BRAINCAKEExchange of Gases
Revision notes for Exchange of Gases in AQA Biology (7401). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.
- Tissue FluidThe internal environment of multicellular organisms is called tissue fluid.
- The Need for Specialised Exchange SurfacesOxygen, glucose and fatty acids are needed for respiration and carbon dioxide needs to be removed.
- Surface Area to Volume RatioExchange of substances with the environment takes place at the surface of an organism, but the materials absorbed are used throughout the whole…
- The Rate of DiffusionThe rate of diffusion is proportional to the surface area and the concentration gradient and is inversely proportional to the length of the…
- Features of A Specialised Exchange SurfaceExchange Surfaces: should have a large surface area relative to the volume of the organism should be very thin so that the diffusion distance is…
- Gas Exchange in Unicellular OrganismsSingle-celled organisms have a large surface area to volume ratio because they are small.
- Gas Exchange in InsectsThe need for gas exchange conflicts with the need to conserve water.
- Diffusion GradientFor rapid diffusion to take place, there has to be a steep diffusion gradient maintained in one direction.
- Mass TransportMost tracheoles extend parallel to the muscle fibres.
- Increasing the Rate of DiffusionTracheoles are the small tubes that form the terminal endings of the tracheal system and range from 1 to 0.1 μm in diameter.
- Limitations of the Tracheal SystemReducing Water Loss Gases enter and leave through tiny pores called spiracles.
- Gas Exchange in FishAll gas exchange systems must supply oxygen to respiring tissues and remove carbon dioxide produced by respiration rapidly enough.
- Structure of the GillsFish have a waterproof covering.
- Counter Current ExchangeThe gill lamellae have a rich blood supply.
- Gas Exchange in LeavesThe gas exchange system of each species depends on environmental conditions, size, movement and energy consumption.
- StomataGases enter the leaf through pores called stomata.
- Limiting Water Loss in InsectsIn terrestrial organisms, gas exchange systems are exposed to the environment.
- Limiting Water Loss in PlantsPlants need a large surface area to volume ratio to maximise photosynthesis and to capture as much light as possible.
- The Human Gas Exchange SystemHumans like other mammals are aerobic organisms that need a constant supply of oxygen and need carbon dioxide constantly removed from the body as…
- The LungsThe lungs are a pair of structures made up of branched tubules called bronchioles which end in tiny air sacs called alveoli The trachea is a…
- Mechanism of BreathingVentilating the lungs maintains the diffusion gradient across the alveolar epithelium by refreshing the air inside the alveoli.
- InspirationInspiration is an active process that uses energy.
- ExpirationExpiration is a largely passive process that does not require much energy.
- AlveoliAlveoli are the specialised gas exchange surface in the lungs.
- Role of Alveoli in Gas ExchangeThe rate of diffusion is proportional to the surface area and the diffusion gradient and inversely proportional to the diffusion distance.
- Correlation and CausationCorrelation occurs between two variables when a change in one of the variables is reflected by a change in another variable.
- Risk Factors for Lung DiseaseRisk is the probability of getting a disease.
- Smoking and Lung CancerSmoking lowers an individual's life expectancy as it damages the heart and lungs and other organs.
On the specification
- 3.3.1 Surface area to volume ratio
- 3.3.2 Gas exchange