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March 29, 2024, 10:30:08 pm

Author Topic: VCE Biology Question Thread  (Read 3571647 times)  Share 

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Evolio

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Re: VCE Biology Question Thread
« Reply #12120 on: October 24, 2019, 04:40:28 pm »
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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.

Erutepa

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Re: VCE Biology Question Thread
« Reply #12121 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 #12122 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 #12123 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 #12124 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 #12125 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 #12126 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?


Sine

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Re: VCE Biology Question Thread
« Reply #12127 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 #12128 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!
 :)

Evolio

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Re: VCE Biology Question Thread
« Reply #12129 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!

IThinkIFailed

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Re: VCE Biology Question Thread
« Reply #12130 on: October 25, 2019, 08:52:14 pm »
+1
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!

Yes, they differentiate into more B memory cells and also plasma cells

As for your question about DNA sequencing, correct me if I’m wrong, but there will be some differences in sequences between members of a species I’m pretty sure, as different people can have different mutations as such, so I’d say that there will still be small amounts of differences in the same species.

For question 2c from 2016,
You make a very interesting point indeed, and I’d say that glucose could be a dependent variable too. I’m not entirely sure about this unfortunately, hopefully someone smarter can provide a better input than me.

For question 8a,
You identified the selection pressures incorrectly unfortunately. If you read the question, it says that the predation is the selection pressure in the context provided, so you should identify it as such. Other than that, your natural selection framework seems fine, just identify the selection pressure properly and explain its impact.
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Erutepa

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Re: VCE Biology Question Thread
« Reply #12131 on: October 25, 2019, 09:51:55 pm »
+3
Hey guys!
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?
Members of different species do have genetic differences between them as IThinkIFailed has said. It's just that the differences between species are far more distinct than the differences among members of the species.

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?
This is a valid dependent variable (as long as you justify it), but the issue with using this as a dependent variable is that it's hard to test. When writing your experimental design you will want to include more than just the 4 points in the examiner's report, and you will probably want to specify how you are determining the amount of glucose remaining - something that is not as easy as measuring the volume of gas produced (using CO2 as a DV).
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radiant roses

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Re: VCE Biology Question Thread
« Reply #12132 on: October 26, 2019, 08:47:21 am »
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In photosynthesis, is NADPH a source of electrons AND protons (hydrogen ions) for the Calvin Cycle, or only hydrogen ions?

sarah15

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Re: VCE Biology Question Thread
« Reply #12133 on: October 26, 2019, 08:57:40 am »
+1
This question is in reference to multiple-choice question 9 from the insight 2019 biology exam. I have attached the question and answers for your reference. I do not understand why the solutions say that the Krebs Cycle does not function if the ETC does not function. Krebs occurs before the ETC, so wouldn't the ETC not function if Krebs doesn't?


Erutepa

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Re: VCE Biology Question Thread
« Reply #12134 on: October 26, 2019, 10:03:35 am »
+4
In photosynthesis, is NADPH a source of electrons AND protons (hydrogen ions) for the Calvin Cycle, or only hydrogen ions?
It is a source of both!  :)
This question is in reference to multiple-choice question 9 from the insight 2019 biology exam. I have attached the question and answers for your reference. I do not understand why the solutions say that the Krebs Cycle does not function if the ETC does not function. Krebs occurs before the ETC, so wouldn't the ETC not function if Krebs doesn't?
If the electron transport chain doesn't function, NADH isn't cycled back to NAD+. NAD+ is a neeccasary input for the Krebs Cycle, thus without the electron transport chain producing this NAD+, the Krebs Cycle will stop functioning once it has exhausted all the cells NAD+
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