Fertilisation, birth control and sexually transmitted infections
Every person begins as one cell. In fertilisation the nucleus of a sperm fuses with the nucleus of an egg, usually in an oviduct. The new cell divides, settles into the uterus, and is fed through the placenta for about nine months. This page also covers birth control and two infections spread by sex.
By the end of this page you can
- Explain how the placenta supports a baby, compare birth control methods, and describe HIV and gonorrhoea
- Describe fertilisation, implantation, and the jobs of the amnion, placenta and cord
- Put the journey from sperm to implantation in order
- Define fertilisation, zygote, implantation, placenta and contraception
- Weigh up the pill and the condom
Goals tick themselves off as you try the activities below.
Photo: Eugene Ermolovich (CRMI), CC BY-SA 3.0, via Wikimedia Commons. Cropped, resized, JPEG q70.
A human egg is one of the largest cells in the body, about 0.1 mm across. Sperm are far smaller, and swim to meet it.
How often it shows up in past papers
Paper 1 counts come from our past-paper bank of CSEC Biology Paper 1s. Paper 2 is not included yet.
A growing baby, choices, and staying safe
How a baby is kept alive, how pregnancy is prevented, and two infections to know. Tap each card.
Each stage and structure, its job
Tap each one to see what it does.
What does it do?
Tap a stage on the list to see its job.
The placenta keeps the two bloods apart but close, so substances diffuse across, including harmful ones: alcohol, nicotine, some drugs, and viruses such as HIV.
From sperm to implantation
Put these in order. Drag or tap each card into its slot.
Where are the sperm released?
Seven terms to know cold
Say what each term means before you flip the card. Placenta answers need “diffuse” and “bloods do not mix”.
Six quick questions, then a real one
Pick an answer to see why it’s right or wrong.
Fertilisation in humans normally takes place in the
The amniotic fluid
Which substance passes from the mother to the fetus across the placenta?
Which method of birth control also protects against STIs?
HIV weakens the body because it destroys
Gonorrhoea can be cured with antibiotics because it is caused by
exam style · 4 marks
Give ONE advantage and ONE disadvantage of the contraceptive pill and of the condom.
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Practice questions are written by My V.I.P. Academy. They are not official CXC papers.