HSC Biology Question Thread

[Potatohater]

Ahhh yes I remeber that one now - yeah I agree the marking criteria was really simple. For mine I showed that the phloem had companion cells and sieve plates where as the xylem has thick lignin walls

[jasn9776]

Hi i just wondering if they are any alternatives to the HSC Biology 2017 Q27a answer. The answer seems too simple.
Thanks 

I would say just remember it is lignified (thus the wall on the marking criteria looks bigger) and that phloem is actually a lot smaller than xylem. It isn't obvious but xylem is actually bigger than phloem.


Question 27

In better responses, students were able to:

draw a scientific diagram of transverse sections of both xylem tissue and phloem tissue
demonstrate a distinguishing feature of xylem tissue and phloem tissue

so basically 1 mark for diagram. and 1 mark for 1 distinguishing feature. easy!.

[Mate2425]

I would say just remember it is lignified (thus the wall on the marking criteria looks bigger) and that phloem is actually a lot smaller than xylem. It isn't obvious but xylem is actually bigger than phloem.
(Image removed from quote.)

Question 27

In better responses, students were able to:


draw a scientific diagram of transverse sections of both xylem tissue and phloem tissue
demonstrate a distinguishing feature of xylem tissue and phloem tissue

so basically 1 mark for diagram. and 1 mark for 1 distinguishing feature. easy!.

Thanks Mate

[Mate2425]

Ahhh yes I remeber that one now - yeah I agree the marking criteria was really simple. For mine I showed that the phloem had companion cells and sieve plates where as the xylem has thick lignin walls

Cheers 

[edumax]

Help, please and thank you!!

[PhoenixxFire]

So it's meiosis - So there will be 4 daughter cells. It's saying that the sections above the squiggly line will swap - so you just need to write over it with what the new letters (alleles) will be.
You'll have
ABG

ABabG

abABg

abg

[Razeen25]

Y'all my Search For Better Health exam is tomorrow and I'm confused . I was doing a past paper and it says the answer is 'B', but i thought bacteria were procaryotes (which don't have membrane-bound organelles) smh.

Please help

[itssona]

http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2011exams/pdf_doc/2011-hsc-exam-biology.pdf

hi how is the answer D? Thanks

[TheBigC]

http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2011exams/pdf_doc/2011-hsc-exam-biology.pdf

hi how is the answer D? Thanks

I am a VCE kid, but I am sure I can aid you with this.
My assumption is that you are perplexed over Q17 (the other questions with an answer 'D' look fairly straight-forward - correct me if I am wrong).

Now, we already know that the parents express the same phenotype, which implies that they have the have the same alleles for the gene concerned, immediately eliminating A and B.

Through examination of the offspring produced, we can clearly observe that three phenotypes result, which eliminates C, as only two possible phenotypes are displayed (BB = dominant phenotype, Bb = dominant phenotype, bb = recessive phenotype).

Thus, the answer is D (AA = Phenotype A, AB = codominant phenotype and BB = Phenotype B).

[itssona]

I am a VCE kid, but I am sure I can aid you with this.
My assumption is that you are perplexed over Q17 (the other questions with an answer 'D' look fairly straight-forward - correct me if I am wrong).

Now, we already know that the parents express the same phenotype, which implies that they have the have the same alleles for the gene concerned, immediately eliminating A and B.

Through examination of the offspring produced, we can clearly observe that three phenotypes result, which eliminates C, as only two possible phenotypes are displayed (BB = dominant phenotype, Bb = dominant phenotype, bb = recessive phenotype).

Thus, the answer is D (AA = Phenotype A, AB = codominant phenotype and BB = Phenotype B).

OMG THANK YOU1!
(also LOL thanks for understanding the question I was stuck on XD ur a lifesaver)

[Razeen25]

Hii!
Today in my The Search For Better Health exam there was a multiple choice question showing a picture of Pasteur's experiment being modelled, and there were 2 answers (the other 2 were silly answers) I'm confused about.
The diagram showed two flasks containing broth (one broken, one unbroken) being boiled and the question was 'How is this experiment valid' or something and the two answers were:
c) The use of a control
d) The heat used to boil the broth

I chose C but I don't know if I should have chosen D smh since IDEK if there was a control rip

[PhoenixxFire]

I would say it was C because validity means that you were testing what you were supposed to be testing, which is the purpose of a control.

(I don’t know anything about that particular experiment and I did vce though)

[Ironiic]

Hii!
Today in my The Search For Better Health exam there was a multiple choice question showing a picture of Pasteur's experiment being modelled, and there were 2 answers (the other 2 were silly answers) I'm confused about.
The diagram showed two flasks containing broth (one broken, one unbroken) being boiled and the question was 'How is this experiment valid' or something and the two answers were:
c) The use of a control
d) The heat used to boil the broth

I chose C but I don't know if I should have chosen D smh since IDEK if there was a control rip

Hey, like Phoenixx said, validity is when the independent variable (the variable changed) is the only changing variable in the experiment and all other factors are controlled, hence the experiment is measuring what it's supposed to.

From what I can get from the answers, d sounds to me like a controlled variable itself but I'm not too sure; it depends on what the experiment is investigating specifically.

[PhoenixxFire]

Hey, like Phoenixx said, validity is when the independent variable (the variable changed) is the only changing variable in the experiment and all other factors are controlled, hence the experiment is measuring what it's supposed to.

From what I can get from the answers, d sounds to me like a controlled variable itself but I'm not too sure; it depends on what the experiment is investigating specifically.

I would still say that C is the correct answer. Controlling variables is more a part of reliability not validity. An experiment can be valid but not reliable.

For example if your hypothesis is ‘chickens who eat more will lay larger eggs’ but your IV is the amount of water you give them, your experiment is not valid.

To be valid your experiment just needs to be capable of testing the hypothesis. So if you use the above hypothesis but your IV is the amount of food you feed them then it is a valid experiment.

However if you then give them different amounts of water it is not a reliable experiment as the results will change each time it is repeated (because there is not a set amount of water). It is still a valid experiment though because it is still testing the effect of food on egg size.

A control also implies that all other conditions are the same.

[Ironiic]

I would still say that C is the correct answer. Controlling variables is more a part of reliability not validity. An experiment can be valid but not reliable.

For example if your hypothesis is ‘chickens who eat more will lay larger eggs’ but your IV is the amount of water you give them, your experiment is not valid.

To be valid your experiment just needs to be capable of testing the hypothesis. So if you use the above hypothesis but your IV is the amount of food you feed them then it is a valid experiment.

However if you then give them different amounts of water it is not a reliable experiment as the results will change each time it is repeated (because there is not a set amount of water). It is still a valid experiment though because it is still testing the effect of food on egg size.

A control also implies that all other conditions are the same.

Oh okay, that’s interesting. I guess your explanation makes a lot more sense; my understanding of reliability was also that when the experiment was repeated several times by a different experimenter, the same results would occur. Although I understood that validity was that the IV was the only ‘IV’ and there weren’t other factors that affected the outcome of the experiment.

Eg, if we take the experiment where beetroot slices were placed in different concentrations of pH, testing for colour of pigment leakage after a set period of time, I would say if there were varying sizes of beetroot slices in each concentration of pH, this would no longer be a controlled variable and essentially be another ‘IV’, hence the experiment would be no longer valid because the experiment is no longer testing the aim, and other variables are being investigated (if that makes sense).

I think you are definitely correct in this case, but maybe my wording was wrong, feel free to correct me.

That being said, I also agree that the answer would be C, thanks for your explanation!