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November 12, 2019, 11:50:13 pm

Author Topic: VCE Biology Question Thread  (Read 1426247 times)  Share 

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pugs

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Re: VCE Biology Question Thread
« Reply #12120 on: October 23, 2019, 05:59:50 pm »
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i also had 2 queries regarding the 2019 NEAP trial exam (questions attached)

for question 4, part c states that: "Equal is an artificial sweetener that is structurally different to glucose and is sometimes taken as a dietary supplement", and asks: "use data from the graph to confirm that Equal could be used as a dietary supplement."

the answer states that because Equal has a lower rate of respiration than glucose with the same amount of substrate, that means Equal can be used as a dietary supplement. would someone be able to explain to me please? i don't know how Equal having a lower respiration rate means it can be used as a dietary supplement :/

additionally, for the second attachment (the cladogram), when we are asked to "describe an event that may have occurred at point X that would explain the divergence of the two lineages displayed", how do you know that the even that occurred would be allopatric speciation (answer). would it be possible for either the bottleneck effect or founder's effect to have occurred instead?

thank you!


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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #12121 on: October 23, 2019, 06:16:18 pm »
+4
i also had 2 queries regarding the 2019 NEAP trial exam (questions attached)

for question 4, part c states that: "Equal is an artificial sweetener that is structurally different to glucose and is sometimes taken as a dietary supplement", and asks: "use data from the graph to confirm that Equal could be used as a dietary supplement."

the answer states that because Equal has a lower rate of respiration than glucose with the same amount of substrate, that means Equal can be used as a dietary supplement. would someone be able to explain to me please? i don't know how Equal having a lower respiration rate means it can be used as a dietary supplement :/
I think what they're getting at is that less energy is produced therefore less calories/weight gain. Don't worry about it. You won't get asked that on a VCAA exam.

additionally, for the second attachment (the cladogram), when we are asked to "describe an event that may have occurred at point X that would explain the divergence of the two lineages displayed", how do you know that the even that occurred would be allopatric speciation (answer). would it be possible for either the bottleneck effect or founder's effect to have occurred instead?

thank you!
A bottleneck wouldn't cause speciation into two different species. Founders effect could, but populations become geographically isolated during that, so that would be allopatric speciation anyway.
Basically, it's allopatric speciation because that's all you're taught about and therefore the only answer they could expect without more context.
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IThinkIFailed

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Re: VCE Biology Question Thread
« Reply #12122 on: October 23, 2019, 11:00:24 pm »
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Hey, would VCAA expect us to talk about T memory cells in a vaccine response?
E.g,
APC recognises vacccine antigens as foreign, engulfing them and presenting them on their MHC 2 markers, travelling to a lymph node and presenting it to a specific T-helper cell, activating it to differentiate and secrete cytokines to activate a specific B- cell and Tc cell to undergo clonal expansion, producing both B and T memory cells along with antibodies. Upon reinfection to the antigen, the circulating B and T memory cells rapidly encounter the antigen and differentiate quickly into B-plasma, Tc and memory cells, producing a larger volume of antibodies against the antigen, launching a greater and faster response.
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Yacoubb

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Re: VCE Biology Question Thread
« Reply #12123 on: October 24, 2019, 07:38:41 am »
+2
Hey, would VCAA expect us to talk about T memory cells in a vaccine response?
E.g,
APC recognises vacccine antigens as foreign, engulfing them and presenting them on their MHC 2 markers, travelling to a lymph node and presenting it to a specific T-helper cell, activating it to differentiate and secrete cytokines to activate a specific B- cell and Tc cell to undergo clonal expansion, producing both B and T memory cells along with antibodies. Upon reinfection to the antigen, the circulating B and T memory cells rapidly encounter the antigen and differentiate quickly into B-plasma, Tc and memory cells, producing a larger volume of antibodies against the antigen, launching a greater and faster response.

Generally vaccination questions tend to focus on antibody production because in reality many vaccines are good at inducing humoral immune responses, so you can focus on helper T cells becoming activated by APCs and releasing cytokines that drive B-cell expansion.
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Re: VCE Biology Question Thread
« Reply #12124 on: October 24, 2019, 01:29:46 pm »
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Hi, why are responses produced by steroid hormoned considered to be longer-lasting? I thought it was because the hormone-receptor complex binds directly to DNA, but protein hormones would also ultimately cause a change in gene expression?

Evolio

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Re: VCE Biology Question Thread
« Reply #12125 on: October 24, 2019, 04:40:28 pm »
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Quote
All you're testing is that "the optimal temperature would be expected to be much lower than that shown by catalase from humans." There's no need to test 37 specifically (although it would probably be easier if you were actually doing this experiment).
You'd have to also have some at 30 and 40 degrees, because you'd probably have more activity at 20 degrees than 10 (if it hadn't denatured by then) so just having those two won't show that the optimum temperature is lower.
Oh, I did say that in my answer. I said that one beaker would be exposed to 10 degrees, another one exposed to 20 degrees, another one exposed to 30 degrees and another one exposed to 40 degrees. Then, I said that a graph would be constructed to see which temp had higher catalase activity. So, just to confirm, would this be marked correct?
By the way,  measuring the 37 degrees specifically was VCAA's answer.
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Erutepa

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Re: VCE Biology Question Thread
« Reply #12126 on: October 24, 2019, 07:29:08 pm »
+1
Hi, why are responses produced by steroid hormoned considered to be longer-lasting? I thought it was because the hormone-receptor complex binds directly to DNA, but protein hormones would also ultimately cause a change in gene expression?
hydrophilic messages could potentially cause changes in gene transcription, but not necessarily. Hydrophilic signalling molecules may bind to a receptor and cause an immediate change not involving gene expression (i.e. hydrophilic signalling molecules which bind, causing a conformation change which opens ion channels). Hydrophilic signalling molecules are typically associated with faster-acting and immediate cellular responses, although there will, of course, be exceptions.
Hydrophobic signalling molecules, as you have stated do typically bind to their receptor, with the resulting complex acting as a transcription factor, and are typically longer-lasting responses
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IThinkIFailed

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Re: VCE Biology Question Thread
« Reply #12127 on: October 24, 2019, 07:41:47 pm »
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Hi, why are responses produced by steroid hormoned considered to be longer-lasting? I thought it was because the hormone-receptor complex binds directly to DNA, but protein hormones would also ultimately cause a change in gene expression?
Now, this is what my teacher told me. She said that steroid hormones are considered longer lasting because as you say, they activate genes and enable them to be expressed. My teacher says that the mRNA produced can be reused by the cell, so the response is effectively longer lasting.
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pugs

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Re: VCE Biology Question Thread
« Reply #12128 on: October 24, 2019, 10:23:54 pm »
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I think what they're getting at is that less energy is produced therefore less calories/weight gain. Don't worry about it. You won't get asked that on a VCAA exam.
A bottleneck wouldn't cause speciation into two different species. Founders effect could, but populations become geographically isolated during that, so that would be allopatric speciation anyway.
Basically, it's allopatric speciation because that's all you're taught about and therefore the only answer they could expect without more context.

ook thank you v much!!


2019 vce journal here

IThinkIFailed

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Re: VCE Biology Question Thread
« Reply #12129 on: October 25, 2019, 11:01:28 am »
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What happens if we write outside of the lines that they give us, or we write two lines in the space that one line gives us?
Will I lose marks if I do?
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Sine

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Re: VCE Biology Question Thread
« Reply #12130 on: October 25, 2019, 11:37:48 am »
+1
What happens if we write outside of the lines that they give us, or we write two lines in the space that one line gives us?
Will I lose marks if I do?

Just make sure you write inside the larger box on each page. If you don't it won't get scanned.

Evolio

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Re: VCE Biology Question Thread
« Reply #12131 on: October 25, 2019, 05:29:22 pm »
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Hi guys!
I had a question that i wanted to ask.

From the 2008 VCAA Exam 1 question 1 ii, for the part when they wanted us to explain how it being a protein facilitates its role,
I wrote: Proteins have hydrophilic core which allows hydrophilic molecules to pass through cell membrane and it has a hydrophobic outside which allowed is to settle well with the hydrophobic tails. Would this be a valid response?

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Sine

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Re: VCE Biology Question Thread
« Reply #12132 on: October 25, 2019, 05:54:39 pm »
+2
Hi guys!
I had a question that i wanted to ask.

From the 2008 VCAA Exam 1 question 1 ii, for the part when they wanted us to explain how it being a protein facilitates its role,
I wrote: Proteins have hydrophilic core which allows hydrophilic molecules to pass through cell membrane and it has a hydrophobic outside which allowed is to settle well with the hydrophobic tails. Would this be a valid response?


Yeah, it's not on the assessment report but I think it is an adequate response. Just remember not all the possible solutions for a question are included on the assessor's reports.

To improve your answer maybe be more clear you are talking specifically about structure B not just any type of protein.

Evolio

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Re: VCE Biology Question Thread
« Reply #12133 on: October 25, 2019, 08:09:33 pm »
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Yeah, it's not on the assessment report but I think it is an adequate response. Just remember not all the possible solutions for a question are included on the assessor's reports.

To improve your answer maybe be more clear you are talking specifically about structure B not just any type of protein.
Oh ok.
Thank you for the help!
 :)
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Evolio

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Re: VCE Biology Question Thread
« Reply #12134 on: October 25, 2019, 08:38:29 pm »
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Hey guys!
I have more questions to ask.

In immunity, I know that when the body is exposed to the pathogen the second time, B memory cells differentiate. So, my question is do they differentiate into B memory cells and antibody-producing B plasma cells?

Also, with regards to using DNA sequencing to see if two species are different or not. So, if they are the same species, does that mean that their DNA sequence is identical or that there are differences, but not many?

Also, from question 2 c 2016 exam, for the dependent variable I said amount of glucose left because if the enzyme is inhibited, rate of fermentation decreases which may mean that the glucose is broken down more slowly. Is this valid?

From the 2016 exam question 8 a, 4 marks
I wrote:
Variation exists in the population of sea stars. The water temperature acted as a selection pressure in the warm water environment and the cold water environment. Sea stars that gave rise to C.pentagona had a selective advantage in warmer water, for example, meaning that they were more likely to survive in the warmer water, meaning that the were able to pass on the allele that provided the ability to survive in warmer environment to their offspring and so over generations, that allele frequency increased.
I was wondering how many marks this would get and how I could improve?


Thank you for all the help everyone has given me so far! It helps so much and I really appreciate it!
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