photosynthesis

Question 1

what are the adaptions of leaves for photosynthesis?

Answer 1

large surface area
thin
permeable
cuticle and epidermis are transparent

Question 2

what are the adaptions of palisade cells?

Answer 2

large vacuole
cylindrical elongated cells
large number of chloroplasts

Question 3

why are plants green?

Answer 3

photosynthetic pigments in thylakoid membranes of chloroplasts

Question 4

what do chloroplasts do?

Answer 4

absorb light energy and convert it into chemical energy

Question 5

how are chloroplasts adapted to photosynthesis?

Answer 5

stacking of thylakoids allows maximum light catchment
outer membrane keeps enzymes in chloroplasts
thylakoid membrane contains photosynthetic pigments
stroma fluid contains enzymes for photosynthesis

Question 6

what is the role of the stroma?

Answer 6

site of light independent reactions

Question 7

what is the role of the thylakoid?

Answer 7

site of light dependent reactions

Question 8

what are the different types of pigments?

Answer 8

chlorophyll a and b
carotenoids

Question 9

what is chromotography?

Answer 9

separation technique used to separate pigments in plant leaves

Question 10

what is Rf value?

Answer 10

shows how far a component has travelled compared to solvent font
distance moved by component / distance moved by solvent

Question 11

what does absorbance spectra show?

Answer 11

degree of absorption of different wavelengths by light by an individual pigment

Question 12

what lights do chlorophylls absorb strongly in?

Answer 12

violet, blue and red

Question 13

what lights do carotenoids absorb strongly in?

Answer 13

blue and green

Question 14

what does action spectra show?

Answer 14

degree to which different wavelengths of light affect rate of photosynthesis

Question 15

what is photosynthesis?

Answer 15

process by which autotrophic organisms use light energy to make sugar and oxygen from carbon dioxide and water

Question 16

what happens in light dependent stage (basic)?

Answer 16

converts solar energy to chemical energy
produces ATP, oxygen and reduced NADP

Question 17

what happens in light independent stage (basic)?

Answer 17

makes glucose from oxygen
ATP provides energy for sugar synthesis
NADPH provides energy for reduction of CO2 to glucose

Question 18

what happens in the first stage of photosynthesis?

Answer 18

photoexcitation
energy from sunlight causes electrons from chlorophyll to become excited

Question 19

where are photosystems and what do they do?

Answer 19

in plane of thylakoid membrane
collect accessory pigments which absorb light and transmits energy to reaction centre

Question 20

what is in the antenna complex?

Answer 20

array of pigment molecules in phospholipids of thylakoid membrane

Question 21

what is in the reaction centre?

Answer 21

contains 2 molecules of primary pigment chlorophyll a
absorbs light, excites electrons, emits electrons

Question 22

what is in PSI?

Answer 22

absorption peak of 700nm

Question 23

what is in PSII?

Answer 23

absorption peak of 680nm

Question 24

what is the second stage of photosynthesis?

Answer 24

photophosphorylation

Question 25

what happens in cyclic photophosphorylation?

Answer 25

only PSI photons of light absorbed by pigments in antenna complex 2 electrons in reaction centre are excited (photoactivation) electrons emitted and received by electron acceptor 2 electrons pass down electron transport chain generates sufficient energy to synthesis ATP by chemiosmosis H+ is pumped into lumen by proton pump then diffuse out through ATP synthase to produce ATP electrons return to reaction centre of PSI NO reduced NADP produced

Question 26

what happens in non-cyclic photophosphorylation?

Answer 26

photons of light absorbed by PSII 2 electrons excited and picked up by electron acceptors 2 electrons passed down electron transport chain then passed onto PSI energy produced to pump H+ ions into lumen to create gradient protons then flow through ATP synthase to form ATP PSII left with positive charge receives electrons from photolysis of water PSI gets photoactivated at same time as PSII excited electrons passed down electron transport chain generating ATP electron acceptors pass the 2 electrons to hydrogen ions where they reduce NADP

Question 27

what is the passage of protons during photophosphorylation?

Answer 27

energy from 2 electrons along transport chain is used to pump H+ from stroma into thylakoid membrane protons accumulate in thylakoid membrane creates electrochemical gradient (also due to photolysis) H+ flow back into stroma through ATP synthase to synthesis ATP in stroma, H+ ions combine with NADP to produce NADPH

Question 28

what happens during the light independent stage?

Answer 28

CO2 in stroma combines with 5C compound to produce RuBP catalysed by RuBISCO product is unstable 6C breaks down into 2 molecules of 3C compound GP ATP and NADPH provide reducing power to convert GP into TP TP either converted to glucose phosphate then starch or regenerated back to RuBP

Question 29

how are carbohydrates produced from light independent reaction?

Answer 29

produce fructose phosphate then converted into glucose then sucrose alpha glucose converted into starch beta glucose converted into cellulose

Question 30

how are fats produced from light independent reaction?

Answer 30

GP used for synthesis of acetyl coA TP converted to glycerol glycerol and fatty acids condensed into triglycerides

Question 31

how are proteins produced from light independent reaction?

Answer 31

GP converted to amino acids for protein synthesis

Question 32

what happens during engelmann's experiment?

Answer 32

determines which wavelengths of light are most effective spiral chloroplasts of algae photosynthesise oxygen gas produced motile aerobic bacteria exposed to various wavelengths of light bacteria move towards parts of chloroplasts exposed to red and blue parts of spectrum

Question 33

what is a transducer?

Answer 33

changes energy from one form into another e.g. chloroplasts

Question 34

factors affecting photosynthesis?

Answer 34

magnesium concentration nitrogen concentration CO2 concentration light intensity humidity temperature