Large animals have a small surface area to volume ratio. Large animals also lose heat slowly which is good in cold climates meaning they need to eat less.
1 of 15
Surface area to volume ratio in small organisms
Small organisms have a large surface area to volume ratio
Small organisms lose heat energy quickly
Small organisms need lots of food as they lose heat energy quickly
2 of 15
Gas exchange in fish
Use gills to absorb oxygen
Carbon dioxide leaves by the gills through diffusion.
Each gill has filaments folded into lamellae
Which increases surface area
Blood capillaries circulate round the gills
3 of 15
Ventilation in fish
Water moves over the gills of fish
Oxygenated water always moves over fishes gills
Blood flows in the opposite direction it is a counter current.
4 of 15
Gas exchange in insects
Open circulatory system
Tracheal system with branches that hold fluid filled sacs.
Which allow gas exchange.
5 of 15
Ventilation in insects
When they move their body is able to pump air in
Change in thorax increases pressure allowing air in and out
6 of 15
Exchange in plants
Gas exchange via stomata open to allow carbon dioxide to diffuse out.
And an easy way for water to escape
Transpiration is the loss of water by evaporation
7 of 15
Adaptations of plants
Xerophytes: have small leaves to reduce surface area and for less water loss by transpiration
Dense spongy mesophyll meaning less water to evaporate and less cell surface area exposure.
Thick waxy cuticle which reduces evaporation
Pits contain stomata at the base and trap air
Rolled leaves Trap air and eliminate water gradient
Low water potential in leaves by having high salt concentrations in plant
8 of 15
Gas exchange in humans
Airways
Flexible and able to stretch and recoil.
Withstand high and low pressure
Divide into small airways
9 of 15
Human gas exchange lungs
Air passes through trachea, bronchi and bronchioles
Air reaches alveoli
lungs protected by ribs
movement of ribs and lungs by ventilation
10 of 15
Human gas exchange Trachea and bronchi
Bronchi narrower than trachea
Walls of cartillage in c shaped rings called epithelium
11 of 15
Human gas exchange Bronchioles
Narrower than bronchi
smooth muscle and elastic fibres
small clusters of alveoli at the end
12 of 15
Gas exchange in humans alveolar epithelium
2 cells thick
short diffusion pathway
Diffusion of carbon dioxide and oxygen
13 of 15
Inspiration
Ribcage moves up and out
Diaphragm contracts
Volume increases
pressure decreases
Pressure greater outside of the body forcing air in
Comments
No comments have yet been made