3.2 - Photosynthesis

Question 1

What is absorption spectra?

Answer 1

A graph showing the wavelengths of light absorbed by a pigment

Question 2

What is action spectra?

Answer 2

A graph of the rate of photosynthesis against each wavelength of light absorbed by a pigment

Question 3

What is the Calvin cycle?

Answer 3

Light-independent reaction - The second stage of photosynthesis in which the products of the light-dependent stage and carbon dioxide are used to build organic molecules. It does not require light energy and takes place in the stroma.

Question 4

Define chlorophyll

Answer 4

A photosynthetic pigment located in the thylakoids of the chloroplasts that absorbs light energy. There are two main types, chlorophyll a and chlorophyll b.

Question 5

Explain what chloroplasts are

Answer 5

An organelle found in plants and algae that is the site of photosynthesis

Question 6

What does chromatography mean?

Answer 6

The process of separating different substances from a mixture

Question 7

What is cyclic photophosphorylation?

Answer 7

The formation of ATP involving photosystem I only

Question 8

Define what Glycerate-3-phosphate (GP) is

Answer 8

A three-carbon molecule that is reduced by reduced NADP in the light-independent stage of photosynthesis to form 2 molecules of TP. This requires ATP

Question 9

Explain what the light-dependent reaction is

Answer 9

the fist stage of photosynthesis that uses light energy to produce ATP, reduced NADP and oxygen. It takes place in the thylakoids of the chloroplast

Question 10

What is the light-harvesting system? (Antennae Complex)

Answer 10

A collection of protein and chlorophyll molecules found in the thylakoid membranes of chloroplasts that absorbs light energy of varying wavelengths and transfers it to the reaction centre. It is also known as an antennae complex

Question 11

What is the light-independent stage?

Answer 11

The second stage of photosynthesis, also known as the Calvin cycle, in which the products of the light-dependent stage and carbon dioxide are used to build organic molecules. It does not require light energy and takes place in the stroma

Question 12

What is a limiting factor?

Answer 12

A variable that limits the rate of a particular reaction

Question 13

Define magnesium

Answer 13

An inorganic nutrient required in plant metabolism for the production of chlorophyll

Question 14

What is NADP?

Answer 14

A coenzyme that becomes reduced when it takes up hydrogen atoms during the light-dependent stage of photosynthesis, forming reduced NADP

Question 15

What is nitrogen?

Answer 15

An inorganic nutrient required in plant metabolism for the production of amino acids, nucleotides and chlorophyll.

Question 16

What is non-cyclic photophosphorylation?

Answer 16

The formation of ATP and reduced NADP involving both photosystems I and II

Question 17

Define oxidation

Answer 17

The loss of electrons, gain of oxygen or loss of hydrogen in a substance

Question 18

What is photolysis?

Answer 18

the splitting of a molecule of water in the presence of light that occurs during the light-dependent stage of photosynthesis. This produces protons, electrons and oxygen:

H2O -> 2H+ + 2e- + 1/2 O2

Question 19

Define photosynthesis

Answer 19

A complex metabolic pathway that synthesises organic molecules in the presence of light. It consists of 2 main stages: light-dependent and light-independent reactions.

6CO2 + 6H2O > C6H12O6 + 6O2

Question 20

What are photosynthetic pigments?

Answer 20

Molecules present in the chloroplasts that absorb certain wavelengths of light e.. chlorophyll a, chlorophyll b, xanthophylls and carotenoids

Question 21

What is a photosystem?

Answer 21

A protein complex consisting of a light-harvesting system and reaction centre, hat is involved in the absorption of light and transfer of electrons in photosynthesis. There are 2 types, photosystems I and II.

Question 22

What is a reaction centre?

Answer 22

The region of a photosystem where energy is funnelled and photosynthetic reactions take place. It contains 2 chlorophyll a molecules.

Question 23

Define reduction

Answer 23

The gain of electrons, loss of oxygen or gain of hydrogen in a substance

Question 24

What is retention value (R1)?

Answer 24

Calculated using the equation;

Rf = distance travelled by component

Question 25

What is retention value (R1)?

Answer 25

Calculated using the equation;

Rf = distance travelled by component
distance travelled by solvent

Question 26

What is ribulose bisphosphate (RuBP)?

Answer 26

A five-carbon compound that reacts with carbon dioxide in the light-independent stage of photosynthesis, forming 2 molecules of GP

Question 27

What is ribulose bisphosphate carboxylase (Rubisco)?

Answer 27

an enzyme that catalyses the reaction of RuBP and the carbon dioxide in the light-independent stage of photosynthesis

Question 28

What is a transducer?

Answer 28

Something that converts one type of energy into another e.g. chloroplasts transform light energy into the chemical energy of ATP.

Question 29

What is triose phosphate (TP) ?

Answer 29

A three-carbon compound formed in the glycolysis and the light-independent stage of photosynthesis. It may serve as a starting material for the formation of organic molecules or be used to regenerate RuBP.