Energy Transfer - Photosynthesis

Question 2

What is the equation for photosynthesis?

Answer 2

6CO₂ + 6H₂O -> C₆H₁₂O₆ + 6O₂

Question 3

Define a metabolic pathway

Answer 3

a series of enzyme controlled small reactions

Question 4

Define phosphorylation

Answer 4

adding phosphate to a molecule

Question 5

Define photophosphorylation

Answer 5

adding phosphate to a molecule using light

Question 6

Define hydrolysis

Answer 6

Splitting a molecule using water

Question 7

Define photolysis

Answer 7

Splitting of a molecule using light

Question 8

Define decarboxylation

Answer 8

removing CO₂ from a molecule

Question 9

Define dehydrogenation

Answer 9

removing H from a molecule

Question 10

Define a coenzyme

Answer 10

a molecule that aids enzymes

Question 11

What coenzyme is used in photosynthesis?

Answer 11

NADP

Question 12

What is the function of NADP in photosynthesis?

Answer 12

transfers hydrogen from one molecule to another

Question 13

What are the reactions of photosynthesis?

Answer 13

Light dependant reaction

Light independant reaction

Question 14

Where does the light dependent reaction occur?

Answer 14

thylakoid membrane

Question 15

What absorbs light energy in photosynthesis?

Answer 15

photosynthetic pigments

Question 16

What is the function of photosynthetic pigments?

Answer 16

to absorb light energy and convert it into chemical energy

Question 17

what is photoionisation?

Answer 17

when light energy excites an electron off of an atom, creating a positive ion

Question 18

what are the overall stages of the light dependent reaction?

Answer 18

1. light energy absorbed by chlorophyll in photosystems, which then photoionises the chlorophyll as the electrons leave the molecule
2. some of the energy from the electrons is used to convert ADP to ATP and reduce NADP
3. ATP transfers energy and NADP transfers H to the light independent reaction
4. during this H₂O oxidised to O₂​

Question 19

what happens in the light dependent reaction of photosynthesis after the water is photolysed?

Answer 19

electrons from water used to replace ones lost from chlorophyll

electrons from chlorophyll move down electron transport chain

energy lost is used to transport H+ into the thylakoid, forming a proton gradient

protons move down the conc gradient into the stroma via ATP synthase, causing the ATP to be formed from ADP + inorganic phosphate

Question 20

how is reduced NADP formed in the light dependent reaction of photosynthesis?

Answer 20

light energy absorbed by PSI, exciting electrons to higher energy level

electrons transferred to NADP along with H+ from stroma to form reduced NADP

Question 21

what is chemiosmosis?

Answer 21

movement of ions across a partially permeable membrane, down the electrochemical gradient

Question 22

when is chemiosmosis used in the light dependent reaction?

Answer 22

when electrons flow down the electron transport chain, creating a proton gradient across the membrane to catalyse ATP synthesis

Question 23

what is the light independent reaction also known as?

Answer 23

the calvin cycle

Question 24

where does the calvin cycle take place?

Answer 24

the stroma of chloroplasts

Question 25

what is the first stage of the calvin cycle?

Answer 25

carbon dioxide combined with ribulose biphosphate to form 2 molecules of glycerate 3-phosphate

Question 26

what happens to the glycerate 3-phosphate generated in the first stage of the calvin cycle?

Answer 26

hydrolysis of ATP (from light dependent reaction) provides energy to turn it into triose phosphate

this reaction also requires protons from reduced NADP, forming NADP

Question 27

what happens to triose phosphate after it is generated in the calvin cycle?

Answer 27

some is converted into useful organic compounds (eg glucose) and some continues in the calvin cycle to regenerate ribulose biphosphate

Question 28

how is ribulose biphosphate regenerated in the calvin cycle?

Answer 28

5 out of the 6 triose phosphates produced are used to regenerate it

this uses the resut of the ATP produced by the light dependent reaction

Question 29

how many times does the calvin cycle need to turn to produce one hexose sugar?

Answer 29

six