BRAINCAKEExchange of Gases
Revision notes for Exchange of Gases in AQA Biology (7401). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- 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 individuals life expectancy as it damages the heart and lungs and other organs.