Photosynthesis

Question 1

Label the structure of chloroplast

Answer 1

See notes include
- granum
- lamella
- ribosomes
- stoma
- outer membrane
-inner membrane
- starch grain
- thylakoid
- lipid droplet

Question 2

What photosynthetic pigments do plants contain

Answer 2

Chlorophyll ( a & b)
Carotenoid (b-carotene & xanthophyll)

Question 3

explain why plant benefits from having pigments that absorb different wavelengths
E,g what does chlorophyll absorb

Answer 3

Each pigment absorbs slightly different wavelengths so having different pigments plants maximise the wavelengths of light they can absorb energy from
E.g chlorophyll absorbs blue and red wavelengths of visible light

Question 4

Absorption spectrum shows…

Answer 4

% light of different wavelengths absorbed by isolated pigments

Question 5

What type of light does chlorophyll absorb

Answer 5

Blue and red wavelengths

Question 6

Action spectrum shows..

Answer 6

Rate of photosynthesis of plants exposed to different wavelengths of light

E.g. highest rates of photosynthesis stimulated by blue and red wavelengths of light

Question 7

Def of photosystem

Answer 7

Light- harvesting cluster of pigment molecules in the thylakoid membrane

Question 8

What is photosystem I and photosystem II?

Answer 8

Photosystem I
Reaction centre (cluster of pigment molecules) = chlorophyll A with peak absorption 700nm

Photosystem II
Reaction centre (cluster of pigment molecules) = chlorophyll A with peak absorption 680nm

Question 9

Role of accessory pigments in photosystem
(Examples of pigments)

Answer 9

Accessory pigments (Chlorophyll A & B and carotenoids) pass energy from light to the chlorophyll A at the reaction centre for start of photosynthesis

Question 10

Def of Photophosphorylation

Answer 10

The synthesis of ATP using energy harvested from light

Question 11

The process of cyclic photophosphorylation (photosystem I)
(5 steps)

Answer 11

1) light energy excites electron from chlorophyll A in photosystem I
2) electron passes down electron transport chain (ETC) in the thylakoid membrane
3) energy lost from electron used to pump protons across membrane into thylakoid lumen
4) protons diffuse through ATP synthase & energy is used to synthesis ATP
5) electron returns to chlorophyll molecule

Question 12

Compare photophosphorylation & oxidative phosphorylation
1) organelle
2) location of ETC
3) Location of high [H+]
4) source of high energy electrons

Answer 12

organelle
Photo) Chloroplast
OP) mitochondrion

location of electron transport chain
Photo) thylakoid membrane
OP) inner mitochondrion membrane

location of high H+ concentration
Photo) thylakoid lumen
OP) inter mitochondrion membrane

source of high energy electrons
Photo) chlorophyll A
OP) glucose