Photosynthesis

Question 1

Where does the light independent reaction take place

Answer 1

In the stroma

Question 2

Where does light dependant reaction take place

Answer 2

In the grana

Question 3

What is the significance of the leaf to photosynthesis

Answer 3

Large SA to capture light
Air spaces in the spongy mesophyll to allow co2 to diffuse
Thin so light can penetrate

Question 4

What is the significance of the chloroplast to photosynthesis

Answer 4

Large Sa for max absorption of light
Rotate within palisade

Question 5

How are plants cells significant in photosynthesis

Answer 5

Transparent cuticle and epidermis so light penetrates through to the mesophyll
Large vacuole in palisade cells
Chloroplasts form a single layer so they don’t shade each other

Question 6

How to chloroplasts act as transducers

Answer 6

Turn light energy into chemical energy

Question 7

What wavelengths does chlorophyll a absorb

Answer 7

435 to 680
Blue or green light

Question 8

What wavelength does chlorophyll b absorb

Answer 8

480 to 650
Yellow or green

Question 9

What does b carotene absorb

Answer 9

425 to 480 orange

Question 10

What does xanthophyll absorb

Answer 10

400 to 500
Yellow

Question 11

What does an absorption spectrum show

Answer 11

How much light a particular pigment absorbs at different wavelengths

Question 12

What does an action spectrum show

Answer 12

Rate of photosynthesis at different wavelengths of light

Question 13

What is the enzyme in the light independent reaction

Answer 13

Rubisco

Question 14

How can carbohydrates be synthesised from Calvin cycle

Answer 14

Fructose bisphosphate can be converted to glucose and added to fructose to make sucrose for transport around plant

Question 15

How can fats be synthesised from the Calvin cycle

Answer 15

Acetyl co enzyme A can be made from GP and make fatty acids
TP can be made into glycerol
Fatty acids and glycerol combine to make triglycerides

Question 16

how do chloroplasts act as transducers

Answer 16

they turn light energy into chemical energy

Question 17

what is the structure of a photosystem

Answer 17

located in the thylakoid membrane
consists of an antenna complex which contains the pigments and a reaction centre

Question 18

what is cyclic photophosphoryation

Answer 18

when ATP can be produced by electrons that take a cyclical pathway and are recycled back into chlorophyll A in ps1

Question 19

what is non cyclic photophosphorylation

Answer 19

ATP produced by electrons that take a linear pathway from water , through ps1 and ps2 to NADP which they reduce

Question 20

what is a summary of cyclic phosphorylation

Answer 20

ps1 absorbs photons which excites chlorophyll molecules
electrons are emitted and picked up by an electron carrier and then passed down an electron transport chain and transported back to ps1
energy released down ETC phosphorylates ADP to ATP

Question 21

what is a summary of non cyclic phosporylation

Answer 21

electrons are not returned to ps1 so chlorophyll has a positive charge , which is neutralised by electrons from ps2
electrons from ps2 are excited and pass down electron transport chain to ps1 which makes energy available for phosphorylation to ADP

Question 22

what is a summary of the light independent reaction

Answer 22

RuBP combines with co2 catalysed by ribulose bisphosphate carboxylase
6c compound splits to two molecules of GP
GP is reduced to TP by reduced NADP with energy from ATP
NADP reforms

Question 23

how does co2 concentration affect photosynthesis

Answer 23

as it increases the rate of light independent reaction increases

Question 24

how does light intensity affect the rate of photosynthesis

Answer 24

in darkness light independant reaction is still possible but no oxygen is produced
as light intensity increases light dependant reaction increases so rate increases
at levels that are too high photosynthetic pigments are damaged which decreases rate

Question 25

what is the light compensation point

Answer 25

the light intensity at which a plant has no net gas exchange as the volume of gases used and the volume of gases produced in respiration and photosynthesis are equal

Question 26

How is an action spectrum measured

Answer 26

mass of carbohydrate synthesised by plants at different wavelengths of light