Draw a labelled diagram of the adult male reproductive system.

Describe the role of sex chromosomes in the control of gender and inheritance of hemophilia.

Discuss the ethical issues associated with IVF.

Award [1] for each of the following structures clearly drawn and correctly labelled.
Adjacent structures mentioned in each marking point must be recognizable in the drawing for the mark to be awarded, but need not be correctly labelled.
testes/testis – shown inside scrotum;
scrotum – shown around testes;
sperm duct/vas deferens – shown connected to urethra;
penis/erectile tissue – penis shown with erectile tissue inside;
urethra – shown linking bladder / upper side of prostate gland to end of penis;
epididymis – shown connected to sperm duct;
seminal vesicle – shown branched off sperm duct (not off the urethra);
prostate gland – shown positioned where sperm duct connects with urethra;
bladder – showing urethra leading away;

two sex chromosomes are X and Y;
one sex chromosome inherited from each parent;
XX results in female;
XY results in male;
sex determined by sperm/father;
sex-linked genes are those located on the sex chromosomes / usually refers to genes on X chromosome;
recessive sex-linked traits appear more frequently in males since they only have one X chromosome;
hemophilia is an example of a gene located on the X chromosome/sex-linked;
female carriers are heterozygous / X^HX^h;
males with hemophilia are X^hY / normal males are X^HY;
sons (of carrier females) have 50 % probability of showing the trait (even if father is normal);
daughters (X^hX^h) of hemophiliac father and carrier mother can be affected / daughters who receive an affected X from each parent will have hemophilia;
The points above can be gained by annotated Punnett squares.
Candidates may introduce a lettering system for haemophilia genotypes which does not include H and h. Accept other letters for superscripts, but same alphabetical letter should be used throughout, dominant form should appear as upper case letter and recessive as lower case letter.

To award full marks, discussion must contain both pro and con considerations.

pros/positive considerations: [3 max]
chance for infertile couples to have children;
decision to have children is clearly a conscious one due to difficulty of becoming pregnant;
genetic screening of embryos could decrease suffering from genetic diseases;
spare embryos can safely be stored for future pregnancies/used for stem cell research;

cons/negative considerations: [3 max]
IVF is expensive and might not be equally accessible;
success rate is low therefore it is stressful for the couple;
it is not natural/cultural/religious objections;
could lead to eugenics/gender choice;
could lead to (unwanted) multiple pregnancies with associated risks;
production and storage of unused embryos / associated legal issues / extra embryos may be used for (stem cell) research;
inherited forms of infertility might be passed on to children;
Accept any other reasonable answers.

The drawings of the male reproductive system were generally poor. Organs were suspended and not connected to one another in many drawings, while in others they were improperly connected. The relative sizes of structures showed little sense of proportion.

Candidates usually knew the role of sex chromosomes in controlling gender but were weak explaining how sex-linkage affects the inheritance of hemophilia.  Some stated that dominance changed depending on the gender of the person; others put the gene on the Y chromosome. Punnett squares were evident but had irrelevant crosses. Confusion was apparent over whether hemophilia was a recessive trait, and subsequent lettering systems for genotypes were unclear and muddled.

Since this question involved a discussion of ethical issues associated with IVF, both positive and negative arguments should have been included. This did not always happen. Some candidates limited their answers to only negative arguments such as why IVF was not natural or why it was against religious beliefs and did not expand this. Several candidates wrote about the process of IVF while others confused IVF with artificial insemination or even cloning. Fortunately, there were a few candidates who wrote thoughtful and balanced discussions.