Edexcel iGCSE Biology-4.13 Development of Secondary Sexual Characteristics- Study Notes- New Syllabus
Edexcel iGCSE Biology-4.13 Development of Secondary Sexual Characteristics- Study Notes- New syllabus
Edexcel iGCSE Biology-4.13 Development of Secondary Sexual Characteristics- Study Notes -Edexcel iGCSE Biology – per latest Syllabus.
Key Concepts:
4.13 understand the roles of oestrogen and testosterone in the development of secondary sexual characteristics
Roles of Oestrogen & Testosterone in Secondary Sexual Characteristics
🌱 Introduction
Secondary sexual characteristics = features that appear at puberty but are not directly involved in reproduction.
Controlled by sex hormones: Oestrogen → female, Testosterone → male.
👩 Oestrogen (Female)
- Produced by: Ovaries
- Main roles during puberty:
- Breast development → growth of mammary glands
- Widening of hips → pelvis changes for childbirth
- Growth of pubic and underarm hair
- Menstrual cycle initiation → prepares reproductive system for fertility
👨 Testosterone (Male)
- Produced by: Testes
- Main roles during puberty:
- Growth of facial, pubic, and underarm hair
- Deepening of voice → growth of larynx and vocal cords
- Increased muscle mass & strength → broader shoulders
- Growth of testes and penis → maturation of male reproductive organs
- Sperm production → enables fertility
📊 Summary Table
| Hormone | Produced by | Secondary Sexual Characteristics | Key Effects |
|---|---|---|---|
| Oestrogen | Ovaries | Breast development, pubic hair, widening hips | Prepares female for reproduction |
| Testosterone | Testes | Facial & body hair, deep voice, muscle growth, penis & testes growth | Prepares male for reproduction |
📌 Quick Recap
– Oestrogen → female puberty: breasts, hips, pubic hair, menstruation.
– Testosterone → male puberty: hair, deep voice, muscles, penis & testes growth.
– Both hormones trigger secondary sexual characteristics → signal sexual maturity.