photosynthesis

Question 1

where do light dependent reactions take place

Answer 1

on thylakoid membrane of chloroplast

Question 2

where do light independent reactions take place

Answer 2

in stroma of chloroplast

Question 3

draw and label a chloroplast

Answer 3

starch granule
ribosome
nucleoid
stroma
grana
granum
lamellae
thylakoid
chloroplast envelope

Question 4

what are the stages of light dependent reactions

Answer 4

photoionisation
production of ATP and reduced NADP
chemiomosis
photolysis

Question 5

what is photoionisation in LDR

Answer 5

chlorophyll absorbs light which excites electrons to a higher energy level releasing them from the chlorophyll

Question 6

how is ATP and reduced NADP made briefly in LDR

Answer 6

some energy from electrons being released during photoionisation is ued to create ATP and NADP

Question 7

what is made in chemiosmosis in LDR

Answer 7

ADP

Question 8

how is ADP made in LDR in chemiosmosis

Answer 8

1. elecrons pass down electron transfer chain via redox reactions losing energy at each step
2. this energy is used ti actively transport protons from stroma to thylakoid
3. creates a proton/ electrochemical gradient across thylakoid membrane
4. protons move by facilitated diffusion down electrochemical gradient into stroma via enzyme ATP synthase embedded in thylakoid membrane
5. energy from this allows ADP + Pi –> ATP

Question 9

how is reduced NADP made in chemiosmosis in LDR

Answer 9

protons from photolysis join with co-enzyme NADP and becomes reduced NADP
protons move from high conc. to low conc.

Question 10

what is phoyolysis in LDR

Answer 10

splitting of water using light energy
produces protons, electrons and oxygen
electrons replace those lost from chlorophyll

Question 11

what are the products of thr LDR

Answer 11

ATP- used in LIR
reduced NADP - used in LIR
oxygen - leaves cell as a by product or used in respiration

Question 12

draw calvin cycle

Answer 12

CO2 (1C)
——————rubisco—> 2x glycerate 3-phosphate ———ATP ->ADP + Pi — reduced NADP -> NADP ————> 2x triose phosphate (3C)———-
useful organic products
————- ATP -> ADP +Pi —————- ribulose bisphosphate(5C) —————

Question 13

explain the calvin cycle

Answer 13

CO2 reacts with RuBP catalysed by enzyme rubisco —> produced 2 molecules of glycerate 3-posphate ——–> GP reduces to triose phosphate using products from LDR: energy from hydrolysis of ATP and H+ from reduced NADP ——> some TP converted into useful organic products eg. glucose —> TP used yo regenerate RuBP using rest of ATP

Question 14

what is a limiting factor in photosynthesis

Answer 14

rate of photsynthesis increases untill photsynthesis is limited by a different factor

Question 15

how does increasing temperature affect rate of photosynthesis

Answer 15

increases up to optimum then decreases
limits light independent as enzyme controlled (rubisco)
more kinetic energy, more E-S complexes
above optimum H bond in tertiary structure break, active site changes shape, fewer E-S complexes

Question 16

how does increasing light intensity affect the rate of photosynthesis

Answer 16

increases rate until limiting
if light levels dramatically reduced
- levels of ATP and reduced NADP fall as LDR limited as less photoionisation of chlorophyll
- GP cant be reduced to TP ( required ATP and reduced NADP)
- TP cant regenerate RuBP (requires ATP)

Question 17

how des increasing carbon dioxide concentration affect rate of photsynthesis

Answer 17

rate increases iuntil limiting
if CO2 conc. dramatically reeduced
- limits LIR
- less CO2 to combine with RuBP to form GP
- less GP reduced to TP
- less TP converted to organic substances and used to regenrate RuBP

Question 18

what are some common agricultural practices to overcome limiting factors

Answer 18

artificial lighting
heating a greenhouse
burning fuel

Question 19

what does the use of commom acrigultural practices lead to for farmer

Answer 19

faster prodiction of glucose allowing faster respiration

more ATP to provide energy for growth eg. cell division and protein synthesis

higher yield so more profit