HSC Biology Question Thread

[Potatohater]

Hi there! This might be a silly question but I was wondering if there are any strategies or tips in answering questions along the lines of "Evaluate the reliability/validity of this experiment? How would you go about answering these questions (eg. Q 28a 2016 paper) Thank you ! 

Ok so, evaluate according to BOSTES/NESA = make a judgment based on criteria; determine the value of
Reliability is "is the experiment consistent and trustworthy?"
Validity is "is the experiment testing what I want to test?"
So in these sorts of questions I would go about it by explaining the criteria against which you are evaluating the experiment (validity/reliability) then show what makes the experiment valid/ reliable, what makes the experiment invalid/ unreliable and then give a final judgment as to the degree of validity/reliability.
For this evaluation it's good to use words such as: nearly, slightly, moderately, relitivley, somewhat, very, greatly, extremley, substantially, little, average, huge etc. there are lots of words you can use but basically they all give an extent to which the experiment is valid/ reliable
Eg. Due to XYZ, this experiment is of substantial reliability/validity
Hope this helps 

[av-angie-er]

Hi! When a question refers to the 'management' of a disease, would this include both the prevention and treatment of it? For example, would vaccination be appropriate as a method of managing a disease even though it's administered as a measure of prevention before the disease is contracted and needs to be 'managed'? Probably a silly question, but thanks in advance!

[taylorlucy]

Hi! When a question refers to the 'management' of a disease, would this include both the prevention and treatment of it? For example, would vaccination be appropriate as a method of managing a disease even though it's administered as a measure of prevention before the disease is contracted and needs to be 'managed'? Probably a silly question, but thanks in advance!

Hi! I'm no expert so my answer may not be totally correct, but I'll help how I can. First of all, are you referring to a particular question? If so, is it specifically about non-infectious disease? I have found that 'management' itself has to do with how one copes with/responds to a non-infectious disease once they have it; similarly to 'treatment', as infectious diseases aren't really 'managed' - but rather controlled and eventually (hopefully) defeated by the immune system. To talk about this further we'll want to refer to two particular parts of the syllabus:

Identify data sources, gather, process and analyse information from secondary sources to describe one named infectious disease in terms of its: cause, transmission, host response, major symptoms, treatment, prevention and control.

Identify data sources, gather information from secondary sources to analyse and present information about the occurrence, symptoms, cause and treatment/management of a named non-infectious disease

So basically one of these requires an in depth study of an infectious disease and the other requires an in depth study of a non-infectious disease. The specifics that each dot point asks for, however, are slightly different. For infectious disease you do not need to know about 'management', which to me implies that one only 'manages' a non-infectious disease. I believe this would be the case especially in terms of incurable disorders, where the focus is on alleviating the symptoms and improving a person's quality of life, rather than preventing or controlling it as you would an infectious diseases.

The infectious disease I focused on was Cystic Fibrosis: an incurable genetic disorder. Some of the examples I have under 'treatment/management' are 'antibiotics to treat lung infections', 'enzyme replacement tablets to aid food digestion' and 'salt and vitamin supplements'.

Hope this helps!

[arunasva]

Not all stimuli generate a response, if they did we'd probably go crazy! Therefore the membrane potential must reach the -55 threshold (from a resting potential of -70) to stimulate an electrochemical signal, and thus response. It's like a gun, all or nothing, either the trigger is pulled or it doesn't.

When the response is triggered the electrochemical signal is generated by making the normally negative inside, positive. This is done by opening sodium channels. The more sodium that's let in, the easier it is for more sodium to come in, and so the inside becomes positive and the out side negative. (Depolarisation)
Once the signal has been generated and sent along the neurone the negatively charged inside is restored by removing potassium ions. This causes the downward turn of the graph (repolarisation)
When graphing action potential there's also a little dip below the resting membrane potential (hyperpolerisation) which is just to create a break between signals so we aren't constantly buzzing with constant streams of infomation.
I'm hoping that cleared things up

THat's pretty dope, you're amazing, ty fam

[gillv2017]

Hi all - What are the top 10 diagrams we should know how to draw for the cores heading into the exam???

[angelahchan]

Hi, can someone please help explain why the answer for this question is C? thank you

[Sine]

Hi, can someone please help explain why the answer for this question is C? thank you
(Image removed from quote.)

Y chromosome is not in a pair of homologous chromosomes.

Recombination occurs between homologous chromosomes.

Your Puzzle journey is almost complete. You're almost done!

193455 +1185874 = Your next destination

After all your thinking, sometimes overthinking may be your hindrance

[Potatohater]

Hi, can someone please help explain why the answer for this question is C? thank you
(Image removed from quote.)

No crossing over occurs since a pair of homologous chromosomes entail one paternal and one maternal chromosome for each pair. Since females do not have a Y chromosome, there is no partner for the Y chromosome supplied by the male, and hence, crossing over cannot occur as this only happens with identical chromosomes (homologous pairs)

[av-angie-er]

Hi! I'm no expert so my answer may not be totally correct, but I'll help how I can. First of all, are you referring to a particular question? If so, is it specifically about non-infectious disease? I have found that 'management' itself has to do with how one copes with/responds to a non-infectious disease once they have it; similarly to 'treatment', as infectious diseases aren't really 'managed' - but rather controlled and eventually (hopefully) defeated by the immune system. To talk about this further we'll want to refer to two particular parts of the syllabus:

Identify data sources, gather, process and analyse information from secondary sources to describe one named infectious disease in terms of its: cause, transmission, host response, major symptoms, treatment, prevention and control.

Identify data sources, gather information from secondary sources to analyse and present information about the occurrence, symptoms, cause and treatment/management of a named non-infectious disease

So basically one of these requires an in depth study of an infectious disease and the other requires an in depth study of a non-infectious disease. The specifics that each dot point asks for, however, are slightly different. For infectious disease you do not need to know about 'management', which to me implies that one only 'manages' a non-infectious disease. I believe this would be the case especially in terms of incurable disorders, where the focus is on alleviating the symptoms and improving a person's quality of life, rather than preventing or controlling it as you would an infectious diseases.

The infectious disease I focused on was Cystic Fibrosis: an incurable genetic disorder. Some of the examples I have under 'treatment/management' are 'antibiotics to treat lung infections', 'enzyme replacement tablets to aid food digestion' and 'salt and vitamin supplements'.

Hope this helps!

Hey! Thanks so much for your answer, it was really excellent and beyond helpful As for whether or not I was addressing a question that specifically asked for an answer about non-infectious disease, the question that caught my attention was:

"Describe how TWO named methods have changed the way we manage disease and/or insect pests" (5 marks)

It doesn't specifically ask about the management of non-infectious disease, and its reference to insect pests kind of suggests that we can address infectious diseases caused by vectors. But I still totally see where you're coming from, so maybe I could address the management of non-infectious disease as one method (like the use of antibiotics for Cystic Fibrosis), and describe a method used to manage infectious disease like quarantine or immunisation programs as the other. I managed to find an exemplar answer for this question that focused on transgenic species and quarantine as methods of 'management', so I assume that these preventative measures are also considered to be valid ways of managing disease. But again, thank you so much for your help

[av-angie-er]

For the genetics elective, would anyone be able to suggest ways to approach a question asking you to compare the effects of germ line mutations and transposable gene elements? I'm having trouble thinking of some similarities and differences. Thanks!

[pikachu975]

Do antibodies work on intracellular pathogens and do cytotoxic t cells work on extracellular pathogens? Thanks

[av-angie-er]

Do antibodies work on intracellular pathogens and do cytotoxic t cells work on extracellular pathogens? Thanks

It's the other way around Plasma B cells secrete antibodies which mediate the humoral immune response, whereby the antibodies move through the blood and lymph fluid to attack extracellular microorganisms. Conversely, T cells control the cell-mediated response, which involves the activation of cytotoxic T cells, phagocytes and various cytosines that destroy intracellular pathogens. Hope this makes senses

[pikachu975]

It's the other way around Plasma B cells secrete antibodies which mediate the humoral immune response, whereby the antibodies move through the blood and lymph fluid to attack extracellular microorganisms. Conversely, T cells control the cell-mediated response, which involves the activation of cytotoxic T cells, phagocytes and various cytosines that destroy intracellular pathogens. Hope this makes senses

Oh yeah I meant like can they work on the opposite type too e.g. can cytotoxic also kill extracellular and can antibodies help with intracellular?

[arunasva]

Oh yeah I meant like can they work on the opposite type too e.g. can cytotoxic also kill extracellular and can antibodies help with intracellular?

While I do not precisely know the answer. But if Maurice Wilkins can get a Nobel Prize. Anything can happen. EVERYTHING IS POSSIBLE !

[martinarena_]

Hi!
I was just wondering, as someone just starting their HSC course, what books/textbooks would you recommend using as notes and studying for Biology?
Thank you