
Are the marker molecules on the surface of transplanted organs which cause an immune response referred to as antigens or is it that they have a different MCHI molecule?

Also, one of the focus areas for the search for better health topic refer to a scientist called Macfarlane Burnet but I dont seem to have any notes on him. Is there anything specific we need to know about him?

I'm not 100% about that first part but I can try and answer your second question. There is technically no dot point on Burnet which is probably why you don't have any notes on him, i myself only got a short paragraph intro into him when my class went through search for better health but i guess all you would really need to know about him is that he made a significant contribution to the understanding of the immune response. He investigated the reason why the immune system can respond to foreign substances without destroying its own cells in the process and concluded that immunity is gradually acquired over the course of foetal development. He did this by introducing foreign cells to foetus in utero and noted that these foreign cells were not rejected.

He also used chicken eggs to develop a way to isolate spcific viruses - allowing for creation of vaccines like the influenza vaccine 

[imtrying]

I'm not 100% about that first part but I can try and answer your second question. There is technically no dot point on Burnet which is probably why you don't have any notes on him, i myself only got a short paragraph intro into him when my class went through search for better health but i guess all you would really need to know about him is that he made a significant contribution to the understanding of the immune response. He investigated the reason why the immune system can respond to foreign substances without destroying its own cells in the process and concluded that immunity is gradually acquired over the course of foetal development. He did this by introducing foreign cells to foetus in utero and noted that these foreign cells were not rejected.

He also used chicken eggs to develop a way to isolate spcific viruses - allowing for creation of vaccines like the influenza vaccine

Thanks so much!

[Skidous]

Hey, i have another question. I know fish produce ammonia. However, im not sure if ammonia needs a loy of water to be produced?

Ammonia readily dissolves in water so as long as there is water nearby it dilutes very easily, you just have to be concerned with the concentration of the secretion based up freshwater and marine fish

[Skidous]

Hey:)
Are the marker molecules on the surface of transplanted organs which cause an immune response referred to as antigens or is it that they have a different MCHI molecule?

Also, one of the focus areas for the search for better health topic refer to a scientist called Macfarlane Burnet but I dont seem to have any notes on him. Is there anything specific we need to know about him?

Marker molecules are actually protein flags on all of the tissues within the body. The reason why an immune response occurs is due to the fact that invading foreign bodies (not necessarily pathogens) have different sets of these flags (different types, too many, too little or none at all) and that triggers an immune response as the body detects the antigen as 'Non-Self'

When an organ is transplanted that isn't similar to the patient's tissue type or when a person who has had a transplant stops taking immunosuppressants then the immune response attacks the organ.

The protein flags themselves are not antigens but the human immune system recognises them as non-self and will treat the organ as though it is an antigen.

Hope this helps

[Blissfulmelodii]

Marker molecules are actually protein flags on all of the tissues within the body. The reason why an immune response occurs is due to the fact that invading foreign bodies (not necessarily pathogens) have different sets of these flags (different types, too many, too little or none at all) and that triggers an immune response as the body detects the antigen as 'Non-Self'

When an organ is transplanted that isn't similar to the patient's tissue type or when a person who has had a transplant stops taking immunosuppressants then the immune response attacks the organ.

The protein flags themselves are not antigens but the human immune system recognises them as non-self and will treat the organ as though it is an antigen.

Hope this helps

Though i did not ask the question, that actually really helped me understand. Thank you for responding!

[imtrying]

Marker molecules are actually protein flags on all of the tissues within the body. The reason why an immune response occurs is due to the fact that invading foreign bodies (not necessarily pathogens) have different sets of these flags (different types, too many, too little or none at all) and that triggers an immune response as the body detects the antigen as 'Non-Self'

When an organ is transplanted that isn't similar to the patient's tissue type or when a person who has had a transplant stops taking immunosuppressants then the immune response attacks the organ.

The protein flags themselves are not antigens but the human immune system recognises them as non-self and will treat the organ as though it is an antigen.

Hope this helps

Thanks! That helped heaps:)

[imtrying]

Hi again:)
In the Communication topic there's a dot point that says a nerve is a bundle of neuronal fibres. Are neuronal fibres just neurones?