2. Describe the process of light reaction which occurs in green
plants. [8]Answer:
▪ when photon of light reach photosystem II, the light energy is absorbed by chlorophyll in photosystem II.
▪ The aborption of light by
chlorophyll causes electrons to be excited to higher energy level
▪ electron hole found
in photosystem II, as a result of
excited electron must be filled
▪ this is done by
splitting of water molecules by water splitting enzyme that give rise to
electron that fill in the hole
▪ oxygen gas is released in the process as
well▪ As electron cascade dowm electron transport chain, ATP is produced
▪ the production of ATP is called photophosphorylation because it is
generated through light reaction.▪ when photon of light reach photosystem II, the light energy
is absorbed by chlorophyll of photosystem I
▪ absorption of
light energy by chlorophyll causes electron to be excited to higher energy
level and is accepted by electron acceptor
▪ electron hole is filled by electron cascading down
from photosystem II
▪ electron acceptor in photosystem I passes the excited electron to Fd and then to NADP+ reductase
▪ NADP+ reductase passes the electron to NADP+
to produce NADPH
▪ NADPH
will provide reducing power for synthesis of sugar in Calvin cycle.
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