c1.2 - photosynthesis

Question 1

chloroplast

Answer 1

organelle found in plants + green algae
site of photosynthesis

Question 2

structure of chloroplast

Answer 2

double membrane
grana - stacks of flattened disks (thylakoid) contains ps1 + ps2, ETC, atp synthase
grana connected by intergranal lamellae
stroma
- fluid filled matrix contains enzymes

Question 3

where are chloroplasts located in angiosperm leaf

Answer 3

mainly in palisade layer

Question 4

chloroplast adaptations for photosynethis

Answer 4

• thylakoids give large SA for light independent reactions
• photosynthetic pigments affra ged in photosys5ems to maximise light absorption
• stroma directly surrounds grana = products of photosynthesis diffuse directly into stroma
• contain DNA + ribosomes
  inner membrane less permeable than outer, enabling control over movement of substances

Question 5

angiosperm leaf adaptations for photosynthesis

Answer 5

• large SA to maximise light absorption
• think to reduce diffusion distance for co2
• upper epidermis transparent allowing light to strike mesophyll layers
• palisade cells densely packed + contain many chloroplasts
• air spaces reduce diffusion distance for co2
• vein network transports water + minerals to lead to+ takes sugars away
• stomata allow co2 to diffuse into leaf

Question 6

transducer, why are chloroplasts described as transducers

Answer 6

• something converts one type of energy into another
• transduce light energy into chem energy of ATP

Question 7

photosynthetic pigment

Answer 7

molecule present in chloroplasts that absorb light energy for photosynthesis
absorbs specific light wavelengths c reflects ithers

Question 8

examples of photosynthetic pigments

Answer 8

• chlorophyll a+b
• carotenoids
• xanthophylls

Question 9

why range of photosynthetic pigments

Answer 9

absorbs range of light wavelengths

Question 10

purpose of chromatography

Answer 10

separates different products from a mixture of

Question 11

equation used to calculate Rf

Answer 11

distance travelled by component
Rf = ————————————————
distance traveled by solvent

Question 12

photosynthesis

Answer 12

complex metabolic pathway that synthesises organic molecules from co2 + water in presence of light
6CO2 + 6H2O -> C6H12O6 + 6O2

Question 13

stages of photosynthesis

Answer 13

light dependent
light independent

Question 14

photosystem

Answer 14

• protein complex consisting of antennae complex + reaction centre
• involved in absorption of light + transfer of electrons in photosynthesis
• two types: ps1 + ps2

Question 15

difference between ps1 + ps2

Answer 15

absorb different light wavelengths

Question 16

process of light harvesting

Answer 16

• antennae complex absorbs light energy of varying wavelengths + transfers it quickly and efficiently to reaction centre
• energy absorbed by two chlorophyll a molecules which emit excited electrons

Question 17

absorption spectrum

Answer 17

pattern of bands that occurs when a substance absorbs different wavelengths of light

Question 18

action spectrum

Answer 18

graph of rate of photosynthesis against each light absorbed by a pigment

Question 19

light dependent stage

Answer 19

• first stage of photosynthesis
• takes place in thylakoids of chloroplast
• uses light energy t9 produces ATO, reduced NADP, and O2

Question 20

sources of electrons for ETC

Answer 20

cyclic + non-cyclic photophosphorylation

Question 21

cyclic photophosphorylation

Answer 21

formation of ATP involving ps1 only, where NADP is not reduced

Question 22

outline cyclic photophosphorylation

Answer 22

• involves ps1 only
• excited electrons enter ETC.to produce ATP then return to ps1
• no reduction of NADP + no water required to replace lost electrons

Question 23

purpose of cyclic photophosphorylation

Answer 23

produces additional ATP to meet surplus energy demands of cell

Question 24

non cyclic photophosphorylation

Answer 24

formation of ATP + reduced NADP involving ps1 and ps2

Question 25

outline non cyclic photophosphorylation

Answer 25

- involves ps1 + ps2 - excited electrons nested ETC to produce ATP - NADP acts as final electron acceptor + is reduced - water is photolysed to compensate for electrons lost for ps2

Question 26

purpose of non cyclic photophosphorylation

Answer 26

produces ATP + reduced NADP for calvin cycle

Question 27

how does chemiosmosis produce ATP in lds

Answer 27

- protons flow down conc gradient from thylakoid space into stroma via ATP synthase - ATP synthase phosphorylates ADP to form ATP as protons flow through it

Question 28

photolysis

Answer 28

splitting of molecule of water in presence of light that occurs in lds produces protons, electrons, and o2 H2O -> 2H+ + 2e- + 1/2O2

Question 29

what happens to products of photolysis

Answer 29

H+ - used in proton pumping and to reduce NADP e- - replace electrons lost from chlorophyll a in ps2 O2 - byproduct, used for respiration or diffuses out of leaf as waste gas

Question 30

how ETC results in production of reduced NADP

Answer 30

NADP acts as final electron acceptor subsequently reduced

Question 31

LIS of photosynthesis

Answer 31

- second stage of photosynthesis - calvin cycle produces glucose - doesn’t require light energy + takes place in stroma - uses CO2 + products of LDS to build organic. ole uses

Question 32

what is LIS also known as

Answer 32

calvin cycle

Question 33

main stages of calvin cycle

Answer 33

- carbon fixation - reduction - regeneration

Question 34

carbon fixation of calvin cycle

Answer 34

- reaction between CO2 + RuBP catalysed by enzyme RuBisCo - forms unstable 6C intermediate that breaks down into 2 molecules of G3P

Question 35

reduction of calvin cycle

Answer 35

- 2 G3P reduced to 2 TP - requires 2 reduced NADP + 2 ATP formed during LDS - forms 2 NADP + 2 ADP that enter LDS

Question 36

regeneration of calvin cycle

Answer 36

- after 1C leaves cycle, 5C compound forms - RuBP regenerated from 5C usuing 1 ATP - forms 1 ADP

Question 37

how are nutrients produced as a result of photosynthesis

Answer 37

- formation of amino acids for GP (requires nitrates + sulfates) - TP molecules used to produce sugars e.g: glucose, fructose, sucrose

Question 38

limiting factor

Answer 38

variable that limits rate of reaction

Question 39

limiting factors in photosynthesis, what stage limited

Answer 39

light intensity - LDS light wavelength- absorption by chlorophyll CO2 concentration - LIS temp - enzyme controlled reactions (carbon fixation) pH - enzyme controlled reactions

Question 40

role of nitrogen in plant metabolism

Answer 40

synthesis of amino acids, nucleotides, + chlorophyll

Question 41

what does nitrogen deficiency in plants cause

Answer 41

- stunted growth - chlorosis (yellowing of leaves due to insufficient chlorophyll production)

Question 42

role of magnesium in plant metabolism

Answer 42

central component of chlorophyll

Question 43

what does magnesium deficiency in plants cause

Answer 43

chlorosis (yellowing of leaves due to insufficient chlorophyll production)