Edexcel A2 Biology Unit 4
PHOTOSYNTHESIS
1 INTRODUCTION - u watch it @ home #
2 Grandma story - Value of Sharing
Group Assessment
3 PROJECT
Bill Gates: Artificial Photosynthesis Can Produce Clean Fuel for the Cars of Tomorrow
Artificial Photosynthesis
Photosynthesis is an essential natural process that keeps not just plants, but just about everything else on Earth alive — including us. When plants convert carbon dioxide and water into carbohydrates, they feed themselves and emit oxygen for us to breathe. But what if we took a page out of nature’s book, and figured out how to use sunlight to produce hydrogen for fuel? “If it works it would be magical,” Bill Gates told Reuters, “because with liquids you don’t have the intermittency problem batteries. You can put the liquid into a big tank and burn it whenever you want.”
Artificial photosynthesis (AP) aims to split water in oceans, and possibly even rivers, into its hydrogen, oxygen, and carbon components using sunlight. Hydrogen produced via AP is readily usable in the fuel cells of electric cars being manufactured right now, and it can also be used to store solar energy. Liquid fuels like hydrogen have a distinct advantage over batteries, as they are lighter and less bulky.
Combining the fruits of AP in the right proportions produces methanol, which can fuel combustion engines. China has become the largest consumer of methanol in the world, blending it with gas at levels of 15 percent or less for consumer vehicles at gas stations, and running transit vehicles on blends as high as 85 percent methanol.
A variation on the AP process was also used to metabolically engineer nitrogen-generating bacteria to produce nitrogen-based fertilizer right in soil —a technique that could boost crops yields in places without ready access to conventional fertilizers. Eventually, these kinds of bacteria might be able to “breathe in” the hydrogen produced by AP and use it to produce a range of goods, including drugs, fertilizers, fuels, and plastics, all determined by the metabolic engineering of the bacteria.
TEAM Work
Design a model of artificial photosystem. You can search intenet to propse your model and write an attractive magazine article with pictures of it. Assume you going to submit this to Advances of Wales
https://businesswales.gov.wales/innovation/advances-wales
4 Grandma story , the vaue of becoming humble
Grandma story - Accountability, Leadership and Teamwork
5 LIGHT DEPENDNT REACTION
6 Grandma stories - When you start a job
7. Individual project
Guidlines to make a poster
Grandma story- World is full of everything. You have no options. Face the challenegs.
PRACTICAL
CHROMOATOGRAPHY
Heading 1
Question 3: What is the Kautsky effect?
Kautsky and Hirsch (1931) observed for several types of leaves that a dark-to-light transition is characterized by an initial fast increase of the fluorescence intensity followed by a slow decrease to a minimum level, after which the fluorescence intensity remains at this low intensity. The authors assigned the stable low level of fluorescence to steady-state photosynthesis. They noted further that the slow fluorescence decrease had the same time dependence as the induction of CO2 assimilation and concluded that the fast fluorescence rise reflects a photochemical reaction since it was insensitive to cyanide and temperature chan- ges. The fluorescence changes occurring during induction of photosynthesis have been studied intensively during the last 50 years and, in honor of the first publication on this phenomenon, such a fluorescence transient is called a Kautsky transient, and the changes in the fluorescence intensity the Kautsky effect.
In Fig. 1 examples of the first 10 s of Kautsky transients measured on several angiosperm and gymnosperm plants are shown on a logarithmic time- scale.
The fluorescence rise phase (OJIP) reflects the reduction of the photosynthetic electron transport chain (see Kalaji et al. 2014a for a more comprehensive discus- sion) and its kinetics, as illustrated in Fig. 1, are quite similar for all photosynthetic organisms. The fluorescence decrease has kinetics that differ quite strongly between different types of photosynthetic organisms (in Fig. 1 angiosperm vs. gymnosperm plants). The S and M steps observed in transients of gymnosperm species lack/are hidden in transients of angiosperm species. Using 820-nm transmission measurements it was shown that the initial fluorescence kinetics beyond P depend strongly on the activation of electron flow at the PSI acceptor side, asso- ciated with the activation of ferredoxin-NADP? reductase (FNR) (Kautsky et al. 1960; Munday and Govindjee 1969; Satoh 1981; Harbinson and Hedley 1993; Schansker et al. 2003, 2008; Il ́ık et al. 2006). Fluorescence then declines within 3–5 min with the onset of photosynthetic CO2 fix- ation until it reaches a lower, steady-state fluorescence intensity (FS). In fully photosynthetically active leaves this steady-state level, especially at high light intensities, is usually close to the FO level (e.g., Flexas et al. 2002).
Question 4: What is quantum yield?
In a general sense, the quantum yield can be defined by an action, e.g., oxygen evolution or a stable charge separation, divided by the number of photons that has to be absorbed
Fig. 1 Chl a fluorescence induction transients measured on angios- perm (sugar beet, camellia and tobacco) and gymnosperm (Ginkgo and yew) leaves. The fast induction kinetics