15/02/2024

• Aerobic Respiration

  • Word equation: Glucose + oxygen -> carbon dioxide + water (+ATP)
  • Chemical equation: C6H12O6 + 6O2 -> 6CO2 + 6H2O (+ATP)
• Anaerobic respiration

  • Humans word equation: glucose -> lactic acid
  • Yeast: glucose -> carbon dioxide + ethanol
• State the function of the following in the respiratory system

  • Ribs: protect lungs
  • Intercostal muscles: found between each rib -> help to move ribcage up/out/down and in to increase/decrease volume chest cavity
  • Diaphragm: dome shaped muscle separate thorax from abolement -> help change the volume of thorax
  • Bronchus/bronchioles: complete rings of cartilage - keep airways open -> ciliated cells lining
  • Trachea: 'c' shapes cartilage -> support airways & keep open
• Diagram labelled:

  It is not rib muscles it is the intercostal muscles

  
• ATP's role

  • Transfers energy between process that release it (respiration) and processes that use it up -> e.g. muscle contraction
• Alveoli and key adaptations:

  • alveoli folded -> increased surface area for gaseous exchange
  • short diffusion distance -> thin membrane
  • many capillaries/rich blood supply -> maintain concentration gradient _> carries oxygen away
  • moist - gases diffuse more easily

  
• Effects of smoking

  Emphysema:

  • Walls of alveoli break down and parts of alveoli stick together, leading to decreased surface area for gas exchange
• Effects of smoking

  Carbon monoxide:

  • Binds to haemoglobin instead of oxygen, forming carboxyhaemoglobin, which results in less oxygen reaching respiring cells
• Effects of smoking

  Effect of tar:

  • Increases the risk of cancer due to carcinogens
  • Paralyses cilia, preventing them from sweeping away mucus
  • Acts as an irritant, causing an increased production of mucus
• Effects of smoking

  Bronchitis:

  • Inflammation of the bronchus caused by smoke
  • Accumulation of mucus due to damaged cilia
• Effects of smoking

  Smokers cough to try to remove mucus
• Effects of smoking

  Cancer:

  • Cigarettes contain carcinogens, leading to an increased risk of mutations
  • Mutations can result in uncontrollable division of cells, which can block the airway
• Effects of smoking

  Cilia:

  • Tar destroys cilia, paralysing them and preventing the sweeping away of mucus with trapped pathogens
• Compare aerobic and anaerobic respiration:

  Aerobic:

  • Oxygen
  • Carbon dioxide + water released
  • No oxygen debt lots ATP released complete breakdown glucose

  Anaerobic:

  • No oxygen
  • Lactic acid released
  • Oxygen debt
  • Some ATP released partially breakdown glucose

  They both use glucose
• Define respiration:

  Breakdown of food molecules (glucose) to release stored chemical energy they contain (in form ATP) (chemical process)

  Define breathing:

  Process of exchanging gases - inhalation / exhalation (physical process)
• Explain how cilia prevent lung infections

  • Goblet cells between ciliated cells secrete mucus -> traps pathogens -> prevent entering lungs and getting sick

  
• Advantages and disadvantages of anaerobic respiration

  Advantages:

  • Can occur when oxygen in short supply to release some energy

  Disadvantages:

  • Gives less energy
  • Causes cramp - build up lactic acid
  • Results in oxygen debt - volume oxygen needed to oxidise lactic acid
• Define diffusion:

  • NET movement of particles from an area of higher to lower concentration (No ATP required)

  Factors to speed up diffusion:

  • Temperature increases, meaning there will be an increase in kinetic energy
  • Concentration gradient
  • Distance (ie thin)
  • Surface area
• Results from the cube experiment:

  Smallest cube had largest SA:Vol ratio so fastest rate of diffusion went colourless first quickest.

  Largest cube ha smallest SA:Vol ratio so went colourless slowest -> like large / multicellular organism, demands can't be met by diffusion alone

  
• Germinating peas practical:

  • Peas not in boiled water, will be living and therefore respiring, respiration releases heat which can be measured using thermometer
  • Boiled peas are dead so won't respire so no increase in temperature
  • In flask to minimise heat loss to surrounding
  • Inverted to allow air in/out (Co2 toxic)

  
• Mealworm practical:

  • No insects, no respiration s hydrogen carbonate indicator remains cherry red -> at atmospheric levels
  • The other tube's indicator goes yellow

  
• Tests for exhaled air:

  • Test presence CO2 - limewater if true then it will turn cloudy
  • Hydrogen carbonate indicator -> increased concentration of CO2 - goes yellow
• Inhalation:

  Intercostal muscles - contract

  Ribs - up & out

  Diaphragm - contact and down/flatten

  Chest - volume increases

  Air pressure - pressure decreases

  Air movement - drawn in
• Exhalation:

  Intercostal muscles - relax

  Ribs - down & in

  Diaphragm - relax & dome shape

  Chest - volume decreases

  Air pressure - pressure increases

  Air movement - forced out
• Exercise practical

  IV: Intensity of exercise

  DV: Breathing rate

  CV: Same type of exercise, the same person should be doing the exercise

  Reliable: repeat & calculate the mean

  Accurate: Improving measurement technique - using an app that can detect breathing rate etc.
• Effect of exercise

  Short term:

  • Increased breathing rate
  • Increased tidal volume

  Long term:

  • Stronger diaphragm
  • Increased number of alveoli
  • Increased vital capacity
  • More efficient removal of CO2
  • Faster recovery after exercise