AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
The use of hormones to treat infertility (HT only): The eggs are collected from the mother and fertilised by sperm from the father in the laboratory.
After hormone treatment, mature eggs are collected from the mother's ovaries, usually with a fine needle guided by ultrasound.
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
After hormone treatment, mature eggs are collected from the mother's ovaries, usually with a fine needle guided by ultrasound. In the laboratory, sperm from the father are added to the eggs so fertilisation can occur outside the body. Each sperm fuses with an egg to form a zygote, which then divides to form an embryo. The embryos are kept in controlled conditions for a few days before one or more are transferred to the mother's uterus. This is the 'in vitro' part of IVF: fertilisation happens in glassware or a dish, not inside the mother's body. The method allows doctors to check that fertilisation has occurred before implantation. Note that IVF and infertility treatments are Higher Tier only content.
What earns the marks
- Eggs are collected from the mother's ovaries after hormone treatment.
- Sperm are obtained from the father and added to the eggs in the laboratory.
- Fertilisation occurs outside the body, in laboratory glassware or a dish.
- A sperm fuses with an egg to form a zygote, which develops into an embryo.
- The resulting embryo is later transferred to the mother's uterus to continue development.
Common mistakes and how to put them right
Saying fertilisation happens inside the mother.
Put it right by stating that in IVF it happens in the laboratory.
Confusing egg collection with embryo transfer.
Put it right by remembering that eggs are collected first, then fertilised, then embryos are transferred.
Thinking the father's sperm are placed directly into the uterus.
Put it right by stating that sperm are added to eggs in the laboratory.
Exam tips
- Use the phrase 'fertilisation in the laboratory' to make the in vitro step clear.
- Sequence the stages: collect eggs, add sperm, fertilise, culture embryo, transfer embryo.
Try the lesson
The start of the The use of hormones to treat infertility (HT only): The eggs are collected from the mother and fertilised by sperm from the father in the laboratory. lesson, made from checked teaching notes for this specification point.
Have a go first
Where does fertilisation take place during IVF?
Listen
After hormone treatment, mature eggs are collected from the mother's ovaries, usually with a fine needle guided by ultrasound. In the laboratory, sperm from the father are added to the eggs so fertilisation can occur outside the body. Each sperm fuses with an egg to form a zygote, which then divides to form an embryo. The embryos are kept in controlled conditions for a few days before one or more are transferred to the mother's uterus. This is the 'in vitro' part of IVF: fertilisation happens in glassware or a dish, not inside the mother's body. The method allows doctors to check that fertilisation has occurred before implantation. Note that IVF and infertility treatments are Higher Tier only content. A strong answer earns marks for these points. Eggs are collected from the mother's ovaries after hormone treatment. Sperm are obtained from the father and added to the eggs in the laboratory. Fertilisation occurs outside the body, in laboratory glassware or a dish. A sperm fuses with an egg to form a zygote, which develops into an embryo. A common slip: Saying fertilisation happens inside the mother. Instead, stating that in IVF it happens in the laboratory. Exam tip: Use the phrase 'fertilisation in the laboratory' to make the in vitro step clear.
See it
Put it in order
Put these steps in the order they happen.
- 1. Mature eggs collected from the mother's ovaries
- 2. Sperm from the father added to the eggs in the laboratory
- 3. Fertilisation outside the body
- 4. Sperm fuses with an egg to form a zygote
- 5. Zygote divides to form an embryo
- 6. Embryos kept in controlled conditions for a few days
- 7. Embryo transferred to the mother's uterus
- 8. Hormone treatment
Key words
Say what each word means before you turn the card.
In vitro fertilisation
Try answering aloud or in your head before turning the card.
Fertilisation
Try answering aloud or in your head before turning the card.
Zygote
Try answering aloud or in your head before turning the card.
Embryo
Try answering aloud or in your head before turning the card.
See every definition
- In vitro fertilisation
- Eggs are collected from the mother and fertilised by sperm from the father in the laboratory.
- Fertilisation
- Each sperm fuses with an egg to form a zygote, which then divides to form an embryo.
- Zygote
- Formed when each sperm fuses with an egg, it then divides to form an embryo.
- Embryo
- Formed when the zygote divides, it is kept in controlled conditions for a few days before transfer to the mother's uterus.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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