Puberty and the menstrual cycle Cambridge IGCSE Biology (9–1) revision
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In plain words
At puberty the sex hormones switch on, and the body changes from a child's to an adult's. In girls, a monthly cycle begins: the uterus builds up a thick lining ready for a baby, an egg is released, and if no baby starts the lining is shed and it all begins again.
Three things to know
- Testosterone (from the testes) and oestrogen (from the ovaries) cause the secondary sexual characteristics at puberty: in boys a deeper voice, facial hair and more muscle; in girls breasts and wider hips; in both, body hair.
- The menstrual cycle lasts about 28 days. The lining of the uterus breaks down and is lost (menstruation), then is repaired and thickens. An egg is released about day 14 (ovulation). If the egg isn't fertilised the cycle starts again.
- Hormones run the cycle. FSH makes an egg mature. Oestrogen repairs the uterus lining. LH triggers ovulation. Progesterone keeps the lining thick.
Tips and tricks
- Day 1 is the first day of bleeding. Ovulation is around day 14.
- Oestrogen builds the lining up; progesterone keeps it there. When progesterone falls, the lining breaks down.
It lands in your notebook with its questions as flashcards.
Puberty and the menstrual cycle: 5 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
Which hormone causes the changes in girls at puberty?
It is made by the ovaries.
About how long is the menstrual cycle?
It varies from person to person.
What is ovulation?
It happens around the middle of the cycle.
Which hormone keeps the uterus lining thick?
It stays high during pregnancy.
What happens during menstruation?
It marks the start of a new cycle.
Quiz
5 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
3 questions, 7 marks. Write your answers on paper, then check them.
Puberty and the menstrual cycle
Cambridge IGCSE Biology (9–1) 0970 · 7 marks · papermunch.org
Name ______________________________ Date ______________
State three changes that happen to a boy's body at puberty.[3]
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Any three: voice deepens; hair grows on the face and body; muscles develop; testes start to make sperm; the penis and testes grow.
Describe what happens to the lining of the uterus during the menstrual cycle.[2]
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It breaks down and is lost during menstruation, then is repaired and becomes thick again, ready to receive a fertilised egg.
State the function of oestrogen and of progesterone in the menstrual cycle.[2]
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Oestrogen causes the lining of the uterus to be repaired and thicken. Progesterone maintains the thick lining.
Answers: Puberty and the menstrual cycle
- 1. Any three: voice deepens; hair grows on the face and body; muscles develop; testes start to make sperm; the penis and testes grow.
- 2. It breaks down and is lost during menstruation, then is repaired and becomes thick again, ready to receive a fertilised egg.
- 3. Oestrogen causes the lining of the uterus to be repaired and thicken. Progesterone maintains the thick lining.