Suggest one difficulty that could occur as a consequence of using ICSI.
Before ICSI, infertile women are given injections of human follicle stimulating hormone (hFSH) every day to encourage several ovarian follicles to grow and mature. The hFSH used may come from urine (u-FSH) or be recombinant hFSH (r-hFSH) produced by genetically modified mammalian cells. Each hFSH molecule contains two different polypeptide chains, $\alpha$ and $\beta$. The genes for the $\alpha$ and $\beta$ chains of hFSH, together with their promoters, have been inserted into mammalian ovary cells. Explain why promoters need to be transferred with desired genes when producing a genetically modified cell.
Once hFSH treatment is complete, oocytes are taken from mature ovarian follicles and checked to confirm that they have reached metaphase II of meiosis. Describe how an oocyte in metaphase I of meiosis can be told apart from one in metaphase II of meiosis. You may use labelled diagrams to support your answer.
Two sets of women being prepared for ICSI were injected daily with either r-hFSH or u-hFSH. Their treatment outcomes are shown in Table 2.1. With reference to Table 2.1, compare the effects of treatment with r-hFSH and u-hFSH and suggest an explanation for any differences.
While the two groups of women described in (d) were receiving daily injections of FSH, their blood oestrogen concentrations were recorded. The results are shown in Fig. 2.1. With reference to Fig. 2.1, compare the results for the two groups of women.
Describe the role of oestrogen in preparing these women to receive ICSI.
Explain how the evidence in Fig. 4.2 indicates that the foothill populations and the lowland populations of agile frogs are genetically different.
Suggest how these genetic differences could help improve the survival chances of the foothill populations in their natural habitat.