photosynthesis

Question 1

what is a metabolic pathway?

Answer 1

series of small reactions controlled by enzymes

Question 2

what is phosphorylation?

Answer 2

adding phosphate to a molecule

Question 3

what is photophosphorylation?

Answer 3

add phosphate group using light

Question 4

what is photolysis?

Answer 4

splitting of a molecule using light

Question 5

what is hydrolysis?

Answer 5

splitting of a molecule using water

Question 6

what is decarboxylation?

Answer 6

removal of carbon dioxide from a molecule

Question 7

what is dehydrogenation?

Answer 7

removal of hydrogen from a molecule

Question 8

what is a redox reaction?

Answer 8

reaction that involves oxidation and reduction

Question 9

why do plants need energy?

Answer 9

photosynthesis 
active transport
DNA replication
cell division 
protein synthesis

Question 10

what is the word equation for photosynthesis?

Answer 10

carbon dioxide + water > oxygen and glucose

Question 11

what is the chemical equation for photosynthesis?

Answer 11

6CO2+6H20>6O2+C6H12O6

Question 12

why is ATP production important for plants?

Answer 12

cannot get their energy directly from glucose- needs to be released from glucose by respiration

Question 13

why is ATP a good energy source?

Answer 13

releases small amounts of energy at a time to prevent wastage
transfers energy by transferring a phosphate group to make other molecules more reactive
small and soluble so easily transported
easily broken down so energy is released easily
cannot pass out of a cell so always has an energy supply

Question 14

what does it mean if a molecule is reduced?

Answer 14

gains electrons, gains hydrogen, loses oxygen

Question 15

what does it mean if a molecule is oxidised?

Answer 15

loses electrons, loses hydrogen, gains oxygen

Question 16

what is a co enzyme?

Answer 16

molecule that aids an enzyme

transfers a chemical group from one molecule to another

Question 17

what is the co enzyme for photosynthesis?

Answer 17

NADP

Question 18

what does NADP do?

Answer 18

transfers hydrogen from one molecule to another

Question 19

what is the structure of a chloroplast?

Answer 19

has an outer and inner membrane, has thylakoids/granum, lumen and stroma

Question 20

what is a photosynthetic pigment?

Answer 20

coloured biological compound found in chloroplasts and photosynthetic bacteria, captures light for photosynthesis

Question 21

what are the photosynthetic pigments found in chloroplasts?

Answer 21

chlrophyll a, chlrophyll b and carotene

Question 22

what are proteins and pigments called when they are together?

Answer 22

photosystems

Question 23

what colour light does chlorophyll reflect?

Answer 23

green

Question 24

what colour light do carotenoids reflect?

Answer 24

red/orange/yellow

Question 25

what wavelength does photosystem I best absorb light at?

Answer 25

700nm

Question 26

what wavelength does photosystem II best absorb light at?

Answer 26

680nm

Question 27

what are the two stages of photosynthesis?

Answer 27

light dependent reaction and light independent reaction

Question 28

how do the two stages of photosynthesis differ in terms of light energy?

Answer 28

light dependent reaction needs light energy, whereas light independent reaction does not directly

Question 29

how do the two stages of photosynthesis differ in terms of location?

Answer 29

light independent reaction occurs in the thylakoid membranes of the chloroplast, light independent reaction occurs in the stroma of the chloroplasts

Question 30

how do the two stages of photosynthesis differ in terms of ATP?

Answer 30

in the light dependent reaction light energy is converted to chemical energy (ATP) in the light independent reaction glucose is made using ATP

Question 31

what are photosystems linked by?

Answer 31

electron carriers (which are proteins that transfer electrons)

Question 32

what is the electron transport chain?

Answer 32

chain of proteins through which excited proteins flow

Question 33

what are the stages of the light dependent reaction? (non cyclic photophosphorylation)

Answer 33

1) light energy absorbed by PSII, which excites electrons in chlorophyll 2) move to a higher energy level, and leave chlorophyll via photoionisation 3) electrons move down the electron transport chain to PSI 4) excited electrons must be replaced, so photolysis occurs to split water into protons, electrons and oxygen 5) excited electrons lose energy as they move down the electron transport chain 6) this energy is used to transport proteins along the thylakoid membrane 7) the thylakoid membrane has a higher concentration of protons than the stroma, resulting in a proton gradient across the thylakoid membrane 8) protons move down the concentration gradient in chemiosmosis to the stroma via ATP synthasse 9) phosphorylation occurs as ATP is synthesises from ADP and inorganic phosphate 10) light energy is absorbed by PSI which excites the electrons again, so they move to a higher energy level 11) electrons are transferred to NADP alongside a proton from the stroma to form reduced NADP

Question 34

what are the products of non cyclic photophosphorylation?

Answer 34

ATP, reduced NADP and O2

Question 35

why is cyclic photophosphorylation cyclic?

Answer 35

electrons from chlorophyll are passed back to PSI by electron carriers, so electrons are recycled and repeatedly flow through PSI