HSC Biology Question Thread

[Skidous]

Very sorry to keep asking questions in different posts...im finding the neuron thing a bit confusing.
Whats the go with synapses and neurotransmitters? Would i be right in saying that when the impulse reaches the synapse at the end of the axon, a neurotransmitter is released and this allows the electrical impulse to be changed to a chemical one as it crosses the synapse and then back to electrical impulse at the dendrites?

This would be corrects, however there are 2 types of this transmission

Sometimes the signal stays electrical which allows for fast communication to all other associated neurons

Other synapses are chemically based which, when an action potential occurs, causes the release of specific neurotransmitters to open ligand gates channels to promote the action potential in the next neuron and so on.

This vid could help you understand them a little better: https://m.youtube.com/watch?v=VitFvNvRIIY


Hope this helps

[Skidous]

Is it concerning that my class is also doing communication yet I am not understanding any of this?? Honestly the only thing that makes sense to me from that topic is the eye and ear stuff...

That's ok, we all have our weaknesses and strength in subjects, you just need to focus more on the stuff you do not understand or remember rather than on what you do know. If you don't understand something ask a classmate, a teacher, or even post it here, IM sure I can help

Hope to see you soon

[justdoit]

HEYY GUYS!
 
I have a few bio MC questions to ask, i dont understand why i got them wrong so here goes ...

An extremely high concentration of carbon dioxide is undesirable in active muscle tissue
because it will
(A)    increase the pH.
(B)    cause enzymes to denature.
(C)     increase cellular reaction rates.
(D)    cause haemoglobin to release oxygen.

My answer was D, which im pretty sure is right BUT the answers said B???


The    following    measures    could    be    used    to    prevent    the    spread    of    this    fruit    fly    across   
Australia.
1.    Australia-wide release of infertile fruit flies
2.    Aerial spraying of orchards throughout the country
3.    Spot spraying of newly affected orchards in Western Australia
4.    Stopping the transport of fruit from Western Australia to other states
    To prevent the spread of this fruit fly across Australia, which combination of measures
would be most practical to use?
(A)    1 and 2
(B)    1 and 4
(C)    2 and 3
(D)    3 and 4

I put B because I though of prevention, which includes the use of genetic engineering... doesnt it?  but the answers says D
If someone can help differentiate between control, prevention and treatment. That would be great

Why might epidemiology be considered more essential for the study of non‑infectious
diseases than for the study of infectious diseases?
(A) The causes of infectious diseases have already been determined.
(B) Only non‑infectious diseases are affected by patterns of behaviour.
(C) Epidemiology cannot be used to find the causes of infectious diseases.
(D) Koch’s postulates are not useful in finding the causes of non‑infectious disease

How the hell is it D
Students conducted a large first-hand investigation into enzyme activity.
The aim in the report is shown.
Aim: To determine the optimum pH of four different enzymes.
How many independent variables were in this first-hand investigation?
(A) 1
(B) 2
(C) 4
(D) 5

For an experiment to be valid shouldnt it change ONE variable at a time, then how come the answer is B

Also q. 17 from the 2015 paper, how is C not D

VERY MUCH APPRECIATE ANY HELP

[aimbotted]

HEYY GUYS!
 
I have a few bio MC questions to ask, i dont understand why i got them wrong so here goes ...

An extremely high concentration of carbon dioxide is undesirable in active muscle tissue
because it will
(A)    increase the pH.
(B)    cause enzymes to denature.
(C)     increase cellular reaction rates.
(D)    cause haemoglobin to release oxygen.

My answer was D, which im pretty sure is right BUT the answers said B???


The    following    measures    could    be    used    to    prevent    the    spread    of    this    fruit    fly    across   
Australia.
1.    Australia-wide release of infertile fruit flies
2.    Aerial spraying of orchards throughout the country
3.    Spot spraying of newly affected orchards in Western Australia
4.    Stopping the transport of fruit from Western Australia to other states
    To prevent the spread of this fruit fly across Australia, which combination of measures
would be most practical to use?
(A)    1 and 2
(B)    1 and 4
(C)    2 and 3
(D)    3 and 4

I put B because I though of prevention, which includes the use of genetic engineering... doesnt it?  but the answers says D
If someone can help differentiate between control, prevention and treatment. That would be great

Why might epidemiology be considered more essential for the study of non‑infectious
diseases than for the study of infectious diseases?
(A) The causes of infectious diseases have already been determined.
(B) Only non‑infectious diseases are affected by patterns of behaviour.
(C) Epidemiology cannot be used to find the causes of infectious diseases.
(D) Koch’s postulates are not useful in finding the causes of non‑infectious disease

How the hell is it D
Students conducted a large first-hand investigation into enzyme activity.
The aim in the report is shown.
Aim: To determine the optimum pH of four different enzymes.
How many independent variables were in this first-hand investigation?
(A) 1
(B) 2
(C) 4
(D) 5

For an experiment to be valid shouldnt it change ONE variable at a time, then how come the answer is B

Also q. 17 from the 2015 paper, how is C not D

VERY MUCH APPRECIATE ANY HELP

well for the first one, we know that an abundance of carbon dioxide in cells will lead to carbonic acid which leads to a decrease in pH = denature

the flies one its because using infertile flies takes time for flies to die, and spraying every orchid in australia is very costly and time consuming

no idea about the epidimology one

the question says determine the optimum PH of FOUR different enzymes. so you are changing the enzyme and the ph

not sure if i'm correct though

[Skidous]

HEYY GUYS!
 
I have a few bio MC questions to ask, i dont understand why i got them wrong so here goes ...

An extremely high concentration of carbon dioxide is undesirable in active muscle tissue
because it will
(A) increase the pH.
(B) cause enzymes to denature.
(C)  increase cellular reaction rates.
(D) cause haemoglobin to release oxygen.

My answer was D, which im pretty sure is right BUT the answers said B???


The following measures could be used to prevent the spread of this fruit fly across
Australia.
1. Australia-wide release of infertile fruit flies
2. Aerial spraying of orchards throughout the country
3. Spot spraying of newly affected orchards in Western Australia
4. Stopping the transport of fruit from Western Australia to other states
 To prevent the spread of this fruit fly across Australia, which combination of measures
would be most practical to use?
(A) 1 and 2
(B) 1 and 4
(C) 2 and 3
(D) 3 and 4

I put B because I though of prevention, which includes the use of genetic engineering... doesnt it?  but the answers says D
If someone can help differentiate between control, prevention and treatment. That would be great

Why might epidemiology be considered more essential for the study of non‑infectious
diseases than for the study of infectious diseases?
(A) The causes of infectious diseases have already been determined.
(B) Only non‑infectious diseases are affected by patterns of behaviour.
(C) Epidemiology cannot be used to find the causes of infectious diseases.
(D) Koch’s postulates are not useful in finding the causes of non‑infectious disease

How the hell is it D
Students conducted a large first-hand investigation into enzyme activity.
The aim in the report is shown.
Aim: To determine the optimum pH of four different enzymes.
How many independent variables were in this first-hand investigation?
(A) 1
(B) 2
(C) 4
(D) 5

For an experiment to be valid shouldnt it change ONE variable at a time, then how come the answer is B

Also q. 17 from the 2015 paper, how is C not D

VERY MUCH APPRECIATE ANY HELP

For the first question
CO2 cause an increase in acidity, decreasing the pH of the blood and the surrounding environment, which results in enzymes being out of their optimum and tolerance range causing them to denature which is why it is B. Whilst D DOES occur in the blood the reason why it does that is actually beneficial as it supplies organs with oxygen whilst sending CO2 to the lungs to be excreted.

2nd Question
The question asks for prevention of spread of the flies. 1 would not be very efficient as there would still be fertile flies to mate with whilst the infertile ones would die out.
2 is incredibly costly and ineffective
That leaves 3 and 4. 3 allows for a more cost effective way of treating infected plants whilst 4 prevents flies using fruit as a means of transport from getting into areas with unaffected orchids which is why it's D

3rd Question
Koch'a Postulates only work for infectious diseases as they rely on specific pathogens.
Non-infectious disease are cause by environmental, lifestyle and genetics that cannot be passed between people (excluding hereditary) and therefore there is no pathogen to identify, hence why D is correct

4th question
It is 2 because it says 4 DIFFERENT enzymes so 1 of them is the pH and the other is the type of enzymes

Hope this helps

[Skidous]

HEYY GUYS!
 
I have a few bio MC questions to ask, i dont understand why i got them wrong so here goes ...

An extremely high concentration of carbon dioxide is undesirable in active muscle tissue
because it will
(A) increase the pH.
(B) cause enzymes to denature.
(C)  increase cellular reaction rates.
(D) cause haemoglobin to release oxygen.

My answer was D, which im pretty sure is right BUT the answers said B???


The following measures could be used to prevent the spread of this fruit fly across
Australia.
1. Australia-wide release of infertile fruit flies
2. Aerial spraying of orchards throughout the country
3. Spot spraying of newly affected orchards in Western Australia
4. Stopping the transport of fruit from Western Australia to other states
 To prevent the spread of this fruit fly across Australia, which combination of measures
would be most practical to use?
(A) 1 and 2
(B) 1 and 4
(C) 2 and 3
(D) 3 and 4

I put B because I though of prevention, which includes the use of genetic engineering... doesnt it?  but the answers says D
If someone can help differentiate between control, prevention and treatment. That would be great

Why might epidemiology be considered more essential for the study of non‑infectious
diseases than for the study of infectious diseases?
(A) The causes of infectious diseases have already been determined.
(B) Only non‑infectious diseases are affected by patterns of behaviour.
(C) Epidemiology cannot be used to find the causes of infectious diseases.
(D) Koch’s postulates are not useful in finding the causes of non‑infectious disease

How the hell is it D
Students conducted a large first-hand investigation into enzyme activity.
The aim in the report is shown.
Aim: To determine the optimum pH of four different enzymes.
How many independent variables were in this first-hand investigation?
(A) 1
(B) 2
(C) 4
(D) 5

For an experiment to be valid shouldnt it change ONE variable at a time, then how come the answer is B

Also q. 17 from the 2015 paper, how is C not D

VERY MUCH APPRECIATE ANY HELP

As for the HSC question



The reason why it is C as the antigen is displayed on a MHC molecule, it is being Presented to the specific T-Cell (in this case a T-Helper Cell) which is providing support through cytokines to turn into plasma cells

It is not D as there is no antigen within the cell and it is not giving cytoTOXINS.
An easy mistake

Hope this helps

[justdoit]

ohhhh, thank you so much!!!!!!!!!

But still have 1 q. how does pH lead to denaturing, i thought it was only temperature...

[Skidous]

ohhhh, thank you so much!!!!!!!!!

But still have 1 q. how does pH lead to denaturing, i thought it was only temperature...

No it is not just temperature

Back when we got taught homeostasis, everything about the internally environment has an optimum and tolerance range. Water balance, salt balance, gases, temperature AND pH.

When these exceed this tolerance range the body does not perform at its optimum. These functions occur through the reactions between enzymes and substrate, if pH is not correct this can lead to the breakdown of proteins in enzymes and effectively making them dysfunctional and ineffective.

Think of it like dropping meat into a vat of acid, it would melt into nothing so if the pH is too low the enzymes would also denature

Hope this helps

[aimbotted]

ohhhh, thank you so much!!!!!!!!!

But still have 1 q. how does pH lead to denaturing, i thought it was only temperature...

disrupts the hydrogen bonds

[Skidous]

disrupts the hydrogen bonds

Just to expand on that, acids like to 'accept' hydrogens so they will rip them off of anything with with hydrogen in it such as proteins.

The answer suffices but just a little further explanation

[Skidous]

Just in case any of you were unaware (like me) or missed out. UTS held a love event where HSC questions were asked.

70 questions were answered, if you would like to take a look the link is here

https://docs.google.com/document/d/1HoR4MRbEpI-cYOfF3Hygs_kd69kjJrhs7MzsLVxevfg/preview

[melprocrastinator]

Thanks for answering my previous question. Im wondering now, if Mendel's "factors" reffered to the 'gene' or the 'allele'. Different websites seem to be saying different things...

[Skidous]

Thanks for answering my previous question. Im wondering now, if Mendel's "factors" reffered to the 'gene' or the 'allele'. Different websites seem to be saying different things...

Mendels 'Factors' are referring to genes on chromosomes. What he was test is the dominant and recessive alleles of those genes which is how we get those Mendelian ratios

[hannah11111]

Hi guys, just having a bit of trouble understanding the difference between hybridisation and transgenic species?
I know its really simple but I just don't understand haha, cause I keep getting multiple choice questions wrong for it

Thanks

[Skidous]

Hi guys, just having a bit of trouble understanding the difference between hybridisation and transgenic species?
I know its really simple but I just don't understand haha, cause I keep getting multiple choice questions wrong for it

Thanks

Hybridisation is the breeding between different species to produce a new species (like Ligers or Mules) which are usually infertile and bred for their favourable characteristics

Transgenic Species are Species which have been genetically modified to have favourable characteristics (Bt Cotton) and these are also usually infertile.

Hope this helps