light dependent stage

Question 1

what are the two stages of photosynthesis

Answer 1

light dependent
light independent

Question 2

where does the light dependent stage

Answer 2

takes place in the thylakoid membrane and photosystems

Question 3

During the light dependent stage, light energy is used to break down water to produce…

Answer 3

Hydrogen ions
electrons
oxygen

Question 4

what is photolysis

Answer 4

when light energy is used to break down water to produce products of oxygen, protons and electrons

Question 5

in photosystem I, What pigment is in the primary reaction centre

Answer 5

chlorophyll A, p700.

Question 6

in photosystem II, What pigment is in the primary reaction centre

Answer 6

chlorophyll B, p680

Question 7

what are some functions of water

Answer 7

• maintains plant turgidity
• produces oxygen and protons
• donates electrons to chlorophyll to replace those lost when light strikes chlorophyll

Question 8

oxygen is produced by photolysis, where is it used

Answer 8

Used in aerobic respiration by plants or when light intensity is high, it is diffused out of stomata.

Question 9

what is photophorylation

Answer 9

process of generation of atp from adp and an inorganic phosphate when light is present

Question 10

what are the two types of phosphorylation and what are the differences

Answer 10

cyclic- involves only PSI, produces less atp than non cyclic

non cyclic- involves ps1 and ps2, produces atp, reduced NADP and O2

Question 11

what is an electron carrier

Answer 11

it captures excited electrons from chlorophyll in the photosystems

it is a protein embedded in thylakoid membrane with an iron centre which can accept electrons and donate them to the next electron carrier protein

Question 12

what photosystems does non cyclic phosphorylation use

Answer 12

PSII and PSI

Question 13

what photosystem does cyclic phosphorylation use

Answer 13

PSI only

Question 14

how is atp produced in the light dependent stage

Answer 14

some is released from electrons as they pass through the electron transport chain.

Also formed when protons pass through the special channels in the thylakoid membrane, the flow of protons produces atp

Question 15

what causes excitation of electrons out of the chlorophyll in photosystems

Answer 15

when light strikes the photosystems, the light energy is channeled to the primary pigment in the centre of the reaction centre- chlorophyll.
This light energy excites a pair of electrons in the chlorophyll molecules

Question 16

What is chemiosmosis

Answer 16

the transport of protons from the thylakoid space/ lumen to the stroma using special channels and ATP synthase in the thylakoid membrane
to produce ATP from ADP + Pi

Question 17

what is photophosphorylation

Answer 17

Process of light energy producing ATP from ADP and inorganic phosphate

Question 18

energy is used to pump protons across the thylakoid membrane into the thylakoid space. Where is this energy derived from.

Answer 18

The energy comes from when electrons pass electron carriers, some energy is released from the electrons.
This energy pumps protons into the space.

Question 19

Summarise cyclic phosphorylation

Answer 19

light strikes PSI and chlorophyll at reaction centre gains energy, exciting its electrons.
Electrons pass to an electron transport chain
they then pass back to ps1.
producing a small amount of atp when electrons pass through the etc

Question 20

Which produces LESS atp,
cyclic or non cyclic phosphorylation

Answer 20

Cyclic photophosphorlylation produces less atp than non cyclic

Question 21

what is the final electron acceptor in Light dependent

Answer 21

NADP

Question 22

what does NADP require to become reduced

Answer 22

electrons
hydrogen

Question 23

in chemiosmosis, a proton gradient is produced where is the gradient produced

Answer 23

HIgh in thylakoid space,
low in stroma

Question 24

what is atp synthase

Answer 24

an enzyme catalysing the synthesis of adp + pi into atp

Question 25

what is reduction

Answer 25

gain of an electron

Question 26

what is the equation for photolysis

Answer 26

2h20= 4h + 4e + o2