Human reproduction is sexual. A new life starts when two gametes join. The male gametes are the sperm. They are made in the testes. The female gametes are t...
Question 1 Report
Human reproduction is sexual. A new life starts when two gametes join. The male gametes are the sperm. They are made in the testes. The female gametes are the egg cells. They are made in the ovaries. About once a month an egg is released. It leaves one of the ovaries. It travels along the oviduct. It moves towards the uterus. Here the egg may meet sperm. If a sperm fertilises the egg, it travels on. It reaches the uterus. It sinks into the thick lining. There it can grow into a baby. If it is not fertilised, the lining breaks down. A student was asked about the egg's journey.
(a) Name the male gamete and the organ in which it is made. [2]
(b) Name the part of the female reproductive system in which fertilisation usually takes place. [1]
(c) State what is meant by the term fertilisation. [2]
(d) Describe what happens to the fertilised egg from the moment of fertilisation until it becomes attached to the uterus. [3]
(e) Explain why the lining of the uterus becomes thick each month. [2]
Answer Details
This question is about human gametes, fertilisation and early development.
(a) The male gamete is the sperm [1]; it is made in the testis / testes [1].
(b) Fertilisation usually takes place in the oviduct (fallopian tube) [1].
(c) Fertilisation is the joining / fusion of a male gamete (sperm) nucleus [1] with a female gamete (egg) nucleus [1] to form a zygote.
(d) From fertilisation until attachment to the uterus: the fertilised egg (zygote) divides repeatedly by mitosis to form a ball of cells [1]; it travels down the oviduct towards the uterus [1]; and then becomes attached to (implants in) the thick lining of the uterus [1].
(e) The lining of the uterus becomes thick each month because the thickened lining develops a good blood supply [1], so that it is ready to receive and nourish a fertilised egg / developing embryo if one implants [1].
Exam tip: in part (c) the marks are specifically for the fusion of the two nuclei; writing only "sperm meets egg" without the idea of nuclei fusing risks losing a mark.
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