Topic 3A - Exchange And Transport Systems Flashcards
How does an organisms size relate to their surface area to volume ratio
The larger the organisms, the lower the surface area to volume ratio
How does an organisms surface area to volume ratio relate to their metabolic rate
The smaller the surface area to volume ratio, the higher the metabolic rate
Name 3 features of an efficient gas exchange surface
Large surface area
Thin/short diffusion distance
Steep concentration gradient
Name and describe the three main features of an insects gas transport system
Spiracles - holes on the body surface which may be opened or closed by a valve for gas or water exchange
Trachea - large tubes extending through all body tissues, supported by rings to prevent collapse.
Tracheoles - smaller branches dividing off the tracheae
Explain the process of gas exchange in insects
Gases move in and out of the tracheae through spiracles
A diffusion gradient allows oxygen to diffuser into the body tissue while waste CO2 diffuses out
Contraction of muscles in the trachea allows mass movement of air in and out
Why cant fish use their bodies as an exchange surface
They have waterproof, impermeable outer membrane and a small surface area to volume ratio
Name and describe the two main features of a fishs gas transport system
Gills - there are multiple projections of gill filaments which are stacked up in piles.
Lamellae - give an increased surface area. Blood and water flow across them in opposite directions.
Explain the process of gas exchange in fish
The fish opens its mouth to enable water to flow in, then closes its mouth to increase pressure
The water passes over the lamellae, and the oxygen diffuses into the blood stream.
Waste carbon dioxide diffuses into the water and flows back out the gills.
How does the counter current system maximise oxygen absorbed by the fish
Maintains a steep concentration gradient, as water is always next to blood of a lower oxygen concentration. Keeps rate of diffusion constant an enables 80% of available oxygen to be absorbed.
Name and describe three adaptations of a leaf that allow efficient gas exchange
Thin and flat to provide short diffusion pathway and large surface area to volume ratio
Many small pores in the underside of the lead allowing gases to easily enter
Air spaces in the mesophyll allows gases to move around the leaf, facilitating photosynthesis
How do plants limit their water loss while still allowing gases to be exchanged
Stomata regulated by guard cells which allows them to open as close as needed
Most stay closed to prevent water loss while some open to let oxygen in
Explain the process of inspiration
Intercostal muscles contract, pulling the ribs up and out
Diaphragm contracts and flattens
Volume of the thorax increases
Air pressure outside lungs is higher than air pressure inside so air rushes in
Explain the process of expiration
Intercostal muscles relax, pulling the ribs down and in
Diaphragm relaxes and domes upwards
Volume of the thorax decreases
Air pressure outside lungs is lower than air pressure inside so air rushes out
What is tidal volume
The volume of air we breathe in and out during each breath at rest
What is breathing frequency
The number of breaths we take per minute
