do i need to know the specific amounts of products/inputs for cellular respiration and photosynthesis?

    md2112 It’s not H floresiensis because they tend to have smaller stature so compared to Aboriginal Australians who are much larger, they couldn’t be the ancestor - you can also probably talk in terms of cranial capacity and how it was found much more recently than 50000/60000 years ago when Aboriginal Australians first arrived into Sahul. The only confusion comes with H Denisova and H erectus
    Because it says “fossils from this time period include H erectus” I’d argue that H erectus lived in the same time period as the aboriginal Australians so its not likely to be an ancestor (also considering the lack of similarity of nuclear DNA)
    I feel like although H denisova only shares 4-6% nuclear DNA in common its probably the best answer here accoridng to the information given in the passage

        md2112

        1. Cytotoxic T cells are involved in an adaptive immune response (cell mediated) and they release chemicals like perforins to induce apoptosis in virally infected cells upon binding to the non self antigen presented on MHC 1 markers of the infected host cell
        2. Whereas natural killer cells are involved in the innate immune response. It detects the lack of MHC 1 markers on a host cell and recognises it as “non self” releasing granzymes initiating a death ligand that causes apoptosis

            Also can someone please explain the Q9 C ii) of the 2022 sample exam on mtDNA phylogeny - I kind of get it but not fully- espcially the part about “continuous presence” of aboriginal Australian populations

              md2112 cytotoxic t cells are part of the adaptive cell-mediated response, whereas natural-killer cells are non-specific immune cells part of the innate immune system (second line of defence). Cytotoxic t cells will therefore specifically bind to MHC I markers/antigens it's initial T cell was selected for, whereas natural killer cells will target any foreign MHC I markers it notices on viral infected cells or tumour cells. Also, natural killer cells have killer activation and killer inhibition receptors that indicate whether it kills the cell, whereas cytotoxic t cells are already programmed to kill the cell that they bind to using their t cell receptor.

                md2112 Cytotoxic T cells produced from the expansion and differentiation of the selected T cell are activated by Helper T cells via the release of cytokines, as well as through binding to the first MHC I marker it finds on an infected cell. Both allow it to be activated.

                    guys im confused with the question 1c on the sample exam, it says will the "enzymes for tryptophan sysntehis be produced", can someone please help

                      md2112 the structural genes in the trp operon each code for separate enzymes that are involved in the formation of tryptophan. Here are the details (don't need to know this though):

                      • TrpE and TrpD -> Form enzyme Anthranilate synthase, which converts chorismate (found in the cell) into anthranilate.
                      • TrpC -> Forms enzyme Indole-3-glycerol-photosphate synthase, which converts anthranilate into indole-3-glycerol-photosphate.
                      • TrpB and TrpA -> Forms enzyme Tryptophan synthase, which converts indole-3-glycerol-photosphate into tryptophan.
                        (Requires lots of energy, meaning the process needs to be tightly regulated via attenuation and repression mechanisms).

                      Here in the structure of the trp operon to help as well (would ensure you know this):

                      3' end - Promoter - Operator - Leader (TrpL) - Attenuator - TrpE - TrpD - TrpC - TrpB - TrpA - Trailer - 5' end

                      Hopefully this will help you understand the question!

                          _sophiestudies_ oh that makes sense, so i could simply talk about attenutation, and it produces a trasncirption termination signal which prevents the expresssion of structural genes and so the enzymes aren't produced

                              chemistry1111

                              Humoral response:

                              1. Antigen-presenting cells (i.e. macrophages and dendritic cells) phagocytose pathogens and present its antigens on their MHC II markers. They are then transported to secondary lymphoid tissue.
                              2. The antigens are presented to naïve B cells with corresponding B cell receptors (antibodies). They phagocytose them and present them on their MHC II markers. This causes them to become activated/selected.
                              3. They present the antigens to T helper cells, which bind using their specific T cell receptors. This causes them to become activated/selected.
                              4. T helper cells release cytokines, which stimulate the selected B cell to undergo clonal expansion (proliferate/produce many of itself) and differentiate to form plasma B cells and memory B cells.
                              5. Plasma B cells produce antibodies, which can then be sent to the area of infection to opsonise, agglutinate, naturalise, and/or activate complement proteins.
                              6. Memory B cells provide long-lasting immunological memory, activated when they come in contact with the pathogen again. The rapidly proliferate to form memory plasma B cells that produce larger amounts of antibodies, and more memory cells to strengthen this immunological memory.

                                what is the difference between social implication and biological implication? and also do we need to include that in sympatric speciation gene flow doesnt occur

                                Also do we need to know about BMP4 gene