CIE iGCSE Biology-18.2 Adaptive features- Study Notes- New Syllabus
CIE iGCSE Biology-18.2 Adaptive features- Study Notes – New syllabus
CIE iGCSE Biology-18.2 Adaptive features- Study Notes -CIE iGCSE Biology – per latest Syllabus.
Key Concepts:
Core
- Describe an adaptive feature as an inherited feature that helps an organism to survive and reproduce in its environment
- Interpret images or other information about a species to describe its adaptive features
Supplement
- Explain the adaptive features of hydrophytes and xerophytes to their environments
Adaptive Features – Inherited Traits That Support Survival
Definition:
An adaptive feature is an inherited characteristic that helps an organism to survive and reproduce in its natural environment.
These features develop over many generations through the process of natural selection.
🔍 Key Characteristics of Adaptive Features:
- They are genetic (passed from parent to offspring)
- They increase the chances of survival
- They help the organism to successfully reproduce
- They are shaped by the environment in which the organism lives
🧾 Examples of Adaptive Features:
| Organism | Adaptive Feature | How It Helps |
|---|---|---|
| Polar bear | Thick fur and a layer of body fat | Keeps warm in icy Arctic temperatures |
| Cactus | Spines and thick stem | Reduces water loss, stores water in deserts |
| Fish | Gills | Allows breathing under water |
| Camouflaged insect | Body colour matches surroundings | Avoids predators by blending in |
| Desert fox | Large ears | Releases excess body heat |
📌 Types of Adaptive Features:
- Structural adaptations – Physical traits (e.g. long neck in giraffes)
- Behavioural adaptations – Actions or behaviours (e.g. birds migrating)
- Physiological adaptations – Internal processes (e.g. snake venom production)
🧠 Why Are Adaptive Features Important?
Organisms with useful adaptations are more likely to survive, find food, escape predators, and pass on their genes to the next generation.
Over time, these features become common in the species.
Organisms with useful adaptations are more likely to survive, find food, escape predators, and pass on their genes to the next generation.
Over time, these features become common in the species.
Interpreting Adaptive Features from Images or Information
🔍 How to Interpret Adaptive Features:
- Observe the structure or trait carefully → What does the organism have that stands out?
- Link the feature to its function → What purpose might this feature serve?
- Connect it to the environment → How does this feature help the organism survive in its habitat?
🧾 Example 1: Camel in the Desert
| Feature from Image or Info | Adaptive Function |
|---|---|
| Long eyelashes | Protect eyes from blowing sand |
| Hump on the back | Stores fat for energy and water |
| Wide, flat feet | Prevent sinking into sand |
| Thick fur on top, thin underneath | Insulates against daytime heat and cold nights |
🧾 Example 2: Arctic Fox 
| Feature | Adaptive Advantage |
|---|---|
| White fur | Camouflage in snow |
| Small ears and short nose | Reduces heat loss |
| Thick fur and fat layer | Provides insulation in freezing climate |
🧾 Example 3: Cactus
| Feature | Adaptive Benefit |
|---|---|
| Spines instead of leaves | Reduces water loss and deters herbivores |
| Thick, fleshy stem | Stores water during drought |
| Shallow, wide roots | Quickly absorb surface water after rain |
🧠 Key Tip:
Always connect the visible or described feature to how it helps the organism survive and reproduce in its environment.
This is the best way to describe adaptive features clearly and correctly.
Always connect the visible or described feature to how it helps the organism survive and reproduce in its environment.
This is the best way to describe adaptive features clearly and correctly.
Adaptive Features of Hydrophytes and Xerophytes
What Are Hydrophytes and Xerophytes?
| Type | Description |
|---|---|
| Hydrophytes | Plants adapted to live in water or very wet areas (e.g. water lilies, lotus) |
| Xerophytes | Plants adapted to survive in dry conditions, like deserts (e.g. cacti, aloe) |
💧 Hydrophytes – Adapted to Wet Conditions
| Feature | Function / Benefit |
|---|---|
| Large air spaces in stems/leaves | Help the plant float and store oxygen |
| Stomata on upper leaf surface | Allows gas exchange above water |
| Thin or no cuticle | No need to reduce water loss in a water-rich environment |
| Flexible stems and leaves | Prevents breakage by flowing water |
| Flat, broad leaves | Increase surface area for photosynthesis at water surface |
🧪 Example: Water lily – floats on water, broad leaves, stomata on top
🔥 Xerophytes – Adapted to Dry Conditions
| Feature | Function / Benefit |
|---|---|
| Thick waxy cuticle | Reduces water loss by evaporation |
| Small or rolled leaves | Reduces surface area and traps moisture |
| Sunken stomata | Create humid pockets to reduce water loss |
| Stomata open at night (CAM) | Prevents water loss during hot daytime (common in cacti) |
| Deep or widespread roots | Absorb water from deep underground or large area |
| Fleshy stems | Store water for dry periods |
🧪 Example: Cactus – thick stems, spines instead of leaves, stores water
🧠 Summary Table:
| Feature Type | Hydrophytes (Water Plants) | Xerophytes (Desert Plants) |
|---|---|---|
| Environment | Wet / aquatic | Hot, dry / arid |
| Leaf adaptation | Large, floating leaves | Small, rolled, or spiny leaves |
| Stomata location | On upper leaf surface | Sunken or fewer stomata, open at night |
| Cuticle thickness | Thin or absent | Thick waxy cuticle |
| Water conservation | Not needed | Highly efficient adaptations to reduce loss |
| Example | Water lily, lotus | Cactus, aloe vera |