respiration and gas exchange 2.34, 2.35, 2.36, 2.37, 2.38, 2.39, 2.40B, 2.41B, 2.42B, 2.43B, 2.44B, 2.45B Flashcards
what is aerobic respiration?
use of oxygen to break down glucose and release energy
some energy is released as heat but most is trapped as a useable form of ATP
what is the word equation for aerobic respiration?
glucose + oxygen > carbon dioxide + water
what is the symbol equation for aerobic respiration?
C6H12O6 + 6O2 > 6CO2 + 6H2O
why does aerobic respiration release a lot of ATP?
because it completely oxidises the glucose
examples of uses of energy:
cell division
contracting muscle cells
building large molecules
transporting molecule
maintaining body temperature
when is photosynthesis faster than respiration in plants?
durning the day, at higher light intensities - there is a net uptake of carbon dioxide and net release of oxygen
oxygen is excreted from the leaves
when is respiration faster than photosynthesis?
in the dark, at low light intensities - there would be a net uptake of oxygen and a net release of carbon dioxide
carbon dioxide is excreted from the leaves
where does gas exchange occur?
in the airspaces in the leaves and atmosphere
oxygen and carbon dioxide diffuse through the stomata
how are guard cells specialised for gas exchange?
the guard cells form the stomata which change shape altering its size
how are stomatas specialised for gas exchange?
they close to reduce water loss (and gas exchange) this is when the plant has lost too much water so stomatas turn flaccid
allows gases to diffuse in and out the air spaces in the leaf, providing short diffusion distance to mesophyll cells
whats the symbol equation for respiration in plants?
C6H12O6 + 6O2 > 6CO2 + 6H2O
what is cell respiration?
the process of breaking down food molecules. to release ATP
what’s anaerobic respiration?
respiration without oxygen
glucose is not completely broken down so less ATP and energy is released
produces toxic waste products, which must be excreted or broken down
advantage allows cells to obtain small amount of usable energy when oxygen is limited
what does anaerobic respiration in fungi and plants produce?
glucose > ethanol + carbon dioxide
very useful in food production
we use yeast in bread and alcohol production
-co2 forms bubbles in bread dough, causing it to rise
-ethanol provides alcohol content
what does anaerobic respiration in animals produce?
glucose > lactic acid
what happens when our muscles anaerobically respire?
occurs in muscle cells when shortage of oxygen
-muscles require large quantities of energy, more than provided by aerobic respiration
-glycogen stored in muscle cells is broken down into glucose
-lactic acid builds up causing cramps and diffuses into blood
-high concentration is toxic so transported to liver where it is oxidised
what is it called when volume of oxygen needed to oxides lactic acid?
oxygen debt
practical: investigating evolution of carbon dioxide and heat from respiring seeds or other suitable living organisms - germinating peas
want to show that only living things respire - control experiment
thermo flasks, dead and alive pea seeds (soaked in Milton solution - preservative and kills bacteria, that would respire affecting results), thermometers
as peas grow they start to respire, releasing heat
thermo flask insulated, heat not transferred to surroundings and we can measure change in temp
only see change in temp of alive peas
use gas delivery tubes to collect gas, gas bubbled through limewater, alive peas gas turn cloudy as co2 is released
practical: investigating evolution of carbon dioxide and heat from respiring seeds or other suitable living organisms - hydrogen carbonate indicator and insects
want to show that only living things respire - control experiment
test tubes, insect, support, hydrogen carbonate indicator
yellow: respiration>photosynthesis
CO2>O2
orange: repiration=photosnythesis
CO2=O2
pink: respiration<photosynthesis
CO2<O2
practical: investigating anaerobic respiration in yeast
delivery tube, limewater, test tube/boiling tubes, thin layer of oil, glucose and yeast suspension
used to investigate the effect of changing a single variable on the rate of anaerobic respiration of yeast
dependent variable is time taken for limewater to become cloudy
or measure volume of carbon dioxide produced
what’s the symbol equation for plants photosynthesising?
6co2 + 6h2o > c6h12o6 + 6o2
how to the leaf specialised for gas exchange?
thin so diffusion distance is short
large surface area increasing number of stomata, CO2 diffuse quicker
maximises light absorption
list the structure of a leaf from the top, downwards:
cuticle
upper epidermis
palisade cells and mesophyll
xylem and phloem
spongy mesophyll
lower epidermis
stomata and guard cells
how is the upper epidermis specialised for photosynthesis?
transparent so light can penetrate the mesophyll
how are the palisade cells specialised for photosynthesis?
long, thin and tightly packed
contain large amounts of chloroplasts, maximising the absorption of sunlight energy
palisade mesophyll is the main site of photosynthesis
