VCE Biology Question Thread

[vox nihili]

how is it that 6O₂ molecules can enter the electron transport chain, and 6H₂O molecules be produced

it seems that 12 oxygen atoms go in, and only 6 come out.

12H2O come out, but 6H2O are used as part of the reaction. So we just cancel out the 6.

[Scribe]

Hey guys,

Is red light or blue light best for photosynthesis?

Thanks!

[Poet]

Hey guys,

Is red light or blue light best for photosynthesis?

Thanks!

Red. All of the red light is absorbed, but only most of the blue.

edit: I had to put a smiley in, it sounded like I was fed-up without one haha

[Scribe]

Red. All of the red light is absorbed, but only most of the blue.

edit: I had to put a smiley in, it sounded like I was fed-up without one haha

Thank you very much. My hypothesis for my experiment was that blue light would be best for photosynthesis but I guess it's okay for my hypothesis to be wrong. Your explanation made a lot of sense.

[Mr West]

should I be including ADP + Pi and ATP in my overall equations for aerobic and anaerobic respiration

[PhoenixxFire]

Yep

[randomnobody69420]

If photosynthesis occurs in a solution, the solution will become alkaline. Why is this the case?

[darkz]

If photosynthesis occurs in a solution, the solution will become alkaline. Why is this the case?

Well assuming the rate of photosynthesis exceeds the rate of respiration, therefore more CO2 is being consumed and O2 produced. Therefore there is less CO2 in the solution (converted into organic carbon in the form of glucose), therefore there is less carbonic acid (which forms when CO2 dissolves in water) and therefore the solution will become more alkaline.

[vox nihili]

Well assuming the rate of photosynthesis exceeds the rate of respiration, therefore more CO2 is being consumed and O2 produced. Therefore there is less CO2 in the solution (converted into organic carbon in the form of glucose), therefore there is less carbonic acid (which forms when CO2 dissolves in water) and therefore the solution will become more alkaline.

This is a really excellent answer, nailed it.

Just want to highlight what you said about the rate of photosynthesis being higher. This is often not the case. In many the solution becomes more acidic! There's actually an experiment a lot of students do using phenol red indicator where this problem pops up.

[PopcornTime]

Discuss a reason for a cell committing apoptosis by mitochondrial pathway?


Discuss a reason for a cell committing apoptosis by death receptor pathway?

Thanks.

[vox nihili]

Discuss a reason for a cell committing apoptosis by mitochondrial pathway?


Discuss a reason for a cell committing apoptosis by death receptor pathway?

Thanks.

Would really recommend having a crack at your questions or giving a bit of context about what you don't understand rather than copying them here verbatim.

[darkz]

Discuss a reason for a cell committing apoptosis by mitochondrial pathway?


Discuss a reason for a cell committing apoptosis by death receptor pathway?

Thanks.

The mitochondrial pathway is generally for when the cell is stressed by disease or serious damage
The death receptor pathway is generally for the death of excess cells, old cells or cells selected by the immune system

[Al Dem]

Need help completing this question:
What is the nature and purpose of the major histocompatibility complex (MHC)?

Any help is much appreciated

[PhoenixxFire]

Hey, you would learn more if you attempted the question yourself first, and it makes it easier for us to see what you don't know rather than just answering the question for you. How about you tell us what you already know about MHC and then we'll tell you what you're missing.

[Al Dem]

Hello, extremely sorry for the late reply!!
This is what I know so far:
Firstly, each cell displays each own unique marker on its surface (antigens)
MHC codes for a group of proteins that are found on the surface of cells and these group of proteins are able to differentiate between non-self and self antigens.
If a pathogen comes along, bearing non-self antigens (antigens that doesn't come from the body), then the MHC proteins on a cell (any cell?) will then identify this as foreign as it wont be able to recognize the surface antigens on the cell; thus initiating an immune response.
If a substance comes along bearing self antigens (antigens that comes from the body) then the MHC proteins on a cell (any cell?) will be able to identify this as non-foreign as it will be able to recognize the surface antigens on the cell
Purpose of MHC= to differentiate between non-self and self anitgens
Nature of MHC=  found on all cells?

*there are two types of MHC
- class 1 and class 2

Appreciate any help