HSC Biology Question Thread

[BrittyG]

is it possible to learn the whole syllabus in 2 weeks and get a good mark and how??

Naomi's Syllabus notes + any other bio notes from the notes downloads section, highlight, sticky notes and annotate them to actively learn then complete past paper questions.

That is my best advice for you, my friend.

[amelia20181]

what are the parts of the ear involved in
a) transmission of sound waves
b) amplification of sound waves
c) Reception of sound waves

[BrittyG]

what are the parts of the ear involved in
a) transmission of sound waves
b) amplification of sound waves
c) Reception of sound waves

Haven't quite got up to this part of the syllabus yet but hopefully, this can help
(this can be found in communications notes in the downloads section)

[amelia20181]

do helper T cels help killer T cells identify the antibody

[Opengangs]

do helper T cels help killer T cells identify the antibody

Hey, amelia20181.

The primary role of helper T cells is to activate B cells to secrete antibodies. But they also play a huge role in activating cytotoxic T cells and macrophages to attack targeted cells. It's important to note that helper T cells don't actually kill the cells; that's what cytotoxic T cells are for (:

[Scooby]

do helper T cels help killer T cells identify the antibody

Cytotoxic (killer) T cells recognise and bind MHC-bound peptide, not antibody

[amelia20181]

what does a renal dialysis machine actually do?

[martinarena_]

what does a renal dialysis machine actually do?

Hey there,
Check out the info from these links on renal dialysis, found they were really helpful and explained it really well
https://www.sjog.org.au/our-services/medical-and-surgical/renal-dialysis
https://www.youtube.com/watch?v=i0fgukbjnQw

[siimraan]

Can someone please explain this dot point,
analyse information from secondary sources to outline the evidence that led to Beadle and Tatum’s ‘one gene – one protein’ hypothesis and to explain why this was altered to the ‘one gene – one polypeptide’ hypothesis

[Razeen25]

Can someone please explain this dot point,
analyse information from secondary sources to outline the evidence that led to Beadle and Tatum’s ‘one gene – one protein’ hypothesis and to explain why this was altered to the ‘one gene – one polypeptide’ hypothesis

For this dot point, its good to know that in the early 20th century, biologists were unsure about the chemical nature of hereditary material - whether it was proteins or DNA.

George Beadle and Edward Tatum hypothesised that one GENE produced one enzyme (pretty much that DNA/genes were indeed hereditary material).
To prove their hypothesis, they conducted an experiment using a bread mould called Neurospora crassa.

- They grew the Neurospora crassa mould on a minimal medium (sugars, salts and vitamins) in test tubes.
- The spores of the mould were then exposed to x-ray radiation which INDUCED mutations (changed sequence of DNA).
- They then found that some mutant strains of the mould could not produce an amino acid essential for its survival, and could not grow.

So from this; they hypothesised that the x-ray mutated the gene that coded for the particular enzyme which was responsible for producing the amino acid (that was no longer produced). Hence, showing that ONE GENE was responsible for the production of ONE ENZYME.

Their hypothesis was altered to 'one gene - one polypeptide' because it was found that genes code for some proteins that dont become enzymes, and proteins are made up of one or more polypeptides.

So now we know that ONE GENE codes for ONE ENZYME.

I hope I just made sense then lol smh

[amelia20181]

what are the difficulties and risks associated with transfusions (of whole blood and blood products)


for b can you say
ensure the temperature is kept constant throughout the experiment

[BrittyG]

for b can you say
ensure the temperature is kept constant throughout the experiment

If you have a look at the temperature column in all experiments it remains constant at 37ºC, and the question asks to identify changes in the experiment to make it more valid. For b) you could say that having the students complete the experiment for the same amount if time would make it more valid

[amelia20181]

if there is a decrease in blood pressure would you need aldosterone to increase salt reabsorption or antidiuretic hormone

around how much should you write for a 7 marker

if you just write pelvis and not renal pelvis when labelling a diagram of a kidney would you get a mark

if the ratio of urine concentration to plasma is 4:1 would the organism be more suited to a desert environment

[KT Nyunt]

if there is a decrease in blood pressure would you need aldosterone to increase salt reabsorption or antidiuretic hormone

Aldosterone - this would increase salt concentration of blood, consequently water follows due to osmosis, increasing blood volume/pressure

around how much should you write for a 7 marker

I would say for a 7-8 mark question, you're aiming to write around two pages, depending on your handwriting and how succinctly you can communicate your ideas. But generally, aim for 2 pages at least.

if you just write pelvis and not renal pelvis when labelling a diagram of a kidney would you get a mark

I think it's definitely more accurate to say renal pelvis. But maybe if you pointed at the right spot the teacher will be kind enough to give you a mark.

if the ratio of urine concentration to plasma is 4:1 would the organism be more suited to a desert environment

So the urine concentration is much higher than plasma. That means the organism is excreting a lot of wastes and solutes but not a lot of water, as water is being reabsorbed in the plasma, giving it a low concentration. Hence, yes, the organisms is more suited to a desert environment as it is conserving water.

Hope this helps! 

[kauac]

For the syllabus dotpoint:

•   LT: explain how one of the following strategies has controlled and/or prevented disease:
-   public health programs
-   pesticides
-   genetic engineering to produce disease-resistant plants and animals

Can we still be asked about any of the 3 in an exam question??