Chapter 17- Photosynthesis Flashcards
1
Q
How grana is adapted to its function?
A
- contains chlorophyll pigments
- contains e- carriers
- large SA for light absorption
2
Q
Why theoretical rate of photosynthesis not achieved at high light intensity?
A
- another factor becomes limiting factor
- temp becomes limiting as light independent reaction involves enzymes
3
Q
How till structure of a leaf adapted to living in shade differ from a leaf adapted to living in sunlight?
A
- larger SA
- Larger chloroplasts
4
Q
How heterotrophic organisms are dependent on plants?
A
- plants produce glucose + O2 during photosynthesis
- these used in respiration by animals
- animals eat plants to obtain organic materials
5
Q
Primary pigment?
A
Chlorophyll a
6
Q
Accessory pigment?
A
- chlorophyll b
- xanthophylls
- carotenoids
7
Q
Adv of having range of accessory pigments?
A
Can absorb different wavelengths of light
8
Q
Compound synthesis as a result of an electrical + pH gradient across thylakoid membrane?
A
ATP
9
Q
Enzyme that catalysts fixation of CO2?
A
Rubisco
Ribulose bisphosphate carboxylase
10
Q
1st stable product of carbon fixation?
A
GP
Glycerate 3 phosphate
11
Q
Compound regenerated so more CO2 can be fixed?
A
RuBP
12
Q
Polysaccharides that can be synthesised from end products of light independent stage?
A
- amylose
- cellulose
13
Q
Products of light dependent that is used in light independent?
A
ATP
NADPH
14
Q
Autotroph?
A
-can make organic molecules from inorganic molecules
15
Q
Heterotroph?
A
Feeds on + digests organic molecules that have been made by another organism
16
Q
How light is harvested in chloroplast membrane?
A
- primary + accessory pigments form a photosystem
- light energy absorbed by pigment molecules
- e- excited as move to higher energy level
- energy passed to chlorophyll a in reaction centre
- range of pigments allow range of wavelengths to be absorbed
17
Q
What would happen if movement of e- between e- carriers at PSII was blocked?
A
- prevents non cyclic phosphorylation
- no ATP + NADPH available for Calvin cycle
18
Q
What would happen if movement of e- between e- carriers at PSI was blocked?
A
- prevents cyclic + non cyclic phosphorylation
- no ATP + NADPH available for Calvin cycle
19
Q
Why herbicide can emit light + heat?
A
-energy given off from excited e-
20
Q
Why measuring CO2 uptake may or may not give better indication of photosynthesis than measuring O2 production?
A
- CO2 only used in one stage
- O2 only produced in one stage
- O2 produced may be used for respiration
21
Q
Products of light dependent stage?
A
ATP
NADPH
O2
22
Q
Graph. What happens at point that plant starts photosynthesising?
A
- is at compensation point
- rate of photosynthesis = rate of respiration
23
Q
Graph. What happens at point that rate of photosynthesis starts increasing?
A
Rate of photosynthesis greater than rate of respiration
24
Q
Function of DNA and ribosomes in chloroplasts?
A
- DNA to provide coding for protein
- ribosome for protein synthesis
- protein can be used for e- carrier
25
How to supply plant with CO2?
- dry ice
| - sodium hydrogen carbonate
26
Why not all O2 produced collected in capillary tube?
- dissolves in water
- used in respiration
- may escape collection apparatus
27
Assumptions made when carrying out practical forms measure rate of photosynthesis by measuring gas produced?
- all O2 produced by plant collected
| - all gas collected is O2
28
Why nitrogen present in gas given off by plant?
Was present in air spaces in the leaf
29
Why presence of these pigments is an advantage to seaweeds that live in deeper water?
- in dealer water there is lower light intensity
| - these pigments can absorb what little light there is
30
Fate of TP?
- regenerates RuBP so cycle can continue for further carbon fixation
- formation of glucose
- formation of amino acids, nucleic acids, lipids
31
Effect on photosynthesis of an increase in oxygen conc?
- O2 competes with CO2 for active site of Rubisco in Calvin cycle
- oxygen will be used + less CO2 fixed
32
How temp can be controlled to increase rate of photosynthesis?
- photosynthesis controlled by enzymes so increasing temp will increase rate
- heater
33
How CO2 can be controlled to increase rate of photosynthesis?
- burning paraffin
| - increases CO2 fixation
34
Why there is a difference between max rate of photosynthesis + optimum economic rate?
- maintenance of optimum temp expensive to heat or cool
| - cost of maintaining max rate would reduce profits
35
2 graphs showing rate of photosynthesis. Which is more efficient?
One which plateaus first
36
How plants can be adapted to diff light conditions?
- large no. Of chloroplasts
- large SA of leaves to absorb max light
- large no. Of stomata for max diffusion of CO2
37
Changes in rate of photosynthesis against temp?
- rate of photosynthesis increases as temp increases as enzyme controlled reactions + enzyme activity affected by temp
- plateaus at high temp as temp mo longer limiting factor. Could be CO2 conc
38
Where is energy needed in the Calvin cycle?
Conversion from GP to TP
| TP to RuBP
39
Role of rubisco
Fix carbon t RuBP
40
What proportion of TP molecules form glucose?
1 in every 6. Rest recycled to regenerate RuBP
41
Where does the CO2 come from?
Diffuses from environment
42
Why can photosynthesis not take place if light intensity too low?
Light dependent reaction cannot take place as light not reaching pigments
43
How does plant respond if CO2 too high?
Stomata close
44
How knowledge about limiting factors is useful for farmers?
Allows the to create environments with optimum conditions which increases growth + increase yield
45
Where does light dependent reaction take place?
Thylakoids
46
Where does light independent reaction take place?
Stroma
47
Function of photosystem and how PSI + PSII differ?
- absorb light energy
- absorb diff wavelengths of light
- PS2 only non cyclic photophosphorylation
- Ps1 cyclic + non cyclic
48
Photolysis?
Splitting up with light
49
What happens to e- in cyclic photophosphorylation?
- e- excited in chlorophyll are recycled back to chlorophyll molecule
- not passed to form NADPH
50
E- transport chain?
e- carrier proteins transfer e- down chain
51
Why photolysis of water essential?
- photolysis splits water into H+ e- and O2
| - e- need to be replaced in PSII
52
How e- transport chain produces ATP?
- light energy enters PSII
- e- excited + move to higher energy level
- e- move along e- transport chain
- his releases energy
- pumps H+
- chemiosmosis
- ATP synthase produces ATP from ADP + Pi
53
Enzyme needed to break down ATP + release energy?
ATPase
54
Why ATP is a good immediate energy source?
- easily broken down to release energy
- small
- soluble
- easily transported
55
Why leaves have air spaces?
Allow gases to diffuse rapidly
56
How mean cell adapted for maximum photosynthesis?
- many stomata
- many chloroplasts
- waxy cuticle
- thin + flat leaves
57
Metabolic reactions?
Series of enzyme controlled reactions
58
Function of coenzyme NADP?
- transfers H from from 1 molecule to another
| - involved in redox reactions
59
Importance of pigments in photosynthesis?
- pigments absorb light
- e- excited + raised to higher energy level
- accessory pigments pass energy to primary pigment in reaction centre
- primary pigments pass e- to e- transport chain for light dependent reaction
60
Why some need pigments that are different from those of other photosynthetic organisms?
-have to absorb light of shorter wavelengths as some wavelengths may not reach if they are in deep water
61
Process of chemiosmosis?
- occurs on thylakoid membrane
- involves e- transport chain
- e- release energy
- H+ pumped out across membrane
- proton gradient created and pH gradient
- H+ pass through hydrophilic channel protein ATP synthase
- H+ move from area of high conc to area of low concentration
- ATP synthase produces ATP from ADP + Pi
62
Why temperature has greater effect on light independent stage?
- controlled by enzymes
| - increase in temp will increase KE of enzyme molecules, increase no. Of successful collisions + no. Of ESC formed
63
Material that can be used as stationary phase in TLC?
Silica gel
64
Location of pigments in chloroplast?
Photosystems on thylakoid membrane
65
How grana are adapted to their function?
- contains pigment molecules
- contains e- carriers
- large SA for light dependent reaction
66
How will leaf of plant adapted to living in sunlight differ from leaf adapted to living in shade?
- larger chloroplasts
- more grana in chloroplast
- larger SA of leaves
67
How are heterotrophic organisms dependent on plants (autotrophs)?
- heterotrophs need to obtain organic materials from autotrophs by eating them
- plants produce glucose + o2 during photosynthesis
- organic materials used in respiration by heterotrophs
68
Polysaccharides that can be synthesised from end products of light independent stage?
- Amylose
- Amylopectin
- cellulose
69
Compound that can be made from TP?
Amino acids
70
PSII blocked. Effect?
- prevents non cyclic phosphorylation
- no e- available to produce NADPH
- ATP production by cyclic phosphorylation not prevented
71
Why plants can be seen to emit light and give off heat?
Energy given off from excited e-
72
Why measuring CO2 uptake may or may not be better than measuring O2 production?
- O2 only produced in light dependent
- O2 produced may be used for respiration
- CO2 only used in 1 stage
73
PSI blocked. Problems?
- inhibits cyclic + non cyclic photophosphorylation
| - no NADPH for Calvin Cycle
74
Role of DNA and ribosomes in chloroplast?
- protein synthesis of e- carriers
| - enzymes for Calvin Cycle
75
Role of coenzyme NADP?
- accepts H
| - supplies H to Calvin Cycle
76
How rate of photosynthesis differs during day?
- increased activity during daylight
| - as light intensity increases increased activity of light dependent stage
77
What increases temp does to chloroplasts?
- damage to chlorophyll. Reduce light dependent stage
| - damage to membranes. Reduce photophosphorylation. Reduce light dependent stage
78
Several amino acids have similar structures. Why could this be a problem when using TLC to analyse a mixture of amino acids?
-amino acids won’t separate because similar compounds have similar Rf values
79
How could you analyse chromatogram to identify amino acids?
- calculate Rf values
| - compare Rf values with those known for amino acids
80
Process that TLC separates amino acids?
Adsorption
81
Photophosphorylation?
Synthesis of ATP using energy from light
82
Effect on rate of photosynthesis if O2 come increases?
- reduces rate
- less rubisco available for CO2 as more o2 competing with CO2 for rubisco
- less carbon fixation
83
Why presence of these pigments is an advantage to seaweeds that live deep under water?
- in deeper water there is a lower light intensity
- these pigments can absorb what little light there is
- mainly shorter wavelenghts of light that penetrate
- these pigments can absorb pigments of that wavelength
84
do sieve tube elements have chloroplasts?
yes`
