Edexcel iGCSE Biology-2.26 energy requirements- Study Notes- New Syllabus
Edexcel iGCSE Biology-2.26 energy requirements- Study Notes- New syllabus
Edexcel iGCSE Biology-2.26 energy requirements- Study Notes -Edexcel iGCSE Biology – per latest Syllabus.
Key Concepts:
2.26 understand how energy requirements vary with activity levels, age and pregnancy
Energy Requirements in Humans
📝 Introduction
Every person needs energy for basic functions like breathing, circulation, movement, growth, and repair.
The exact energy requirement depends on factors such as activity level, age, and pregnancy.
⚡ Factors Affecting Energy Requirements
1. Activity Levels
- More active → more energy needed.
- Examples:
- Athlete or manual worker → high energy demand.
- Sedentary lifestyle → lower energy demand.
- Reason: Muscles use more glucose + oxygen for respiration during movement.
2. Age
- Children & Teenagers: Higher energy per body mass for growth + development. Active lifestyles add extra demand.
- Adults: Energy stabilises → mainly for maintenance, repair, daily activity.
- Elderly: Lower energy needs → slower metabolism, less growth, reduced activity.
3. Pregnancy
- Pregnant women need extra energy for:
- Foetus growth.
- Development of placenta + amniotic fluid.
- Supporting increased body mass.
- Milk production (lactation).
- Also need more protein, iron, calcium in diet.
📊 Summary Table
| Factor | Energy Requirement | Why? |
|---|---|---|
| Activity Level | Higher in active people | Muscles need more respiration |
| Age | Children/teens → high Adults → moderate Elderly → lower | Growth, repair vs. maintenance vs. slower metabolism |
| Pregnancy | Higher | Foetus growth, placenta, milk production |
⚡ Quick Recap
Active → more energy (muscles need it).
Kids/teens → more (growth).
Elderly → less (slower metabolism).
Pregnancy → more (baby growth + milk).