Unit 3 SA:V + Gas Exchange Flashcards
What is an effective SA:V for exchange
Large (surface area compared to volume)
How does SA change with organism size?
As organisms get larger the SA:V gets smaller
Why do organisms exchange CO2 and O2?
O2 is used in aerobic respiration and CO2 is a product of aerobic respiration
How do single cells organisms conduct exchange and why?
Via simple diffusion as they have a large enough SA:V fir diffusion to supply their needs
What do larger organisms rely on for exchange and why?
Specialised exchange systems as they have too small an SA:V to rely on simple diffusion
Why do small mammals lose heat more rapidly than large mammals?
How do they combat this?
They have a larger SA:V allowing more rapid loss of heat
They have a higher metabolic rate (breath faster and higher heart rate) to provide more heat
What is Ficks law and what does it suggest about exchange surfaces?
Diffusion rate is proportional to SA x difference in conc over diffusion distance
This suggests effective exchange surface has a high SA, large conc grad and short diffusion distance
How do insects limit water loss
Large waterproof covering (exoskeleton covered in waterproof cuticle)
Small SA:V
How does oxygen move through an insect? (3 marks) and CO2?
- Oxygen enters through spiracles and into trachea(down conc gradient) spiracles close
2.diffuses from trachea to tracheoles down conc gradient
- Diffuses into tissues for aerobic respiration
CO2 is the same process in reverse
How are concentration gradients created in insects
Tissues aerobically respire - using up oxygen and producing CO2
Abdominal pumping movement ventilates by creating mass movement of fresh air, maintaining conc gradient
What are spiracles?
Tiny pores in insects that can be opened and closed to facilitate gas exchange and conserve water
What are trachea? (Insects)
A network of tubes supported by strengthened chitin rings, provide pathways for gaseous exchange
What are tracheoles? (Insects) and how are they adapted for gaseous exchange ?
Tubes which split off of the trachea and extend throughout the body, they are small, narrow and branched and there are many of them. Providing a large surface area for diffusion.
How are short diffusion distances maintained in insects?
Each cell is only a very short distance from a trachea or tracheole
How does water move in and out of the mouth and gills (fish)? (4 points)
Water moves in through mouth, out through gills
- Mouth opens, increasing volume and decreasing pressure inside mouth
- Water moves into mouth down pressure gradient
- Mouth shuts, decreasing volume, increasing pressure inside mouth
- Water forced over gills (down pressure gradient
How do the gills provide a large surface area?
Each fill has many gill filaments, each fill filament has many lamellae (at right angles to filaments) providing a very large surface area
