Photosynthesis

Question 1

Define photosynthesis

Answer 1

the process in plants, from which energy from sunlight is used to convert inorganic
molecules into organic molecules.
carbon dioxide + water = glucose + oxygen

Question 2

Where does the light-dependent reaction occur?

Answer 2

In the thylakoids of the

grana in chloroplasts

Question 3

Light-dependent stage - step 1 - photolysis of water

Answer 3

Photolysis of water requires light energy to break the bonds between oxygen and hydrogen atoms
2H2O = 4H+ + 4e- + O2

Question 4

Light-dependent stage - step 2 - chlorophyll

Answer 4

Chlorophyll molecules absorb light energy via photosystem II, exciting a pair of electrons to a
higher energy level, leaving the chlorophyll molecules ionized.

Question 5

Light-dependent stage - step 3 - electron transport chain

Answer 5

The electron passes through an electron transfer chain to produce ATP, and reaches photosystem I.

Question 6

Light-dependent stage - step 4 - post electron transport chain

Answer 6

The electrons replace the electrons lost in photosystem I when it absorbs light to reduce NADP with the protons created from photolysis

Question 7

Light-dependent stage - step 5 - electrons

Answer 7

The photoionized chlorophylls electrons in photosystem II are
replaced by the electrons from photolysis of water

Question 8

Light-dependent stage - step 6 - Cyclic photophosphorylation

Answer 8

Cyclic photophosphorylation only uses photosystem I, where the electrons are passed back to photosystem I rather than NADP via electron carriers, producing small amounts of ATP

Question 9

Where does the light-independent reaction occur?

Answer 9

in the stroma of

chloroplasts

Question 10

What is the Light-independent stage also known as?

Answer 10

Calvin cycle

Question 11

What is the Light-independent stage dependent on?

Answer 11

1. The Calvin cycle depends on the products from the light dependant stage

Question 12

Describe the Light-independent stage

Answer 12

The fixation of carbon dioxide is catalysed by RuBisCo

5 out of every 6 TP molecules are used to regenerate RuBP instead of producing hexose sugars

Question 13

The rate of photosynthesis is

limited by…

Answer 13

temperature and the
availability of carbon dioxide, water & light
energy.

Question 14

How can you separate photosynthetic

pigments?

Answer 14

Chromatography - identifying them by their Rf value

Question 15

Rf value

Answer 15

distance travelled by solute/distance travelled by solvent