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The Leaving Certificate Examination (Irish: Scrúdú na hArdteistiméireachta), commonly referred to as the Leaving Cert or (informally) the Leaving (Irish: Ardteist), is the final exam of the Irish secondary school system and the university matriculation examination in Ireland.
Photosynthesis usually refers to oxygenic photosynthesis, a process that produces oxygen. Photosynthetic organisms store the chemical energy so produced within intracellular organic compounds (compounds containing carbon) like sugars, glycogen , cellulose and starches .
The photosynthetic efficiency (i.e. oxygenic photosynthesis efficiency) is the fraction of light energy converted into chemical energy during photosynthesis in green plants and algae. Photosynthesis can be described by the simplified chemical reaction 6 H 2 O + 6 CO 2 + energy → C 6 H 12 O 6 + 6 O 2
The light excites an electron in the pigment P680 at the core of photosystem II, which is transferred to the primary electron acceptor, pheophytin, leaving behind P680 +. The energy of P680 + is used in two steps to split a water molecule into 2H + + 1/2 O 2 + 2e - ( photolysis or light-splitting ).
This is one of two core processes in photosynthesis, and it occurs with astonishing efficiency (greater than 90%) because, in addition to direct excitation by light at 680 nm, the energy of light first harvested by antenna proteins at other wavelengths in the light-harvesting system is also transferred to these special chlorophyll molecules.
In biology, a light-harvesting complex or LHC is an aggregate consisting of proteins bound with chromophores (chlorophylls and carotenoids) that play a key role in photosynthesis. LHCs are arrayed around photosynthetic reaction centers in both plants and photosynthetic bacteria and collect more of the incoming light than would be captured by ...
The CO 2 compensation point (Γ) is the CO 2 concentration at which the rate of photosynthesis exactly matches the rate of respiration. There is a significant difference in Γ between C 3 plants and C 4 plants: on land, the typical value for Γ in a C 3 plant ranges from 40–100 μmol/mol, while in C 4 plants the values are lower at 3–10 μmol/mol. Plants with a weaker CCM, such as C2 ...
Chlorophyll a is the most common of the six, present in every plant that performs photosynthesis. Each pigment absorbs light more efficiently in a different part of the electromagnetic spectrum . Chlorophyll a absorbs well in the ranges of 400–450 nm and at 650–700 nm; chlorophyll b at 450–500 nm and at 600–650 nm.