Topic 3A - Exchange and Transport Systems Flashcards
Give two thing that all gas exchange surfaces have in common.
Any two from:
Steep concentration gradient maintained across it
Short diffusion path
Large surface area
Explain why single celled organisms don’t need a gas exchange system.
They can exchange gases directly through their cell surface membrane. This has large surface area and short diffusion pathway
Describe the structure of fish gills.
Each gill is made of lots of thin plates called gill filaments. These are coveted in lots of tiny structures called lamellae. Lamellae have a thin surface layer of cells and a good blood supply.
Describe how the counter current system in fish aids gas exchange.
The counter current system works by maintaining a steep concentration gradient between the water and the blood along the length of the gill. Blood flows through the lamellae in one direction and water over them in the other. The water with high oxygen diffuses into the blood with low oxygen.
What is the main gas exchange surface for a dicotyledonous plant?
The surface of the mesophyll cells in the leaf.
Where do gases move in and out of a leaf?
Through the stomata in the epidermis
How does air get into an insect’s trachea?
Through the spiracles on the surface of the insect’s body
Describe how carbon dioxide moves out of an insect’s cells into the atmosphere.
Carbon dioxide from the cells move down its concentration gradient through the tracheoles towards the spiracles to be released into the atmosphere.
What is a xerophyte?
A plant specifically adapted for life in a warm, dry or windy habitat
Give three adaptations that xerophytic have have to reduce water loss
Any three from: Stomata sunk in pits Curled leaves with stomata inside A layer of hairs on the epidermis Reduced number of stomata Waxy, waterproof cuticles on leaves and stems
What is forced vital capacity (FVC)?
The maximum volume of air it is possible to breathe forcefully out of the lungs after a really deep breath in
A person with fibrosis scar tissue has a reduced tidal volume. Explain why.
Scar tissue is thicker and less elastic than normal lung tissue. This means the lungs are less able to expand and so can’t hold as much air as normal, so tidal volume is reduced
Explain why the rate of gaseous exchange in someone with fibrosis is slower than in a healthy person
Scar tissue is thicker than normal lung tissue so diffusion of gases is slower
What happens to FEV1 during an asthma attack?
Reduced air flow means that FEV1 is severely reduced (i.e less air can be breathed out in one second)
