bioenergetics Flashcards
where does photosynthesis take place and why
in the leaves as they contain the green chemica; chlorophyll, which absorb light energy
is photosynthesis endo or exo
endothermic, light is taken from environment
photosynthesis WORD EQUATION
carbon dioxide + water —> glucose + oxygen
photosynthesis SYMBOL EQUATION
6CO2 + 6H2O → C6H12O6 + 6O2
5 ways plants use glucose
- release energy via respiration
- making cellulose to strengthen cell
- combined with nitrate ions from soil to produce amino acids for protein synthesis
- stored as oils or fats as storage form of energy in seeds
- stored as insoluble starch to be converted back to glucose when needed
what is a limiting factor
if rate increases due to increase in factor, that factor was limiting, as it is stopping photosynthesis happening any faster
how can chlorophyll affect the rate of photosynthesis
patches of chlorophyll means less light can be absorbed, slowing rate
what happened to the rate of photosynthesis as light level rises
- increases as there is more energy to carry out the reaction, creating a faster rate
- stops increasing at certain point, temp or co2 is now limiting factor
describe rate of photosynthesis as co2 increases
- increases as there is more co2 to react
- stops increasing at certain point, something else is now limiting factor
what happens to the rate of photosynthesis as temperature changes
too low - enzymes work slowly
too hot - enzymes denature
how to find out what is the limiting factor
- increase level of another factor
- if rate of phtsynth increases, that factor was limiting
- if rate does not change, factor is no longer limiting factor, so increase another
how to investigate effect of light on photosynthesis
- place boiling tube 10cm away from led light source (led keeps temp stable)
- fill tube with sodium hydrogen carbonate solution (gives CO2 needed)
- put pondweed in tube
- attach capillary tube with gas syringe attached
- start timer
- after 1 min, use syringe to draw gas bubble alongside a ruler. this is proportional to volume of O2 produced
- repeat 2 more times at 10cm
- repeat whole experiment at 20cm, 30, 40, 50
issues of measuring co2 produced by pondweed by counting bubbles
- fast rate may be difficult to count
- bubbles are different sizes
what will co2 produced x distance graph show
inverse square law - when distance doubles, light intensity will be 4 times smaller meaning co2 produced will be 4 times smaller
how can limiting factors be useful
to increase yield in greenhouses:
- use heaters and ventilation to increase rate
- use glass roofs and artificial light to increase rate
- use paraffin heaters to release co2 to increase rate
issues of utilising limiting factor in greenhouses
expensive - expenses have to be justified by the increase in yield
is respiration endo or exo
exo, energy is released
uses of energy
- movement
- stabilise body temp
- for chemical reactions to build larger molecules eg proteins from amino acids
aerobic respiration word and symbol equation
glucose + gas –> co2 + water (+ energy)
C6H12O6 + O2 –> CO2 + H20
when is each type of respiration used
with oxygen: aerobic
not enough oxygen: anaerobic
aerobic vs anaerobic in terms of energy released
aerobic: a lot, as glucose is fully oxidised
anaerobic: much less, as oxidation of glucose is incomplete
word equation for anaerobic decay in muscles
glucose –> lactic acid (+energy)
word equation for anaerobic respiration in plant and yeast cells
glucose –> ethanol + co2 (+energy)
describe anaerobic respiration in yeast
fermentation - to make:
- alcoholic drinks: uses ethanol produced
- bread: uses co2 produced to make it bubble and rise
describe bodys response to exercise in oxygen conditions
- more energy demand for muscle contraction
- aerobic respiration increases to release more energy
- more oxygen demand for aerobic respiration
- breathing rate and volume increases to provide more oxygen
- heart rate increases to pump oxygenated blood around body
describe bodys response to vigorous exercise in not enough oxygen
- anaerobic respiration occurs
- incomplete oxidation of glucose leads to lactic acid build-up
- lactic acids causes fatigue in muscles, meaning they stop contracting efficiently
- blood transports lactic acid to liver, where chemical reactions convert it back to glucose
- rapid breathing will continue after exercise due to oxygen debt
what is oxygen debt
the amount of extra oxygen needed after exercise for energy to remove lactic acid
the is metabolism
sum of all the chemical reactions in a cell or in the body
glucose reactions in metabolism
in plants, glucose converted to:
- cellulose to strengthen cell wall
- starch to store glucose
- (+ nitrate ions) amino acids for protein synthesis
in humans, glucose converted to glycogen to store glucose
lipid reactions in metabolism
lipid synthesis: 1 molecule of glycerol + 3 fatty acids forms lipid molecule that is found in cell membrane
protein reactions in metabolism
excess is broken down to produce urea, which is excreted by kidneys
