S4 - Respiration and Gas Exchange Flashcards
respiration:
-respiration occurs in every cell in the body if all livings things to supply ATP (adenosine triosphate) to cells
-cellular respiration is an exothermic reaction
-there are 2 types of respiration: aerobic and anaerobic
aerobic respiration:
-this uses oxygen
-it yields the most energy
-most of the reactions that make up aerobic respiration occur in the mitochondria
glucose + oxygen -> carbon dioxide + water
C6H12O6 + O2 -> CO2 + H2O
balanced C6H12O6 + 6O2 -> 6CO2 + 6H2O
anaerobic respiration:
-occurs when there is not enough oxygen
-it does not yield as much energy as aerobic respiration
-it is only used as a last resort, for example during a sprint where it is difficult to breathe in enough oxygen
-the oxidation of glucose in complete
in animals:
glucose (C6H12O6) -> lactic acid
in plant and yeast cells it is (called fermentation):
-glucose (C6H12O6) -> ethanol (C2H6O) + carbon dioxide (CO2)
-this reaction is used to make bread and alcoholic drinks
practical: investigate the evolution of carbon dioxide from respiring seeds or other suitable living organisms
1) connect a capillary tube from the air into a flask containing sodium hydroxide, which will absorb carbon dioxide
2) connect this flask with a capillary tube to another flask containing hydrogen carbonate indicator (which is red at neutral pH and yellow at low pH, i.e. when carbon dioxide is present)
3) connect the second flask to a third flask containing either germinating seeds or respiring animals, such as worms
4) connect the third flask to another flask containing hydrogen carbonate indicator, such as in step 2
results: the sodium hydroxide solution in the first flask will absorb carbon dioxide from the air, which will turn the second flask red, as it will have a neutral pH. However, the respiring organism will produce carbon dioxide and will therefore turn the indicator yellow
practical: investigate the evolution of heat from respiring seeds or other suitable living organisms
1) use 2 vacuum flasks, one containing living germinating seeds and the other containing dead or boiled seeds (as a control)
2) put a thermometer wrapped in cotton wool (to prevent heat from escaping) to measure temperature
3) measure initial temperature
4) leave seeds for a few days and then measure end temperature
-the live germinating seeds will release heat due to aerobic respiration and so the temperature will increase
structure of thorax:
-ribs: bone ‘cage’ surrounding the lungs to provide protection of internal organs
-intercostal muscle: muscles found between the ribs that control inhalation and exhalation
-diaphragm: muscular dome at the bottom of the thorax that changes the pressure in order to control inhalation and exhalation
-trachea: the windpipe, where air enters the thorax and flows to the lungs
-bronchi: the trachea divides into 2 bronchi-one to each lung
-bronchioles: the bronchi further divide into smaller tubes that connect to the alveoli
-alveoli: tiny air sacs that are the place of gas exchange
-pleural membrames: found on the outside of the lungs and inside of chest cavity to lubricate the lungs-reducing friction when breathing
intercostal muscles and diaphragm in ventilation:
-intercostal muscles: inhalation -> contract, exhalation -> relax
-ribcage: inhalation -> up and out, exhalation -> down and in
-diaphragm: inhalation -> contracts downwards, exhalation -> relaxes upwards
-pressure: inhalation -> decreases, exhalation -> increases
-air movement: inhalation -> moves in, exhalation -> moves out
-air moves from areas of high pressure to low pressure, so when the thorax pressure decreases (as a result of increased volume created by the intercostal muscles moving the ribcage up and out and the diaphragm flattening) air moves from the higher pressure air down into the lower pressure thorax
alveoli adaptations:
-thin cell walls: one cell thick so there is a shorter distance of diffusion
-folded: to increase surface area for diffusion
-large network of tiny capillaries: increases concentration gradient between air in alveoli and the blood, as oxygen can move away in the blood and carbon dioxide can be breathed out
consequences of smoking:
-damages the walls inside the alveoli, reducing the surface area for gas exchange and leading to diseases like emphysema
-the tar in the cigarettes damages the cilia in you lungs and trachea making chest infections more likely
-tar also irritates the bronchi and bronchioles, encouraging mucus to be produced which can’t be cleared well by damaged cilia-this causes smoker’s cough and chronic bronchitis
-the carbon monoxide in cigarette smoke reduces the amount of oxygen the blood can carry, to make up for this, heart rate increases-which lead to an increase in blood pressure, high blood pressure damages the artery walls, making the formation of blood clots more likely which increases the risk of coronary heart disease (e.g. heart attacks)
-tobbaco also contains carcinogens-chemical that can lead to cancer
practical: investigating the effect of exercise on breathing rate
1) sit for five minutes
2) for one minute, count the number of breaths you take
3) do four minutes of exercise and as soon as you stop count your breaths for a minute
4) repeat the steps above, and work out the average results for resting and after exercise
5) you could also pester two other people to do the same so you get three sets of results to compare
results: your results show that exercise increases breathing rate, this is because you muscle respire more during exercise. They need to be supplied with more O2 and have more CO2 removed, so your breathing rate increases
-in this experiment you need to control the time exercising, and the temperature
practical: investigating the effect of release of carbon dioxide in your breath
1) set up 2 boiling tubes and put the same amount of limewater in each
2) put your mouth around the mouthpiece and breathe in and out several times
3) as you breathe in, air from the room is drawn in through boiling tube A. This air contains very little carbon dioxide so the limewater in this boiling tube remains colourless
4) when you breathe out, the air you exhale bubbles through the limewater in boiling tube B. This air contains CO2 produced during respiration, so the limewater in this boiling tube turns cloudy
results: since the limewater in tube A remains clear, you can tell the carbon dioxide in the exhaled air was from respiration-it wasn’t inhaled through boiling tube A. if you’d inhaled in the carbon dioxide, the limewater in boiling tube A would’ve turned out cloudy too
