4 - Respiration and Gas Exchange Flashcards
What is respiration?
The process of releasing energy from glucose which happens constantly in every living cell
Energy is released as chemical energy and heat
What is aerobic respiration?
Respiration when there is oxygen available
Glucose + oxygen —> carbon dioxide + water (+ energy)
C6H12O6 + 6O2 —> 6CO2 + 6H2O
What is anaerobic respiration?
Respiration without oxygen
Not the best way to respire as not as much energy is made
Happens during vigorous exercise
Glucose —> lactic acid (+ energy)
The lactic acid can lead to muscle cramps in the body
What is anaerobic respiration in plants?
When plants respire without oxygen
Glucose —> ethanol + carbon dioxide (+ energy)
Describe an experiment to detect the carbon dioxide produced in respiration
- Soak dried beans in water for a day so they begin to germinate (they will respire)
- Boil a similar sized second batch of dried beans
- This kills the beans so they cannot respire (the control)
- Put hydrogen-carbonate indicator into two test tubes
- Place a gauze platform into each test tube to put the beans on
- Seal with a rubber bung
- Leave for an hour
- The CO2 produced will then the indicator from orange to yellow
Describe an experiment to show the heat produced by respiration
- Prepare two sets of beans (one dried and one boiled)
- Add each set to a vacuum flask with a little air at the too (so they respire anaerobically)
- Put a thermometer into each flask and deal with cotton wool
- Record the temperatures daily for a week
- The beans are well-insulated in the flasks so when the germinating seeds respire the flask’s temperature will Rose
How do plants exchange gas?
By diffusion from the environment into the leaf
What does the net exchange of has depend on?
Light intensity
- Plants photosynthesise in light so diffuse CO2 and O2 in and out constantly
- At night there is no photosynthesis so the plant does not release oxygen (it is only taken in) and release only carbon dioxide
How are leaves adapted for gas exchange?
- Broad so large surface area for diffusion
- Thin so less distance to travel
- Air spaces to let CO2 and O2 move easily between cells as well as increasing the surface area for has exchange
- Stomata allow CO2 and O2 diffuse in and out and let’s water escape
- Stomata close at dark so no water is lost
- Stomata will close when there is little water left in the roots (stops the plant from photosynthesising but keeps it alive)
- The opening and closing of stomata are controlled by the guard cells
What does hydrogen-carbonate show?
- Carbon dioxide concentration
- Orange = normal concentration
- Yellow = increased concentration
- Purple = decreased concentration
Describe an experiment to show the difference in net gas exchange in plants
- Add the same volume of hydrogen-carbonate indicator to four boiling tubes
- Put similar leaves into three tubes and seal with a rubber bung (to stop it falling into the solution)
- Wrap one tube in aluminium foil and a second in gauze
- Put all the tubes in bright light
- Leave for an hour
- Tin foil = yellow as respiration took place but no photosynthesis
- Gauze = orange little photosynthesis and little respiration
- Uncovered = purple as lots of photosynthesis using carbon dioxide up
What is the thorax?
The top part of the body separated from the lower part by the diaphragm
Lungs
- Pink like sponges
- Protected by the ribcage
- Surrounded by the pleural membranes
Bronchi
- Air breathed in goes through the trachea to the two tubes of bronchi
- Bronchi split into bronchioles
- Bronchioles end at alveoli where gas exchange takes place
Where does gas exchange take place in humans?
The alveoli
