Photosynthesis

Question 1

Define photosyntheis

Answer 1

The process of transforming sunlight into chemical energy by converting inorganic compounds into energy rich compounds

Question 2

What is the formula for photosynthesis?

Answer 2

6CO2 + 6H2O. –light+chlorophyll–> C6H12O6 + 6O2

Question 3

Describe features of a chloroplast

Answer 3

Thylakoids: flattened sacs
Grana: stacks of thylakoids membranes containing chlorophyll
Stroma: the liquid interior of the chloroplast

Question 4

Where does photosynthesis occur?

Answer 4

In the chloroplasts

Question 5

What are the two key stages of photosynthesis?

Answer 5

The Light Dependant Reaction

The Light-Independent Reaction

Question 6

What are the key stages of photosynthesis?

Answer 6

The Light Dependant reaction

The Light Independent Reaction (The Calvin Cycle)

Question 7

What is the key difference between the Light Dependant and Light Independent reactions?

Answer 7

The Light Dependant Reaction requires light, while the Light Independent Reaction does not

Question 8

Outline the Light Dependant Reaction

Answer 8

1. Light strikes photosystem II
2. Electrons from P II become excited and escape
3. The chlorophyll takes electrons from water molecules to replace the last ones, this causes water to split into Hydrogen and Oxygen
4. The lost electrons move along the electron transport chain, this causes proteins to pump Hydrogen from the stroma into the thylakoid space
5. Light energy absorbed by Photosystem I also excites electrons and they escape along the E.T.C
6. the lost electrons are replaced by the electrons from Photosystem II
7. The electron energy is used to join NADP with Hydrogen to form NADPH
8. Hydrogen ions pumped into the thylakoid space travel across an ATP Synthase enzyme. The energy of Hydrogen Ions is used to form ATP

Question 9

Define photolysis

Answer 9

The splitting of water into hydrogen ions and oxygen molecules

Question 10

What are the products of the Light Dependant Reaction?

Answer 10

ATP and NADPH

Question 11

Where does the Light Dependant Reaction Occur?

Answer 11

On the thylakoid membranes

Question 12

Where does the Light Independent Reaction occur?

Answer 12

In the stroma

Question 13

Define Carbon Fixation

Answer 13

the process where carbon dioxide molecules in the chloroplasts are joined with RuBP to start the processes in the Calvin Cycle

Question 14

What is RuBP?

Answer 14

Ribulose Triphosphate

a 5 carbon compound that binds with CO2 at the beginning of the Calvin Cycle

Question 15

What is Rubisco?

Answer 15

the enzyme that catalyses the reaction of RuBP + CO2

Question 16

What cycle is involved in the Light Independent reaction?

Answer 16

The Calvin Cycle

Question 17

Outline the Light Independent Reaction

Answer 17

1. CO 2 molecules in the stroma combine with a 5 carbon compound RuBP to form a 6C compound (Carbon fixation)
2. The 6C compound splits into 3C compounds and phosphates are added
3. ATP + NADPH are used to rearrange the structure of the molecules in a number of steps
4. A 3C compound is released and will be used to form glucose
5. The remaining molecules reform RuBP
6. The newly formed RuBP is used in the cycle again. the second Cycle produces another 3C compound to form glucose

Question 18

Summarise the Light Dependant Reaction

Answer 18

energy from sunlight is absorbed by chlorophyll and converted into chemical energy in the form of electron carrier molecules like ATP and NADPH

Question 19

Summarise the Light Independent Reaction

Answer 19

carbohydrate molecules are assembledfrom carbon dioxide using the chemical energy harvested during the light-dependent reactions

Question 20

What are the inputs of photosynthesis?

Answer 20

Carbon Dioxide, Water and Sunlight

Question 21

What are the outputs of photosynthesis?

Answer 21

Glucose and Oxygen