Photosynthesis

Question 1

granum

Answer 1

inner part of chloroplasts made of stacks of thylakoid membranes where the light-dependent stage takes place

Question 2

photosynthetic pigment

Answer 2

pigment that absorbs specific wavelengths of light and traps the energy associated with light

Question 3

photosytem

Answer 3

system of photosynthetic pigments found in thylakoids- each contains 300 molecules of chlorophyll that trap photons and pass energy to a primary pigment reaction centre (chlorophyll a)

Question 4

stroma

Answer 4

fluid-filled matrix of chloroplasts where light-independent stage takes place

Question 5

thylakoid

Answer 5

flattened membrane-bound sac found inside chloroplasts- contains photosynthetic pigments/photosystems and site of light-dependent

Question 6

electron carriers

Answer 6

molecules that can accept one or more electrons and then donate them to another carrier e.g. ferredoxin, NAD, NADP

Question 7

NADP

Answer 7

a coenzyme and electron and hydrogen carrier

Question 8

photophosphorylation

Answer 8

generation of ATP from ADP + Pi in the presence of light

Question 9

calvin cycle

Answer 9

metabolic pathway of light-ind stage to make organic compounds

Question 10

GP

Answer 10

intermediate compound in the calvin cycle

Question 11

RuBP

Answer 11

a five-carbon compound present in chloroplasts, a carbon dioxide acceptor

Question 12

TP

Answer 12

a three-carbon compound and product of calvin cycle used to make other larger organic molecules

Question 13

autotroph

Answer 13

organisms that use sunlight to synthesise large organic molecules from simple organic molecules which form the building blocks of living cells

Question 14

heterotroph

Answer 14

an organism that ingest/absorbs organic carbon to produce energy and synthesise

Question 15

chemotroph

Answer 15

organisms that obtain energy through a chemical process (chemosynthesis) rather than photosynthesis

Question 16

photoautotroph

Answer 16

organisms that photosynthesise because they use light as a source for autotrophic nutrition

Question 17

photon

Answer 17

a particle of light, each containing an amount of energy

Question 18

products of photosynthesis

Answer 18

monosaccharide sugar, converted to disaccharides for transport, to starch for storage

Question 19

how to photosynthesis and respiration interrelate

Answer 19

both cycle oxygen/co2 in the atmosphere, products of one are the raw materials of the other

Question 20

intensity of light has to be sufficient to allow photosynthesis at a rate that replenishes….

Answer 20

carbohydrate stores used up by respiration

Question 21

plant reaches its compensation point when….

Answer 21

photosynthesis and respiration proceed at the same rate so there is no net gain/loss of carbohydrate

Question 22

compensation period

Answer 22

time it takes to reach its compensation point- different for diff species

Question 23

how do shade plants utilise light of lower intensity

Answer 23

they reach the compensation point sooner when exposed to light after being in darkness

Question 24

photosynthetic pigments

Answer 24

pigment that absorbs light of a particular wavelength and reflects other wavelengths, appearing the colour it is reflecting to our brain/eyes
the energy associated with the wavelength is funnelled down to the primary pigment reaction centre

Question 25

photosystems

Answer 25

funnel-shaped structures found within the thylakoid membranes of each chloroplast

Question 26

chlorophylls

Answer 26

a mixture of pigments- porphyrin group which is a magnesium atom + long hydrocarbon chain
e.g. chlorophyll a (P680/P700), chlorophyll b

Question 27

types of accessory pigments

Answer 27

carotenoids, xanthophylls

Question 28

where does the light-dependent stage occur

Answer 28

grana in the chloroplasts

Question 29

4 processes in the light-dependent stage

Answer 29

light harvesting at the photosystems
photolysis of water
photophosphorylation (ATP production)
formation of reduced NAD

Question 30

photosystem 1

Answer 30

pigment is a type of chlorophyll a, peak absorption of red light is 700nm

Question 31

photosystem 2

Answer 31

pigment is a type of chlorophyll a, peak absorption of red light is 680nm

Question 32

photolysis

Answer 32

when the presence of light splits water molecules into protons, electrons, oxygen with an enzyme in PSII

Question 33

non-cyclic photophosphorylation

Answer 33

involves PSI and PSII, produces ATP, oxygen, reduced NADP

Question 34

cyclic photophosphorylation

Answer 34

only PSI produces ATP but smaller quantities than non-cyclic

Question 35

where does the light-independent stage take place

Answer 35

stroma of chloroplasts

Question 36

why does the light-independent stage only run in daylight

Answer 36

products of the l-d stage are continuously needed for the Calvin cycle to run and hydrogen ions are pumped into the thylakoid spaces so conc. of free protons in stroma falls, raising pH

Question 37

role of CO2 in the light-independent stage

Answer 37

fixation of co2 in stroma maintains a concentration gradient that aids diffusion
converted to organic molecules in Calvin cycle

Question 38

limiting factor

Answer 38

when the rate of a metabolic process depends on a number of factors and is limited by the factor at its least favourable level

Question 39

factors that affect photosynthesis

Answer 39

light intensity, carbon dioxide conecentration, temperature, water stress