4- bioenergetics Flashcards
is photosynthesis endothermic or exothermic
endothermic becuase energy is transfered from environment in process
where does photosynthesis take place
in chloroplasts in green plant cells which contain pigments like chlorophyll that absorb light -energy is transferred to chloroplasts from environment by light
how does photosynthesis use energy
it uses energy to change carbon dioxide and water into glucose and oxygen
what is the word and symbol equation for photosynthesis
carbon dioxide + water —-(light)—-glucose+oxygen
symbol-
6C02 + 6H2O —(light)— C6H12O6 + 6O2
how do plants use glucose
1- respiration(transfers energy from glucose which enables plant to convert rest of glucose into other substances)
2- making cellulose- glucose converted into cellulose to make strong plant cell walls
3-making amino acids-glucose combined with nitrate ions (absorbed from soil) to make amino acids which is used to make proteins
4-stored as oils/fats= glucose turned into lipids for storing in seeds
5-stored as starch= glucose turned into starch, stored in roots,stems,leaves = ready for sue when photosynthesis isnt happening like winter
starch is insoluble =better for storing than glucose=cell with lots of glucose would draw in lots of water causing it to swell
limiting factors affecting the rate of photosynthesis
light
concentration of co2
temperature
when these factors become limiting, it stops photosynthesis from happening any faster
which factor is limiting at a particular time depends on environment conditions
-at night- light is limitiing
-winter-temperature is limiting
-if its warm+bright enough= co2 is limiting
chlorophyll can also be limiting factor = amount of chlorophyll can be affected by disease(e.g.tobacco mosaic virus)
environmental stress=lack of nutrients
causes chloroplasts to be damaged, not make enough chlorophyll
rate of photosynthesis is reduced as they cant absorb as much light
not enough light slows down the rate of photosynthesis- explain how this works
=light provides energy
light level raised=rate of photosynthesis increases
beyond that it wont make any difference
as light intensity increases, rate will no longer increase because it will be temp/ co2 level as limiting factor
in lab =light intensity can be changed by moving lamp closer or further away from plant
graph- light intensity at plant vs rate of photosynthesis
too little co2 slows down rate of photo synthesis =explain how this work
amount of co2 will only increase rate of photosynthesis up to a point, after this graph flattens out as amount of co2 increases= rate no longer increases showing co2 is no longer limiting factor
so if light and co2 are plentiful= limiting factor must be photosynthesis
too little co2 slows down rate of photo synthesis =explain how this work
amount of co2 will only increase rate of photosynthesis up to a point, after this graph flattens out as amount of co2 increases= rate no longer increases showing co2 is no longer limiting factor
so if light and co2 are plentiful= limiting factor must be photosynthesis
temperature has to be just right for photosynthesis=explain how this works
if it is too low= enzymes needed for photosynthesis work more slowly at low temperature
if plant gets too hot =enzymes needed for photosynthesis and other reactions will be damaged
- happens at about 45 degrees
how to find out what the limiting factor is between two factors
if there are 2 lines increase steadily and level off at the same place due to light intensity but one has temp of 15 and other has temp of 25= temp is limiting factor
if there are two lines with the temp of 25 degrees
but one has a co2 conc of 0.4 % and other with conc of 0.04% =limiting factor is at 0.04% CO2
explain the canadian pondweed practical
used to measure effect of light intensity on rate of photosynthesis=rate at which pondweed produces oxygen corresponds to the rate at which its photosynthesising=faster the rate of oxygen production=faster rate of photsynthesis
1- source of white light is placed at a specific distance from pondweed
2- pondweed is left to photosynthesis for a set amount of time, as it photosynthesises, oxygen released will collect in capillary tube
3-at end, syringe is used to draw gas bubble in tube alongside a ruler and the length of the gas bubble is measured= this is proportional to the volume of o2 produced
any variables affecting results should be controlled- temp & time pondweed is left to photosynthesise
experiment repeated twice with the light source at the same distance and the mean volume of o2 produced and calculated
whole experiment repeated at different distances and mean volume of o2 is produced and calculated
apparatus can be altered to measure effect of temp or co2 on photosynthesis(test tube of pondweed can be put into water bath at set temp/ measure amount of sodium hydrogencarbonate can be dissolved in water giving off co2)= experiment repeated at different temps of water/concentrations of sodium hydrogencarbonate
explain what the inverse square law is
light intensity is proportional to 1/distance^2
if you halve distance, light intensity will be 4x greater
if you third the distance, light intensity will be 9x greater
if you double distance, light intensity will be 4x smaller
triple to distance, 9x smaller
how can you artificially create the ideal conditions for farming
-greenhouse= traps the sun’s heat, makes sure temp does not become limiting
in winter, farmer might use heater to keep temp at ideal level
summer (too hot) shades and ventilations used to cool down
commercial farmers supply artificial light after sun goes down to give plants more photosynthesis time
increase levels of co2 with paraffin heater , as paraffin burns- co2 made as by product
keeping plants enclosed in greenhouse helpsprotect from pests and disease, farmer can add fertilisers to soil to provide minerals for healthy growth
important that everything is supplied in right amount or money would just be wasted
what is respiration
exothermic reaction transfers energy to environment =
process of transferring energy from breakdown of glucose which goes on in every cell of body continuosly
occurs in plants to,all living things respire=how they transfer energy from food
