Hey chimichurri!

I wouldn't worry about the specific chemistry involved.

Just know that they pretty much fulfil identical roles -- acting as electron/proton carriers/donors. With the difference being that NADPH is for Photosynthesis whereas NADH is for Cellular Respiration.

Also it seems like you should revise Cellular Respiration overall 😅 (Glucose is broken down to make energy to synthesise ATP)

    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... 😆

    Secondary responses are extended cellular responses to an antigen utilising specified cells such as Phagocytes and Monocytes while primary responses are shorter lived and more often preventative toward antigens such, (skin, stomach acid etc).

      7 days later

      Moskva sure, its from 2008 exam 1, question 5 b. and yep that does make sense, ig the cells in the tissue would be considered an intracellular pathogen bcos of the mhc 1 markers?

        Hi, RBCs aren't nucleated therefore they don't have MHC 1 markers. So how are they identified as self/non-self? And how can blood transplants be rejected from the recipient's body?

          bioho4

          RBCs don't have MHC/HLA markers but some will have "red cell antigens". Most times these atigens will fall under either type-A or type-B (there are a few minor ones but they are very very uncommon so don't worry about it).

          You may have heard of the term "blood type", which can be either O, A, B or AB (for all intents and purposes).

          • People with type-O blood type have no red cell antigens on their red blood cells.
          • People with type-A blood type have type-A antigens on their red blood cells.
          • People with type-B blood type have type-B antigens on their red blood cells.
          • People with type-AB blood type have both type-A and type-B antigens on their red blood cells

          Ok, due to Immunological Tolerance, and the relatively conservative nature of these A and B antigens, people with a certain blood type will be able to accept any blood with the same or less antigens. Since they are recognised as self. That is to say, a person with type-A blood will be able to accept Type-O (no antigens, less) and Type-A (same) blood; but not Type-B or Type-AB blood.

          Blood transplants are rejected is because the antigens in the transfusion are not recognised as self (i.e. foreign).

          EDIT: just to be extra clear, this is quite a simplified view of blood types, as there are more red cell antigens types than just A and B; rhesus factors also need to be taken into consideration (which is technically just another type of antigen).

          bioho4

          Ah ok I see,

          The VCAA question explicitly states a tissue has entered the body; presumably transplanted but that doesn't really matter.

          And, yes, MHC class 1 on the cells of the tissue is what allows Cytotoxic T Cells to recognise them.

          Also, the cells themselves aren't considered pathogens, just foreign.

            5 days later

            Just want to confirm if my reasoning is right and ask a question about how index fossils are use to date other fossils found in the same strata:

            1. Firstly radiometric dating is utilized to date igneous rock associated with (near) sedimentary layer that the index fossil is found within, percentage of parent isotope is compared to broken down products, hence using stratigraphy it can be inferred that the age of the index fossil = ____.

            2. Using stratigraphy, the fossil found in the same strata is the same age as the index fossil, ____.

            So if the question asked whether using index fossils is absolute or relative (point 2) what would be say?

            Relative - because the age of the fossil is being determined by using the index fossil nearby?

            or Absolute - because the NUMERICAL value of the fossil is known because of the INDEX fossils whose NUMERICAL age is also known?

              Hey tubes!

              1. Firstly radiometric dating is utilized to date igneous rock associated with (near) sedimentary layer that the index fossil is found within, percentage of parent isotope is compared to broken down products, hence using stratigraphy it can be inferred that the age of the index fossil = ____.

              Here you must mention that calculations are made based on the half life of the particular radioisotope measured in the radiometric dating; otherwise, how does the ratio of parent to daughter nuclei help?

              It might also be good to mention the type of radiometric dating technique you are referring to (i.e. K-Ar dating), as they all have ranges.

              1. Using stratigraphy, the fossil found in the same strata is the same age as the index fossil, ____.

              Yes, you are correct here as well, but because the unknown fossil is more often than not in another strata from the index fossil used, the index fossils are often used in conjunction with the principle of superposition (which states that rock strata are arranged in a order of progressing age, with the newest at top, in normal conditions). That is to say, if there is a fossil of unknown age and it is found below an index fossil, it can be inferred that the unknown fossil is older than a certain age (i.e. that of the index fossil); and vice versa.

              So if the question asked whether using index fossils is absolute or relative (point 2) what would be say?

              Relative - because the age of the fossil is being determined by using the index fossil nearby?

              or Absolute - because the NUMERICAL value of the fossil is known because of the INDEX fossils whose NUMERICAL age is also known?

              Relative. If an index fossil is used it is always relative. Because it is in relation -- or in other words, relative to -- the index fossil (also links back to my previous point that the unknown fossil is more often than not, in a different rock strata to the index fossil, so the approximate numerical age is not known anyway).

              Hope this helps 😉 .

                Moskva
                Thank you it makes sense. But this VCAA question is kind of confusing, like I understand the answers but I'm confused on how to categorize it. 2018 NHT 7 b and c in which it asks how the ABSOLUTE AGE can be determined using the ancient mollusk (similar to index fossils in the sense of providing RELATIVE age), so it is a relative dating technique that can provide ABSOLUTE AGE or it is an absolute dating technique.

                Thank you once again

                • God replied to this.

                  tubes

                  Hi Tubes!

                  • Absolute Age: A numeric age measured specific to that fossil/rock/sample.
                  • Relative Age: An age inferred based on nearby rocks/fossils.

                  An absolute age can be used to determine a relative age for another rock/fossil. Not the other way around.

                  Hope this helps!

                    God
                    Hi,
                    I agree with your first point. But in that VCAA question by determining absolute age of the igneous rock you could determine the absolute age of the ancient mollusk (as specified in the stem) by using relative dating techniques, since its found in the same stratum (after first using absolute dating techniques on the igneous rock), so would finding the relative age of the ancient mollusk (in the same stratum as the dated igneous rock) be used to determine its absolute age of 50 my???? So is it also possible for it to be the other way around????
                    So all in all what technique would it be: absolute or relative???

                      tubes

                      Question Stem: The scientists justified that the P. portelli fossil is 50 million years old by referring to fossils of several ancient molluscs.
                      Exam Report: The radiometric dating is done on igneous rock layers associated with the sedimentary layers in which the fossil molluscs have been found elsewhere in the world

                      Ahhh...I think I understand what you're saying. In this case, it would be a relative age of the fossil. (Made more accurate as the index fossil is tested many times in many places) (The age of the rock would be absolute)

                        Hello again tubes

                        But in that VCAA question by determining absolute age of the igneous rock you could determine the absolute age of the ancient mollusk (as specified in the stem) by using relative dating techniques, since its found in the same stratum (after first using absolute dating techniques on the igneous rock),

                        You misinterpreted the VCAA question (/suggested answer).


                        Scientists take samples of igneous rock from igneous rock strata above and below the mollusc fossils. Then they use the ratio of Potassium-40 to Argon-40, and the half-life value of Potassium-40 to calculate the age of these igneous rock strata. Since the mollusc is in between these two strata of igneous rock scientists can kind of average the two values and get an approximate age* of the mollusc fossil. This is absolute dating.

                        *I know the name of the dating method would suggest that it yields an absolute value, but unfortunately it is not always possible to directly date a fossil.

                          7 days later

                          Hi guys, I was just wondering if any of you could review and guide me with answering Question 9 of the sample examination for 2022 VCE.

                          a) Homo heidelbergensis that evolved into Homo sapiens 300,000ya in Africa and then migrated to Australia 50,000 ya. Already present before the arrival of the ancestors of Indigenous Australians was Homo erectus - an earlier hominin- that had previously migrated out of Africa and had diverged into Homo floresiensis in Indonesia also coexisted with Homo sapiens.

                          b) Migration to Australia occurred in 2 distinct pathways, were one group reached and travelled along the East coast 40,000 ya and the 2nd group travelled across the western coast and settled 41000, because the 2 main groups were geographically isolated by Australia's mainland, gene flow was limited and hence different mutations occurred and accumulated in each population's genome

                          c)i) Evidence of art (cultural evolution) such as cave paintings
                          The presence of stone tools

                          c)ii) The large genetic variation in mtDNA indicates that a long time had elapsed since migration hence the time for mutations to accumulate, supporting a continuous presence in Australia as well as in discrete areas as many different mutations occurred in specific isolated population and hence accumulated because of the lack of gene flow leading to 111 mtDNA genomes to diverge

                          Thanks