Photosynthesis 5.6

Question 1

structure of the chloroplast

Answer 1

. outer membrane
. inner membrane
. thylakoid
. thylakoid membrane
. granum
. thylakoid space
. stroma
. lamellae

Question 2

what are granum made of

Answer 2

stacks of thylakoids

Question 3

what does the stroma contain and function

Answer 3

starch granule, enzymes, proteins, ribosomes, and chloroplast DNA - for LIDS

Question 4

what does the thylakoid space contain and function

Answer 4

chlorophyll - absorbs light used in the LDS

Question 5

what are photosynthetic pigments also known as?

Answer 5

harvesting systems or reaction centers

Question 6

describe photosynthetic pigments

Answer 6

• arranged in photo systems that absorb light
• 2 types PSI and PSII

Question 7

difference between PSI and PSII

Answer 7

• contains chlorophyll that absorbs light at 700 nm
• contains chlorophyll that absorbs light at 680 nm

Question 8

what is a primary pigment and an accessory pigment?

Answer 8

• chlorophyll A
• not involved in the LDR but helps channel more light energy into chlorophyll to excite more e-

Question 9

describe what occurs in the light dependent reaction / cyclic

Answer 9

1. light hits chlorophyll in leaf which excites the e-
2. causes them to move to a higher energy level
3. e- move down ETC from PSII to PSI
4. lost e- in PSII replaced by H+ from the photolysis of water - O2 as a waste product
5. H+ pumped into thylakoid space from stroma due to a proton gradient
6. H+ diffuse back into stroma via ATP synthase down a conc. gradient
7. ATP synthase produces ATP from ADP + Pi
8. e- and H+ taken up by NADP to form reduced NADP

Question 10

products of the LDS

Answer 10

reduced NADP and ATP

Question 11

describe the non-cyclic stage

Answer 11

. only uses PSI
. e- not passed onto NADP but back to PSI via e- carriers
. e- are recycled and constantly flow back to PSI
. doesnt produced reduced NADP but small amounts of ATP

Question 12

describe the light independent stage / calvin cycle

Answer 12

Carboxylation
. CO2 combines with RuBP from a 6C compound using enzyme RuBisCO
. 6C compund is unstable so splits into 2 mol. of GP

Reduction
. 2 reduced NADP donates H+ to reduce 2x GP to 2x TP
. 2 ATP used for the molecular rearrangement of GP into TP

Regeneration
. 5/6 mol. of TP used to regenerate RuBP
. 1/6 mol. used to form organic compounds like glucose

Question 13

how many turns should the Calvin Cycle take to form one mol. of glucose

Answer 13

Glucose = 6C
3 turns of cycle = 6TP , 5 used for RuBP, 1 for Glucose
must turn 6 times = 12 TP , 10 for RuBP , 2 for glucose
1 TP contains 3C , 2 contains 6C

Question 14

products of the calvin cycle

Answer 14

NADP
ADP + Pi
TP
RuBP

Question 15

what other useful substances do TP and GP create

Answer 15

carbs from 2TP mol.

lipids from TP and GP

Amino acids from 2GP

Question 16

factors that affect photosynthesis

Answer 16

1. Light intensity and Wavelength
2. Temp
3. CO2 levels
4. Water availability

Question 17

how does light intensity affect photosynthesis

Answer 17

. high LI means e- have more energy in excited state
. but at very high LI, chlorophyll becomes damaged
. at low LI , GP not converted into TP so accumulates
. TP lvls fall and RuBP lvls because its not being regenerated
. ROP decreases

Question 18

how does temp affect photosynthesis

Answer 18

. relies on enzymes
. low temp = enzymes work slowly
. too high = becomes denatured

. above 30 degrees, enzyme RuBisCo has an active site for both O2 and CO2
. O2 is a competitive inhibitor so less CO2 is accepted by RuBP
. less GP made so RuBP accumulates bcs of no TP
. ROP decreases

Question 19

how does CO2 levels affect photosynthesis

Answer 19

. normal CO2 levels in atmosphere = 0.04%
. plants work best at 0.40%

. above 0.40, stomata close so CO2 = LF
. if CO2 lvls are lower than 0.01, then RubP cant accept it so accumulates, GP not made and TP aswell
. ROP decreases

Question 20

how does water availability affect photosynthesis

Answer 20

. plants need alot of water but too much means roots become waterlogged and cant respire
. less ATP made so leads to chlorosis ( yellow leaves )
. ROP decreases

Question 21

how do farmers optimise conditions to improve growth

Answer 21

. use LED lamps : blue and red wavelengths to inc the light intensity
. Fans to control temp
. CO2 generators to increase CO2 lvls
. Glasshouse - traps heat and makes air warm

Question 22

relationship between photosynthesis and respiration

Answer 22

photosynthesis produces O2 and Glucose needed fore respiration

respiration produces water and CO2 needed for photosynthesis