Free OCR A Level Biology Adaptations Revision Notes

Module 4: Adaptations

These free OCR A Level Biology Adaptations revision notes have been written for specification point 4.2.2(g).

Adaptations are characteristics that improve an organism’s ability to survive and reproduce, such as:

There are three main categories of adaptation:

Anatomical adaptations are the structural features of an organism’s body.

Plant examples include:

Organism	Adaptation	Function
Marram grass	Long and/or deep roots	Stabilise dunes and absorb more water
Marram grass	Curled leaves	Reduce wind exposure
Marram grass	Hairy lower epidermis	Reduce airflow → trap moist air
Marram grass	Sunken and sunken stomata	Reduce air flow and water loss → reduce transpiration
Marram grass	Thick waxy cuticle	Prevent evaporation from leaf surfaces
Water lily	Stomata on the upper surface	Allow gas exchange while floating on water
Water lily	Air spaces in leaf tissues	Aid buoyancy and flotation
Water lily	Flexible leaf stalks	Allow movement with water currents

Animal examples include:

Organism	Adaptation	Function
Arctic fox	Small ears, thick fur	Reduce heat loss in cold climates
Camel	Wide calloused feet	Distribute surface area for walking on hot sand

Behavioural adaptations are actions or responses that improve survival or reproduction.

Plant examples include:

Organism	Behaviour	Purpose
Marram grass	Leaves roll up tighter when dry	Reduces surface area and conserves water
Marram grass	Close stomata when water is low	Limit water loss through transpiration
Marram grass	Grows upwards when buried	Reaches sunlight after sand deposition

Animal examples include:

Organism	Behaviour	Purpose
Earthworm	Retreats into a burrow when touched	Avoids predation
Swallow	Migrates in winter	Avoids cold and food shortages
Sea cucumber	Ejects guts and fluids when threatened	Startles predators/aids escape

Physiological adaptations involve internal processes or chemical changes.

Plant examples include:

Organism	Adaptation	Function
Marram grass	Low water potential in cells	Allows water uptake in salty or dry soils
Marram grass	Turgor changes roll/unroll leaf	Minimises water loss from transpiration

Animal examples include:

Organism	Adaptation	Function
Desert animals	Produce very concentrated urine	Conserve water
Antarctic fish	Produce antifreeze proteins	Prevent blood from freezing
Humans	Sweating	Thermoregulation