Moskva

Moskva thank you so much for your explanation.

Moskva God Thank you both of you for continuously responding! Makes sense

Moskva thanks so much for your help! appreciate it

Hair out - Stand Atlantic

-jinx_58

Sorry there chimichurri I missed that second part! Moskva Is right!

In Photosynthesis: water is split using sunlight; and this releases electrons. These electrons are used to load NADP+ into NADPH. Also, hydrogen ions (H+) are released. These build up on one side of the membrane, creating a 'proton gradient'. (Since there is a lot of them on one side, they want to diffuse to the otherside). They then pass through this protein called ATP Synthase, which acts like a watermill; adding the third phosphate group to ADP; forming ATP!

This ATP is then used up in the light independent stage - which produces glucose.

So while photosynthesis does produce ATP; it's only in the first light dependent stage. There is none left over at the end!

This may sound similar to the Electron Transport Chain! In fact: it is! Except the direction of H+ ion flow is the opposite, and other reactions happen (Such as FADH, etc...) and the H+ ions come from the NADH/FADH produced in the krebs cycle etc... (instead of water).

Moving back a bit, during glycolysis (when glucose is split); it produces two 'pyruvate' molecules;
The thing is, it also takes two ATP to do this. So it is really a net 2 ATP produced (as it takes 2, but makes 4). Note that the atoms in glucose aren't being made into ATP; it's just the electrons!

Hence in photosynthesis: Sunlight & Water --> e^- --> ATP....... --> Glucose
And in Cellular Respiration: Glucose --> e^- --> ATP

So it's the electrons from ATP that are transferred. Not the ATP molecules!

I don't think you need to know all that btw...

chimichurri

C4 plants separate the initial carbon fixation stage and the rest of the Calvin cycle over space. In the mesophyll cells, a 4-carbon molecule called oxaloacetate is produced via the help of the enzyme PEP carboxylase. Oxaloacetate is then converted into another 4-carbon molecule called malate. Malate is then transported to the bundle-sheath cells and is broken down to release carbon dioxide, which can then enter the Calvin cycle in a similar manner to C3 photosynthesis light-independent processes. Therefore, C4 plants are more efficient than C3 plants in dry conditions because they can capture more CO2 in less time and the stomata can stay closed for longer to reduce water loss. PEP carboxylase also prevents photorespiration occurring as it has no affinity for binding with oxygen.

CAM plants separate the initial carbon fixation stage and the rest of the Calvin cycle over time. The stomata opens at night to bring in CO2. PEP carboxylase fixes the CO2 to form oxaloacetate, which is then converted into malate or another organic molecule. The molecule is then stored in the vacuoles until daytime. Once it is daytime, the stomata does not open (prevents water loss) but the plant can still photosynthesise by using the malate/organic molecule that has been transported out of the vacuole, which breaks down to release CO2. This CO2 then enter the Calvin cycle in a similar manner to C3 photosynthesis light-independent processes. Therefore, CAM plants are also more efficient than C3 plants in dry conditions because they can capture more CO2 in less time, and allow the stomata to open for effective exchange over night whilst ensuring that water is not lost during the day (due to increased temperatures during the day causing more water loss). PEP carboxylase also prevents photorespiration occurring as it has no affinity for binding with oxygen.

Why is water loss a problem? The stomata closes, meaning CO2 cannot enter and O2 cannot exit, causing photorespiration to increase. This is a problem for C3 plants who have no mechanisms to prevent this. C4 plants prevent this by capturing more CO2 in less time and therefore closing their stomata for longer (of course, stomata will still open to release O2, but since more CO2 is present anyway in comparison to O2, the rate of photorespiration will still decrease). CAM plants open their stomata at night to reduce water loss.

Not sure if this will be helpful because it's quite in depth. In summary, both C4 and CAM plants aim to prevent water loss by either separating carbon fixation and the rest of photosynthesis over space or time. This is to increase the amount of CO2 present, reduce water loss, and reduce the amount of O2 present (to therefore reduce photorespiration).

chemistry1111
"Interferons are a group of signalling proteins made and released by host cells in response to the presence of several viruses. " - Wikipedia

They are sought of like a 'help me' flag. They aren't specific to the virus (hence not part of the adaptive immune response) - and they aren't a type of cell. Rather, they are a protein (like cytokines).

"It is now known that type I IFNs are cytokines produced in response to viral, bacterial, and fungal pathogens, as well as parasites." - Source

I presume it's all types of pathogens - but for written responses, probably just mention for viruses.

chemistry1111
I remember having this exact same question last year lmao.

In reality - I think it's both. An antibody could bind to the capsid (protein coat) of the virus, or even the antigens it leaves on the membrane of the infected cell. But I think, for VCE anyway, it's best to pretend that this doesn't happen.

So if they ask a question about a virus, don't go talking about the humoral immune response.

UNLESS they are referencing an anti-body level graph for vaccinations. (Primary exposure, secondary expose, etc...)

Maybe someone else can give a more definite answer, but my suggestion would just be to work out the vibe of the question, and go from there...

Good luck with your year!

Moskva
also you said that "All pathogens (with the exception of prions) are subject to Adaptive Humoral Immunity response", does this mean virus included as well, as I thought they typically followed cell mediated. If a virus has infected cell it is ...

Moskva
The body already contains Memory B cells from your previous infection, thus recognising the pathogen's antigen and starts creating IgG antibodies. This happens at a faster rate than the first exposure as the body develops memory B cells for the pathogen during the primary immune response.

Moskva

Metalanguage. Metalanguage. Metalanguage. This is very important, especially for units 3/4. I can guarantee that most of examiner's report mentions students most of the time don't know their metalanguage. All the metalanguage you need to know is in the study design. It also contains what you need to know for unit 2 as well.

Moskva I reckon a good bet is to take a look at the metalanguage listed on the study design (see pages 9-10 for Units 1&2, and pages 17-18 for Units 3&4). IMO if you're across these terms, that will go a decent way to success.

krystal

also I want to do biology because i have no interest in no other subject

I didn't study Bio, but this sounds like a pretty good reason to me to continue with the subject!

Hey Moskva!

Year 11 tend to have an edge in terms of having more time available to study but can struggle more when it comes to how to answer questions. My advice for you to is focus on where you are losing marks and to put in place a strategy for addressing those areas. E.g. if you tend to make silly mistakes but finish early, try slowing down the rate at which you go through assessments. If you're not sure where you're losing marks now is a good time to start keeping track.

Moskva Because you already have memory B and T cells from the first infection which coordinate a quicker, more effective and longer-lasting 2° immune response upon re-exposure to the antigen