Photosynthesis

Question 1

Where does the light dependent stage occur

Answer 1

the thylakoid membranes

Question 2

The basic stages of the light dependent stage

Answer 2

1- photolysis of water
2- synthesis of ATP from ADP by photophosphorylation
3- formation of NADPH by the reduction of NADP

Question 3

Photolysis of water

Answer 3

UV light enters PSII and catalyses the photolysis of water, producing 1/2 of an O2 molecule, 2 H+ ions and 2 electrons

Question 4

Photophosphorylation (until PSII)

Answer 4

1- the electrons become excited and are carried along a series of electron carriers, down successively lower energy levels
2- this allows energy to be released and used in synthesis of ATP by photophosphorylation.

Question 5

Photophosphorylation (PSI and after)

Answer 5

1- the electrons enter PSI and are again excited by UV light
2- the excited electrons are carried, along another electron transport chain by carriers at successively lower energy levels, to NADP and reduce it to NADPH, along with the H+ ions produced from photolysis

Question 6

What does an absorption spectra show

Answer 6

The relative absorption of light by different pigments at particular wavelengths

Question 7

What does an action spectra show

Answer 7

The rate of photosynthesis that takes place at different wavelengths of light

Question 8

The process of light harvesting

Answer 8

Light energy is absorbed by a pigment, and causes it to to be excited. Through resonance transfer, the light energy is transferred through the antenna complex until it reaches the reaction centre, where chlorophyll-a is located in large quantities