VCE Biology Question Thread

[Angelx001]

Do we need to know about the lac operon & Barr bodies?

[The Usual Student]

Do we need to know about the lac operon & Barr bodies?

Da hell is a lac operon
I learnt about Barr Bodies in class tho

[FatimaEl]

Da hell is a lac operon
I learnt about Barr Bodies in class tho

I had the opposite reaction, whats barr bodies???
I learnt about lac operon and yeah its an example of gene regulation which you need to know: "the concept of gene regulation (the switching on and off of genes by factors expressed by regulator genes and environmental factors)" (study design)
but i dont think u need to know specific examples (such as lac operon) just know the concept

[The Usual Student]

I had the opposite reaction, whats barr bodies???
I learnt about lac operon and yeah its an example of gene regulation which you need to know: "the concept of gene regulation (the switching on and off of genes by factors expressed by regulator genes and environmental factors)" (study design)
but i dont think u need to know specific examples (such as lac operon) just know the concept

a very brief summary of barr bodies
- Since girls have two X chromosomes
- Only need to express one of them
- Every cell shuts of one of their X chromosome copies
that is the barr body
pretty much it there is probably stuff I forgot but just know what the general concept is, I doubt we will receive any 3+  marker questions on the topic, probably a cheeky multi choice or 1 marker.

[Gogo14]

Can somebody explain the rhesus factor and how it works? Is it similar to ABO blood groups?

[Gogo14]

what are limiting factors that may limit the rate of photosynesis given there is unlimited light?
Are temperature and pH suitable answers/accepted?

[FatimaEl]

Can somebody explain the rhesus factor and how it works? Is it similar to ABO blood groups?

This is a perfect explanation
"Rhesus is a protein that resides on the red blood cells. People who have this protein are considered to be Rhesus positive and if an individual does not have this protein they are termed Rhesus negative.The presence of the protein on the red blood cells is genetically  determined. The Rhesus protein is of a concern during pregnancy as if a Rhesus negative mother has a rhesus positive child and the Rhesus positive proteins in the baby’s blood comes into contact with the Rhesus negative mother’s blood an immune response in the mother is generated, producing antibodies in response to the Rhesus protein (what the mother’s immune system deems as foreign antigens) resulting in implications for the child. This is generally not an issue for the first pregnancy because few if any blood cells from the fetus move across the placenta into the mother. It is during the birthing process whereby the placenta separates away from the uterus wall that a significant number of the baby’s red blood cells cross into the mother’s blood stream whereby the immune response generated results in antibodies being made that reside in her blood stream. During a second pregnancy these antibodies  and memory B cells that have been circulating in the mother’s blood stream since the first pregnancy that are able to pass the placenta into the fetus reacting with the Rhesus proteins on the child causing damage to the tissues and organs.   The baby’s blood cells are destroyed and their contents circulate in the blood stream giving the baby a jaundiced appearance (yellowed skin). This is known as hemolytic disease."

what are limiting factors that may limit the rate of photosynesis given there is unlimited light?
Are temperature and pH suitable answers/accepted?

You can also add water there and carbon dioxide

[hodang]

If it asks us to explain why the genetic code is Universal, can we write:
- Because all organisms use the same nucleotide bases and Codons code for the same amino acid ?

[plsbegentle]

If it asks us to explain why the genetic code is Universal, can we write:
- Because all organisms use the same nucleotide bases and Codons code for the same amino acid ?

First bit is correct but the last bit refers to redundant.(and Codons code for the same amino acid).


I also have a question; can someone explain the replication fork to me?
Thanks

[The Usual Student]

Guys I am super confused

Glycolysis--> THE BREAKING DOWN OF GLUCOSE! like its in the bloody name
Yet VCAA 2007 Exam 1 Multi Choice Q8 says lipids would be broken down before starch is if all glycogen was depeleted. I pressumed the starch was externally consumed from plants.  And I ruled lipids out since they can't be broken down in glycolysis.... yet the answer was friggin lipids.

[eru]

Is it a good idea to memorise the VCAA definitions?

[sweetcheeks]

Guys I am super confused

Glycolysis--> THE BREAKING DOWN OF GLUCOSE! like its in the bloody name
Yet VCAA 2007 Exam 1 Multi Choice Q8 says lipids would be broken down before starch is if all glycogen was depeleted. I pressumed the starch was externally consumed from plants.  And I ruled lipids out since they can't be broken down in glycolysis.... yet the answer was friggin lipids.

You are correct. The question should be worded more like 'what is the next energy source utilised'. Glycolysis is the specific process of breaking down glucose, lipids follow a different pathway (end product is still acetyl CoA, used in the krebs cycle).

[The Usual Student]

You are correct. The question should be worded more like 'what is the next energy source utilised'. Glycolysis is the specific process of breaking down glucose, lipids follow a different pathway (end product is still acetyl CoA, used in the krebs cycle).

Yeah I asked a friend and they said lipids are broken down into glucose first then used in glycolysis? Are we expected to know all this since it seems pretty far out of the study design ( well the exam was from 2007 so it might be a bit different )

[HasibA]

whats the best way to remember the graphs for high conc of enzymes vs low substrate conc etc. and all their variations
i seem to have to rote learn it because i always forget it/ get mixed up with it ah!

also- are we meant to know the term intermediate inheritance..? coming up in company papers haha

[sweetcheeks]

Yeah I asked a friend and they said lipids are broken down into glucose first then used in glycolysis? Are we expected to know all this since it seems pretty far out of the study design ( well the exam was from 2007 so it might be a bit different )

From my reading it appears that it is something not resolved yet, whether lipids can be turned into glucose or not. I would not expect that to be something we should know. Just know that the pathway is carbohydrates (glycogen) --> lipids --> proteins that are utilised for energy.