Explore how sperm and secondary-oocyte ultrastructure—including mitochondria, flagellum, zona pellucida and nutrient-rich cytoplasm—supports human fertilisation in IB Biology HL B2.3.10.
Draw a labelled diagram of a mature human egg.
Award [1] for each structure accurately drawn and correctly labelled.
a. haploid nucleus;
b. cytoplasm - with nucleus-to-membrane distance >4 times nucleus diameter;
d. cortical granules - needs to be drawn in vicinity of plasma membrane;
e. plasma membrane - shown as a single line and approximately circular overall;
f. polar cell / (first) polar body - needs to be drawn outside the egg cell;
g. zona pellucida / layer of gel (outside the cell membrane);
h. follicle cells / corona radiata (outside the cell membrane);
i. size shown as 100μ m/0.1 mm;
(accept 90μ m to 120μ m )
Editorial correction: mature human oocytes lack centrioles. Do not award the former centriole criterion. Award for the remaining correctly drawn and labelled structures, up to the original maximum.