Hey guys, just gonna word-vomit a few questions here because these are areas that I've been consistently getting confused about in practice exams, and I haven't found much information online or in my textbook that was helpful:
1. Are there other regulatory genes that regulate BMP4 genes? My teacher said that BMP4 genes are the top of the hierarchy and thus there are no genes that control it, but how would BMP4 gene be regulated then? (as in how much, when, location, etc.) I also read somewhere on atarnotes where someone said that regulatory genes control BMP4 genes and that mutations occur in these regulatory genes, affecting its expression, so I'm a little confused. With regards to BMP4 as well, I don't think my definition of it is adequate/clear enough, so could someone tell me what I should add or change?: BMP4 is a master gene that produces BMP4 signalling molecule which switches on genes required for cellular differentiation in embryonic (stem?) cells to produce the specific structures of an organism
2. With allopatric speciation, is it accurate to say that there was variation in a population which allowed them to colonise different habitats, and that after they were separated by a geographical barrier, no gene flow occurred and they accumulated mutations due to the different selection pressures in their respective environments, leading to the inability to create viable, fertile offspring? Would this lead to a change in allele frequencies but not gene pool because the alleles are still present, it's just that the alleles correlating to the favourable trait have increased in proportion over other alleles?
3. In the Out of Africa theory, did H.sapiens evolve from H.erectus or H.heidelbergensis? Is it true to say that some H. erectus and H. heidelbergensis populations stayed in Africa to give rise to H.sapiens, while other populations of H.erectus and H.heidelbergensis migrated elsewhere in the world? And that the H.heidelbergensis then evolved into Neanderthals and Denisovans whilst the H.erectus just... died out? (taking a wild guess here hey)
4. Final question lol! I recently did the 2017 exam (and found it much harder than the previous ones
), did VCAA change the format of Bio exams? It seemed quite different in style to the other previous exams (esp. that 6(?) marker question on megafauna)
Edit: Forgot to mention - in radiometric dating, is it the RATIO of the isotopes that is being measured and used to determine the age of a fossil/rock or is it just the amount of an isotope (e.g. in potassium-argon dating, is it the ratio of Potassium-40 to Argon-40 that is being measured and compared to the ratio in new rock, or just the amount of Potassium-40 or Argon-40 created (and no ratio is looked at?) idk if that makes any sense haha