Yacoubb's Bio 3+4 Questions

[Yacoubb]

Doubt it. Generally, if they ask a question about a specific receptor, they'll give a couple of paragraphs background first (and the questions will likely be quite straightforward or more comprehension based).

You could certainly do some light wider reading if you wanted; maybe start with the wiki pages and follow some links?

Thanks

Quick question - after attending a headstart lecture for unit 4 and being a bit exposed to its content, I've realised that my approach will differ from Unit 3. For instance, there'll be more time dedicated to actually doing monohybrid/dihybrid crossing opposed to sitting and reading notes about it. Completing questions about evolution, DNA manipulation techniques, etc. Is Unit 4 the easier unit? Unit 3 I find relatively straightforward, but unit 4 seems more appealing to me..

[alondouek]

Thanks

Quick question - after attending a headstart lecture for unit 4 and being a bit exposed to its content, I've realised that my approach will differ from Unit 3. For instance, there'll be more time dedicated to actually doing monohybrid/dihybrid crossing opposed to sitting and reading notes about it. Completing questions about evolution, DNA manipulation techniques, etc. Is Unit 4 the easier unit? Unit 3 I find relatively straightforward, but unit 4 seems more appealing to me..

I guess that's up to you, really! Some people (like myself) somewhat prefer the cell and molecular biology in the unit 3 content - but unit 4 is still brilliant, and very interesting to learn. I wouldn't say unit 4 is easier, but some people might find that to be the case; just as with unit 3, there's a lot of knowledge that you'll need to process (just wait till pedigrees haha).

[Yacoubb]

I've gone through a couple of papers and I've seen a few qs come up on describing what happens at a particular stage of aerobic cellular respiration. Could someone please check if these are sufficient

Glycolysis:
- In the cytosol of the cell, a glucose molecule is broken down into two 3-C pyruvic acid molecules.
- H⁺ ions from the glucose molecule are collected by NAD⁺ to form NADH.
- 2 ATP molecules are produced.

Krebs Citric Acid Cycle:
- At the matrix of mitochondria, the pyruvate molecules are converted to acetyl coA, where 1 CO₂ molecule is released per pyruvate molecule.
- The acetyl coA then enters the Krebs Cycle, further releasing CO₂. Altogether, 6 CO₂ molecules are released in the Krebs Cycle.
- FADH₂ and NADH are formed in Krebs Cycle.
- 2 ATP molecules are produced per glucose molecule.

Electron Transport Chain:
- Electrons in FADH₂ and NADH are carried by cytochromes through the electron transport chain.
- The energy that is released is used to drive the formation of 32-34 ATP molecules.
- The cytochromes deliver the electrons to oxygen, which then picks up two H⁺ ions to form H₂O, a by-product.

[Scooby]

I've gone through a couple of papers and I've seen a few qs come up on describing what happens at a particular stage of aerobic cellular respiration. Could someone please check if these are sufficient

Glycolysis:
- In the cytosol of the cell, a glucose molecule is broken down into two 3-C pyruvic acid molecules.
- H⁺ ions from the glucose molecule are collected by NAD⁺ to form NADH.
- 2 ATP molecules are produced.

Krebs Citric Acid Cycle:
- At the matrix of mitochondria, the pyruvate molecules are converted to acetyl coA, where 1 CO₂ molecule is released per pyruvate molecule.
- The acetyl coA then enters the Krebs Cycle, further releasing CO₂. Altogether, 6 CO₂ molecules are released in the Krebs Cycle.
- FADH₂ and NADH are formed in Krebs Cycle.
- 2 ATP molecules are produced per glucose molecule.

Electron Transport Chain:
- Electrons in FADH₂ and NADH are carried by cytochromes through the electron transport chain.
- The energy that is released is used to drive the formation of 32-34 ATP molecules.
- The cytochromes deliver the electrons to oxygen, which then picks up two H⁺ ions to form H₂O, a by-product.

Just a few things...

Glycolysis
- Electrons are also accepted by NAD+
- 4 ATP molecules are produced by the pay-off phase and 2 are consumed by the preparatory phase. Therefore a net production of 2 ATP molecules

Krebs cycle
- At VCE level, pyruvate decarboxylation (reactions by which pyruvate is converted to acetyl Co-A) is considered part of the Krebs cycle
- 3 CO₂ per pyruvate molecule - two from the cycle itself and one from pyruvate decarboxylation

Electron transport chain and oxidative phosphorylation
- Not all of the proteins in the electron transport chain are cytochromes. I don't think you'd be penalised for what you wrote though
- The electron transport chain doesn't really "deliver" the electrons to O₂ - they just hang around the end of the chain and are accepted by O₂

[psyxwar]

Just a few things...

Glycolysis
- Electrons are also accepted by NAD+
- 4 ATP molecules are produced by the pay-off phase and 2 are consumed by the preparatory phase. Therefore a net production of 2 ATP molecules

Would you be penalised for not saying 2 "net" ATPs though? I've never seen any instance yet where such information is really necessary.

[Russ]

If they ask "how many ATP molecules are produced", the answer 2 is strictly wrong and indicates a misunderstanding of the process, which is why I will always mark it as wrong. If the question is along the lines of "how many ATP molecules are there after glycolysis" then 2 is fine.

[Scooby]

Would you be penalised for not saying 2 "net" ATPs though? I've never seen any instance yet where such information is really necessary.

I doubt you'd get pulled up for it. It's something they might take a mark off for if the exam's on the easy side and they need a better spread

[Yacoubb]

Are we required to know the historical aspect behind Mendel and his discoveries for the Unit 4 exam? I mean, chapter 10 of Nature of Biology 2 has a large segment devoted to Mendel's findings and all these other scientists. Would it just be best to know about their discoveries. For instance, DNA being double stranded, monohybrid/dihybrid crossing, genes, etc?

[psyxwar]

Are we required to know the historical aspect behind Mendel and his discoveries for the Unit 4 exam? I mean, chapter 10 of Nature of Biology 2 has a large segment devoted to Mendel's findings and all these other scientists. Would it just be best to know about their discoveries. For instance, DNA being double stranded, monohybrid/dihybrid crossing, genes, etc?

NOB has a lot of irrelevant stuff. There's nothing on history on the study design and I doubt it's necessary to know.

[Yacoubb]

NOB has a lot of irrelevant stuff. There's nothing on history on the study design and I doubt it's necessary to know.

Yeah true Thanks for that!

How about the Human Genome Project?

And do we only have to know about Genomics & Proteomics for VCE biology?

[vox nihili]

Yeah true Thanks for that!

How about the Human Genome Project?

And do we only have to know about Genomics & Proteomics for VCE biology?

You don't need to know about the details of the Human Genome project. Distinguishing between genomics and proteomics is about all you'll need to know for this area, I daresay. The study design is very specific about what you need to know, so that'll definitely give you an idea.

[Yacoubb]

Could someone please check that this is sufficient for an exam question asking us to outline the steps of Transcription and Translation:

Transcription:
- The DNA template strand is copied by RNA polymerase in the nucleus.
- A pre-mRNA molecule is formed and then undergoes post-transcription modification.
- The introns (non-coding regions) are removed by splicing, a poly-A tail is added to the 3' end of the mRNA molecule and a methyl-cap is added to the 5'end of the mRNA molecule.
- The mRNA molecule leaves the nucleus via the nuclear pores, entering the cytoplasm.

Translation:
- The mRNA molecule attaches to the ribosomes, where it is translated.
- tRNA (carrying amino acids) anti-codons attach to complementary mRNA molecules.
- The amino acids are assembled into a particular sequence based upon the pre-defined mRNA codon sequence, synthesising the desired polypeptide.

[vox nihili]

VCAA actually asked the transcription last year. I've attached their marking scheme for it.

The translation answer looks good, though you need to emphasise the fact that the mRNA is read at the ribosomes. I think you'd probably have lost a mark on your answer because you haven't clearly started that mRNA's involvement in translation is that it is read at the ribosome. It's not really good enough to say that mRNA is translated at the ribosome if you get what I mean, despite being completely true.

[vox nihili]

I doubt you'd get pulled up for it. It's something they might take a mark off for if the exam's on the easy side and they need a better spread

I wouldn't put it past them. These kind of questions are common in Biology. They like the trick question a bit!

[Yacoubb]

VCAA actually asked the transcription last year. I've attached their marking scheme for it.

The translation answer looks good, though you need to emphasise the fact that the mRNA is read at the ribosomes. I think you'd probably have lost a mark on your answer because you haven't clearly started that mRNA's involvement in translation is that it is read at the ribosome. It's not really good enough to say that mRNA is translated at the ribosome if you get what I mean, despite being completely true.

Okay so would this be better:

Translation:
- mRNA attaches to the ribosome, where it is read and translated.
- tRNA anti-codons attach to the mRNA codons; the tRNA molecules carry amino acids to the ribosomes.
- The amino acids are assembled into a pre-defined sequence to form a desired polypeptide.