Ch11 Photosynthesis

Question 1

5 ways chloroplasts are adapted to photosynthesis

Answer 1

1. thylakoid membranes provide large SA for light absorption
2. permeable membrane allows diffusion of gases
3. membranes provide surface for attachment pf electrons
4. stroma contain enzymes for calvin cycle

Question 2

5 ways leaf is adapted to photosynthesis

Answer 2

1. thin- short diffusion pathway
2. transparent cuticle and epidermis to let light through
3. long narrow upper mesophyll(full of chloroplasts)
4. air spaces in lower spongy mesophyll for rapid gas diffusion
5. large SA to collect light energy
6. stomata to allow exchange of gases
7. xylem for input of water
8. phloem for removal of end products

Question 3

Site of light dependent reaction

Answer 3

thylakoids

Question 4

Site of light independent reaction

Answer 4

stroma
(fluid-like matrix)

Question 5

lamellae

Answer 5

tubular extensions that join up adjacent grana

Question 6

overall equation

Answer 6

6CO2 + 6H2O -> C6H12O6 + 6O2

Question 7

3 main stages

Answer 7

1. capturing light energy in chloroplast pigments
2. light dependent reaction
3. light independent reaction

Question 8

4 stages of light dependent reaction

Answer 8

1. photoionisation
2. photolysis
3. chemiosmosis
4. production of ATP and NADP

Question 9

Photoionisation

Answer 9

1. light absorbed by chlorophyll
2. electrons become excited
3. pass down chain of carriers in oxidation-reduction reactions 4. releasing energy

Question 10

Photolysis equation

Answer 10

2H2O -> O2 + 4e- + 4H+

Question 11

Photolysis

Answer 11

Light splits water
supplies protons and electrons
Pass out of thylakoid into ATP synthase channel
Reduces NADP
Oxygen is used in respiration

Question 12

Chemiosmosis

Answer 12

Energy released from transfer electron transfer chain
Used to bond ADP and inorganic phosphate to form ATP (photosphosphorylation)

Question 13

Light independent reaction (calvin cycle)

Answer 13

1. Co2 reacts with ribulose biphosphate (with enzyme rubisco)
2. produces two glycerate 3-phosphate molecules
3. GP reduced to triose phosphate 4. using reduced NADP
4. using energy from ATP
5. triose phosphate converted to organic substances( glucose, hexose, carbohydrates, starch ect)
6. RuBP regenerated

Question 14

Site of light independent reaction

Answer 14

Stroma

Question 15

What happens when its dark

Answer 15

1. Stomata closed so no CO2 for LIR
2. No photolysis occurs
3. No electrons excited so less energy produced
4. No ATP is produced
5. No NADP reduced
6. GP can’t be converted
7. TP not formed

Question 16

Similarities between photosynthesis and respiration

Answer 16

1. both use and produce ATP
2. have chain of electron carries
3. involve cycle of reaction
4. process controlled by enzymes
5. locates on membranes
6. involves oxidation and reduction

Question 17

Increase in temperature on rate

Answer 17

1. Enzyme involved
2. Kinetic energy increases
3. Molecules have more successful collisions
4. more enzyme-substrate complex form so rate increases
5. Can denature so LIR can’t take place

Question 18

Limiting reagents

Answer 18

1. light intensity
2. availability of water
3. temperature
4. CO2 concentration

Question 19

Photosynthesis extension points

Answer 19

1. Photosynthetic life forms turn 100-115 million tons of carbon into biomass per year

2.Photosynthetic phytoplankton in the seas produces 70% of the world’s oxygen

3. Land-based photosynthetic life produces only 30% of the world’s oxygen