I need help for once again, another question:

Eukaryotic cells have a single circle of mitochondrial DNA consisting of approximately 16.5 kilobases. Mitochondrial DNA is useful in establishing evolutionary relationships between individuals because:
A) it is only present in female gametes
B) recombination occurs at a regular rate
C) it is present in smaller amounts than nuclear DNA
D) substitution mutations occur at a greater rate than nuclear DNA
The answer is B and I have no idea why

Taaaa76 oxygen binds to haemoglobin, so I'm assuming the answer is A. This might be an old exam questions, since I don't recall body systems being part of the new study design.

      Taaaa76 okay so when a virus enters a cell, the cell will release interferons as a warning signal for other neighbouring cells. Basically, it's warning its neighbours that a virus is in the body, and therefore A wouldn't be correct. Complement proteins will be released to try and recruit more leukocytes to the site of infection, so B wouldn't be correct. Production of lymphocytes, aka T and B cells will increase as antigen-presenting cells active the humoral and cell-mediated responses, so D is also incorrect. Apoptosis however is controlled cell death. This is used by the body to get rid of body cells that are damaged, dying, potentially cancerous, etc. Cells infected by viruses undergo lysis, at least according to VCAA (biology is a lot more complicated), not controlled cell death initiated by the body itself. Therefore, I reckon C is probably correct (I might be wrong though).

          _sophiestudies_

          The answer is B i shouldve clarified, my bad.
          Also, dont virally infected cells also undergo apoptosis? Like a natural killer cell and cytotoxic t cell both induce apoptosis in an infected cell right?

              Taaaa76 okay yes that does make sense. Apoptosis would take place because of natural killer cells and cytotoxic T cells. My bad. You know what, it's a dumb question ahaha because complements would be released. Is this a VCAA question?

                  Taaaa76 oh it's about carbon dioxide ahaha. I'm currently studying haemoglobin at uni so that's why I messed that up. Yes, CO2 is carried by bicarbonate ions in plasma, but I don't think you'll need to know about that.

                      Taaaa76 hmm that might be why. In uni we learn that the complement system is important for many pathogens, so I have no clue why B would be correct. Since it wasn't a VCAA question, I wouldn't worry about it.

                          Hey guys, does anyone know if we need to know how monoclonal antibodies are produced under the current study design?

                            unknown312
                            from the vcaa q&a document is says that "students should be able to apply their knowledge of extracellular and intracellular threats to other areas of the study design, such as the development of monoclonal antibodies to treat cancer, and other unfamiliar situations and contexts." because it says development that might mean we have to know the steps to prodiuce them. but honestly I would just try to memorise the steps because I feel like they are quite easy to understand.
                            the diagram on this article linkbelow helped me remember them. hope this helps you!
                            https://www.moleculardevices.com/applications/monoclonal-antibody-production

                              hey, does anyone know around what exam score you need to get around a 45? 🙂

                                soph43

                                I think this website would help:
                                acedvce.com/what-do-i-need-to-get-an-a-in-vce/

                                  Hey guys, does the sgRNA bind to the PAM site or does it bind to a different target sequence? If so, what does the Cas-9 enzyme bind to, because I keep getting different answers from teachers and the internet??

                                    Taaaa76 It contains gRNA, which includes the mRNA CRISPR sequence (with viral DNA), and the endonuclease Cas9.

                                        Laila
                                        The complementary single-guide RNA (sgRNA) is artificially produced in a lab and acts as a template of the target DNA sequence. It will guide the Cas9 to cut the target DNA sequence. However for the Cas9 endonuclease to perform its function it needs to recognise the PAM sequence (very short sequence) adjacent to the target DNA sequence. The PAM sequence acts as a binding site for the Cas9 endonuclease. Once it binds it will perform its function of cutting the target DNA sequence. Have a look at the 2023 NHT Bio exam on CRISPR.

                                            Also I don't know if this is allowed to be asked, but anyone have any predictions for the VCE Bio exam questions this year aha.