HSC Biology Marathon 2015 (1 Viewer)

[BlueGas]

I thought cohesive = attach to walls, adhesive = attach to each other?

My bad, I gotta get some sleep, my brain can't function anymore.

 

[Fiction]

My bad, I gotta get some sleep, my brain can't function anymore.

No-no you're right haha
Google proved me wrong

 

[BlueGas]

No-no you're right haha
Google proved me wrong

"Never trust anything on the internet" - Abraham Lincoln

Question: Explain some of the chemical changes that occur in the environment with one named example.

 

[DepressedPenguino]

No-no you're right haha
Google proved me wrong

Cohesion refers to attraction of water molecules and adhesion refers to water molecules attracting to the lignin walls that makes up the xylem tubes.

 

[DepressedPenguino]

The main one I learnt, personally wasn't haemogloblin but perflurochemicals

Artificial blood can be advantageous over real blood as there is a shortage of real blood, a need for real blood to be cross-matched as certain blood types reject blood from other blood types due to the antigen contained within red blood cells, a need for there to be an absence of infectious agents and lastly as artificial blood often have a longer shelf life than real blood (e.g Perflurochemicals last for 12 months compare to real blood which has a shelf-life of around 3 months).

An example of artificial blood is Perflurochemicals. It is completely sterile and disease-free as it does not contain any biological materials, it has a longer shelf life than real blood of approximately 8 more months, it can be stored at room temperature hence making it suitable to be transported conveniently in emergency vehicles such as ambulances, furthermore perflurochemicals can be used universally with all blood types, is cheaper to produce compared to using real blood, is able to dissolve 5 times more oxygen than real blood. An example of Perflurochemicals is Oxycyte TM which is currently under trial.

Disadvantages associated with perflurochemicals include that it's around 70x smaller than real blood, hence allowing it to pass through places where real blood would not normally be able to travel in, it's need to be mixed with lipids to form an emulsion that can be mixed with blood and how it can only be used to replace the function of Red blood cells, essentially, as perflurochemicals are not able to act as disease-fighting instruments, such as white blood cells are, nor are they able to act as clotting agents, like platelets.

Therefore, although real blood is disadvantageous over artificial blood in it's cost-efficiency, artificial blood with current technology, is not able to fully replace all functions of real blood, and because of it's size, may affect metabolic processes in the body.

Nice man band 6 responses (imo) right there . By the way, what does it mean by artificial blood is cheaper to synthesis compared to using real blood? why is there a cost for using real blood?

 

[Fiction]

Nice man band 6 responses (imo) right there . By the way, what does it mean by artificial blood is cheaper to synthesis compared to using real blood? why is there a cost for using real blood?

haha thanks )

The textbook(s) I'm using - where I get my notes and such from, don't specifically mention this, however they do state that apparently getting blood cross-matched and tested for infectious diseases and such is resource heavy. So I'm assuming the cost of production of artificial blood is lower than getting real blood sorted, tested and/or separated into their various components etc.

 

[duhdevitt]

Hey guys just a quick question, how do you guys study for bio cos I put shit loads of effort and I'm only get around the 70's. If it matters, I go to a rank 40ish school

 

[Fiction]

"Never trust anything on the internet" - Abraham Lincoln

Question: Explain some of the chemical changes that occur in the environment with one named example.

Chemical changes in the environment can occur as a result of changes in salinity levels, pH or the introduction of a new chemical to the environment. These changes then act as a selection pressures upon an individual organism or species, eventually resulting in a change in the species's population as better adapted individuals survive longer than those who are not as well adapted to these selective pressures.

An example of the latter is mosquitos and DDT. When DDT was first introduced as an insectcide to kill mosquitos, a large population of individual mosquitos within the allocated region, died as a result. Therefore low concentrations of DDT was effective. However, as time passed, those individuals who were initially well-adapted to the chemicals were able to survive the initial spraying, reproduce and potentially pass on their more advantageous genetic information to their offsprings. Those who were not resistant, and hence died out, were not able to pass on their disadvantageous genes to their offspring. This meant that the population of mosquitos resistent to DDT grew in size therefore subsequent sprayings of DDT needed much higher concentrations than the initial spraying. That is, DDT had become less effective.

Hence the gene pool of mosquitos had changed due to a change in the chemical environment, that is the introduction of DDT as an insecticide where DDT acted as a selection pressure.

 

[Fiction]

Hey guys just a quick question, how do you guys study for bio cos I put shit loads of effort and I'm only get around the 70's. If it matters, I go to a rank 40ish school

That's me, but with a different school rank lol

For some reason, I keep bombing out during actual tests.

 

[BlueGas]

Hey guys just a quick question, how do you guys study for bio cos I put shit loads of effort and I'm only get around the 70's. If it matters, I go to a rank 40ish school

By effort, what do you mean? Memorising? Understanding? If I have an upcoming test, I'd just memorise the whole module, but not all in one go, I'll memorise a chapter fully until I move onto the next one. Once you're done with a chapter, ask maybe your brother or sister to ask you questions.

You should memorise the chapter fully to a point that if your brother/sister is looking at a page in the chapter, you'll know what he/she is looking at and you'll answer him/her before he/she even asks the question. I'm saying this because when my brother asks me questions, he goes in order from the first page to the last, and I'll already know what he's going to be asking me and it helps me memorise better. This is just how I study, hopefully you find a way of studying which is better for you and will make your marks skyrocket.

 

[DepressedPenguino]

haha thanks )

The textbook(s) I'm using - where I get my notes and such from, don't specifically mention this, however they do state that apparently getting blood cross-matched and tested for infectious diseases and such is resource heavy. So I'm assuming the cost of production of artificial blood is lower than getting real blood sorted, tested and/or separated into their various components etc.

Yeah same with the notes that i found.. only mentions that artifical blood cost more than using donated blood but doesn't provide any further justification. However, after reading your reasoning, i think you could be right with the high cost of dobated coming from getting it sorted into its blood types and testing it to see if it carries any pathogens. Thanks again

 

[Fiction]

Yeah same with the notes that i found.. only mentions that artifical blood cost more than using donated blood but doesn't provide any further justification. However, after reading your reasoning, i think you could be right with the high cost of dobated coming from getting it sorted into its blood types and testing it to see if it carries any pathogens. Thanks again

Nw

Evaluate the following statement:
Evolution is both supported and not supported by paleontological evidence. (5 marks)

 

[astab]

Why do freshwater fish actively absorb salts if they gain a lot of water by osmosis? Wouldn't salt absorption attract even more water, causing it to burst?

 

[astab]

Hey guys just a quick question, how do you guys study for bio cos I put shit loads of effort and I'm only get around the 70's. If it matters, I go to a rank 40ish school

Videos are also really good to work with (look on Youtube). If the theory is visually presented, you'll more likely understand and remember it.

 

[BlueGas]

Nw

Evaluate the following statement:
Evolution is both supported and not supported by paleontological evidence. (5 marks)

The theory of evolution is supported by Paleontology, which is the study of fossils. A fossil record shows the sequence of the earliest of life to today's present organisms, this supports the theory of evolution and suggests that there is evidence of change in organisms. An example is horses:

- Early horses were small animals, with four toes and a small check span.
- Modern horses are large horses, with one toe and a large check span.

The fossil record of horses shows that horses evolved from being small, having more than one toe and a small check span to horses that are large, have one toe and a large check span.


I don't know the answer to why evolution is not supported by paleontological evidence, I haven't come across such a question before.

 

[DepressedPenguino]

Can someone confirm whether phagocytosis occurs in the lymph nodes?

From what i have read so far, only B and T lymphocytes are located in the lymph nodes and not phagocytes (which can perform phagocytosis).

 

[duhdevitt]

Can someone confirm whether phagocytosis occurs in the lymph nodes?

From what i have read so far, only B and T lymphocytes are located in the lymph nodes and not phagocytes (which can perform phagocytosis).

Well from my notes:
Lymph nodes store lymphocytes and macrophages. Macrophages are developed from monocytes which are a type of phagocytes. So I'm pretty sure phagocytosis occurs in lymph nodes as they store phagocytes. I'm not 100% sure, can someone clarify this


atar goal:91 but will be happy with 85+

 

[DepressedPenguino]

Never mind i got it now

 

[duhdevitt]

Never mind i got it now

What's the answer cos I'm not sure aswell lol


atar goal:91 but will be happy with 85+

 

[DepressedPenguino]

Well from my notes:
Lymph nodes store lymphocytes and macrophages. Macrophages are developed from monocytes which are a type of phagocytes. So I'm pretty sure phagocytosis occurs in lymph nodes as they store phagocytes. I'm not 100% sure, can someone clarify this


atar goal:91 but will be happy with 85+

Yeah i just found that macrophages do exist in the lymph nodes too !