B8- Photosynthesis Flashcards
What do plants use as there source of energy ?
Light from the sun .
What is the reaction plants use to trap this light energy ?
Photosynthesis .
-Photosynthesis takes in energy , so it is an exmple of a n endothermic reaction .
Where does photosynthesis tke place ?
Photosynthesis takes place in the leaves of a plant . (palisade mesophyl)
-Leaves contain the green chemical chloropyll , chlorophyll can baosrb light energy .
What is the firsts tage of photosynthesis .
Carbondixoide is taken up by the plant into the leaf .
- Light energy is then absorbed by the chlorophyll .
- Ther energy is then used to convert co2 and water into the sgar glucose , this reaction also producs oxygen .
Write the symbol and word equation for photosynthesis .
Check sheet.
Check photosyntheis sheet, first graph , what does the first star show ?
When the light intensity is zero , the rate of photosyntheis sis zero . Plants need light to carry out photosynthesis
Check photosyntheis sheet, first graph , what does the second star show ?
- As we increase the light intensity , the rate of photosynthesis increases
- As the plnat has more light energy to carry out photosyntheisis reaction , so the reaction geets faster .
If we increase the liggt intensity and the rat eof photosynteiss increases , what does that show ?
It shows that light intensity is the LIMTING FACTOR ,. (pHontosytheiss was not as fast because there was not enough light ) .
Check photosyntheis sheet, first graph , what does the third star show .
- If we keep increasung the light intesnity , there come sup a point where he rate of phtoosyntehsis no longer increases .
- At this point light intensity is no longer the limiting factor . Something else is in short supply - co2 in the air .
Check photosynthesis sheet second graph , what does this show .
- As we increase the carbondixoide leve , the rate of photosyntheiss increases .
- This tells us co2 is the limtiing factor.
Check phtosynthesis sheet second graph . what does the first star show .
At a certain point , the rateof photosyntehsis no longer increases . Co2 is no longer a limtiing factor .
What is another think that affects the rate of photosyntheis s.
The amount of chlorphyll in the leaf , the less chlorophyl a leaf has (less green) , it can trapp less liht energy than leaves with more chorphyll , lowering the rate of photosyntheis .
Check last graph on photosynthesis shseet , what does the first star show .
Temperature also affectsthe rate of photosyntehsis .
As we increase the temperature , the enzymes involved in phtoosyntehsis work faster so rtae increases .
Check last graph on photosynthesis sheet , what does tthe second star show ?
-If we keep icnreasing the temperature , the enzymes will denature and the rate of photosyntheis falls .
What does th limting factors start one graph oone show ?
- Initially the rtae of photosyntheies increases as we increase lihgt intensity .
- This tells us light intensity is the ilmint factor at this point .
What odes limting factors graph 2 show ?
At a certain point , the rate of photosyntheiss stops increasing . Now light intensity is no longer the limtign facvtor something rlse is limiting factor .
What three other thins affect the rat eof phtosynthesi s.
-Co2 conc
-temperature
-amout of chlorphyll in leaves .
(can chanhe temp and con2 conc but not chlorphyll in leaves .
Limitng factor co2 graph , what does the graph sho .
- The grpah shows the same experiment as graph 2 but with a higher cocnentraiton of co2 .
- The normal co2 conc shows that at the levels of co2 increases , the rate of photosyntehis sncreases , telling us the conc oof co2 was a limiitn g factor .
What about the higher conc of co2 on the grapgh .
- In the increased co2 conc , rate of photosyntesis hasn’t changes , co2 was no longer limiitng factor ..
- As the high levels of co2 meant there was plenty of co2 available .
Limiting factor , temp graph , what does the higher temperatrue show ?
- At the higher temperature , the rate of photosyntheis has increased .
- Telling us the that temp was the limting factor .
What if we increase he temperature toomuch ?
-The enzymes in the lead start to denature and the rate of photosynthesis will fall .
Why do farmers want to increase the rate of photosyntehsis ?
- As this increases the yield of crop sthey produce .
- To do this , the farmed add light and heat to their greenhosues , as well as extra co2 (they exploit the limiting factors of photosyntheis s).
Problem with exploiting limiting actor in photosyhteis .
extra costs has to be justified by the increase in yield .
-So gardnerres use oil burners as there rlease heat and CO2 at the same time .
What is the first stage for the Photosynthesis RQP ?
1.Start by taking a boiling tube and placing it ten cm away from an LED light source .
Why is an LED light source used ?
- As these do not release very much heat .
- Too much ehat woud change the temperature of the experiment .
What to d if you used a normal light for the RQP ?
-We need to place a beaker of water between the light and boiling tube as the water is absorbed , heat produced from the light bulb .
What is the second stage for the Photosynthesis RQP ?
- Now we fill the boilign tube with soidum hydrogen carbonate solution .
- Sodium hydrogen carbonate solution releases Co2 NEEDED FOR PHOTOSYNTHEIS .
What is the third stage for the Photosynthesis RQP ?
-Put a piece of pondweed into the boing tube with the cut end at the top .
What is the fourth stage for the Photosynthesis RQP ?
Leave this for five minutes , to acclimitaise to the conditions of the boiling tube .
What is the fifth stage for the Photosynthesis RQP ?
- We should start seeing bubbles of gas being produced from the cut end of the pondweed
- This gas is oxygen that is produced by photosyntheiss .
What is the sixth stage for the Photosynthesis RQP ?
NOw we start a stopwatch and count the number of bubbles produced in one minute .
-Then repeat two more times to calculate mean number of bubbles pordue in one minute .
What is the seventh stage for the Photosynthesis RQP ?
Do this hwole epxeriemnt again from the start t 20cm , 30 cm and 40 cm .
What is the porblem with counting the number of bubbles in the RQP ?
- Number of bubbles can be too fast to count accurately .
- The number of bubbles are not always the same size . A large bubble would cont the same as a small bubble .
- WE CAN SOLVE THIS PROBLEM- by measuring the volume of oxygen produced instead of counting bubbles .
What is the first stage of measuring the volume of oxygen ? RQP
-Place te pond weed under a funnel and catch the bubbles using measuring cylinder full of ater .
What is the second stage of measuring the volue of oxygen RQP ?
Then se the measuring cylinder to measure the volume of oxygen gas porduced .
RQP , What does the graph show ?
-If we plot the mean number of bubbles per minute . volume of oxygen per minute agaisnt the disance from the lamp of pondweed .
RQP , what does the grpah show (2) ?
-If we double the disance than he number of bubbles per minute falls by four .
10-20 numbe rof bubbles fall by four .
20-40 , number of bubbles fall by four . Known as inverse square law
What is the Inverse sqaure law ?
-If we double the distance , the light intensity falls by four times .
As we need light for phtosyntheiss , that also causes the number of oxygen bubbles to fall by four times .
One use of photosynthesis form glucose ?
- Release energy in respiration .
- Respiration takes place in the mitochondria .
Second use of photosynthesis form glucose ?
-Photoysnthesis also producs gluose druing day not at night as there is no light .
-But plant cells respire all the time including at night .
Second use of gluscose is to produce the insoluble stroage molecule starch .
-The starch can then be converted back into glucose , by the plant when it is needed .
Third use of photosynthesis form glucose ?
- Some plants glucose produced by photsyngtehsis is converted into fuels and iols .
- Fuels and oils are used by the plnt as a storage form of energy .
Fourth use of photosynthesis form glucose ?
- Pants are enclosed in a cell wall .
- The cell wall cotains moelcule celluse which gives it strenghth .
- The cellulose is made forom the glucose produced by phtosynthesis .
Fifth use of photosynthesis form glucose ?
- Glucose is produced by photosyntheis used to produce aminoa cids .
- Amino acids are used by the plant to syntheissie proteins (peas are good soruce of peas ).
How do plants make amino acids from glucose ?
-Planta absor nitrate ionss and other mienral ions from soil .
Algae do this by absorbing ions in waer around them .
List some leaf adaptations ;
- Broad leaves , giving them a big surface area for light to fall on .
- Leaves thin , so diffusion distnces for gaseshsort .
- Chloroplast has chlorphyl oto absorb light .
More leaf adapations ?
- eaves hae veins , whic bring them plent of water in the xylem to the clells of leaves and remove the products of photsyntehsis in the phloem .
- Air spaces to allow co2 to get into cells and oyxgen to leave by diffusion .
- Guard cells in stomata to regulate gas exchange
