Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

bio > Photosynthesis > Flashcards

Photosynthesis Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What are the two forms of nutrition ?

A

1 autotrophic nutrition
2 heterotrophic nutrition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is autotrophic nutrition ?

A

Making organic molecules from inorganic raw material obtained from the environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the two types of autotrophs ?

A

1 photoautotrophs - energy source is light
2 chemo-autotrophs - energy source is chemicals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is heterotrophic nutrition ?

A

Organisms that cannot manufacture their own food

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the equation of photosynthesis ?

A

6 CO2 + 12 H2O + light energy —chlorophyll—> C6H12O6 + 6 H2O + 6 O2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the two stages of photosynthesis ? Where do they occur ?

A

Light-dependent stage : thylakoid membranes of chloroplast

Light-independent stage : chloroplast stroma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where are chloroplast found ?

A

Mainly in mesophyll tissue of the leaf

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are some structures of chloroplast ?

A
  • double membrane
  • stroma
  • thylakoid membrane
  • granum
  • thylakoids
  • Intergranal lamellae
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Description of the chloroplast envelope ?

A

double membrane
outer membrane highly permeable
inner membrane less permeable with imbedded transport proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Function of chloroplast envelope

A
  • allows compartmentalisation and specialisation by enclosing reactant and enzyme involved in photosynthesis together, creates optimal environment for enzymes to function
  • special transport proteins in the inner membrane allows regulation of substances moving in and out of chloroplast
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the lamellae system made up of?

A

Thylakoids - a flattened disc like sac enclosing a fluid filled thylakoid space, stacked together to form grana
Intergranal lamellae - sheet like pairs of membranes that connects grana

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the functions of the lamellae system ?

A
  • provides large SA ador attachment of photosynthetic pigments, electrons carriers and ATP synthase : allows for maximum absorption of light, ETC closely located and spatially arranged for transfer of electrons
  • compartmentalisation of thylakoid space : allows setting up of proton gradient for ATP synthesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Description of stroma

A

Dense like fluid matrix
Contains : circular DNA, RNA, 70s ribosomes, enzymes, starch grains, lipid droplets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Function of stroma ?

A
  • surrounds lamellae system : products of light dependent stage enter Calvin cycle in stroma
  • large area for temporary storage of sugars and starch
  • DNA codes for some chloroplast proteins, synthesised by chloroplast enzymes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the function of photosynthetic pigment ?

A

To absorb light energy, thereby converting it to chemical energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where is photosynthetic pigment located in a plant ?

A

On thylakoid membranes of chloroplast - usually arranged so that the thylakoid membranes are at the right angles to the light source for maximum absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the two classes of photosynthetic pigments ( in higher plants ) ?

A

Chlorophyll
Carotenoids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What light does chlorophyll absorb ?

A

Mainly red and blue-violet light
Reflects green light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which photosynthetic pigment is the most abundant ? Why ?

A

Chlorophyll a
Due to its central role as primary pigment - the only pigment that directly converts solar energy to chemical energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the function of chlorophyll b?

A

Accessory pigment
Absorbs slightly different wavelengths of light and transfer the energy to chlorophyll a

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the five structures of chlorophyll related to its function ?

A
  1. Long tail is hydrophobic - allows it to be embedded within the phospholipid bilayer of thylakoid membrane
  2. Head is hydrophilic - allows it to lie at the surface of thylakoid membrane next to the aqueous stroma
  3. Flat head of chlorophyll molecule lies parallel to membrane surface - maximum light absorption
  4. Absorption of light by head causes emission of electrons - necessary for initiation of light dependent reaction
  5. Modification of side groups on the head causes changes to absorption spectrum - diff energies of light absorbed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What light does carotenoid absorbs ? Colour reflected ?

A

Blue-violet
Reflectes a range of colours, yellow, red, orange, brown but often masked by green chlorophyll

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the function of carotenoids ?

A

Accessory pigment and helps absorbs wavelengths of light that chlorophyll a cannot, helps broaden the spectrum of colours that drive photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is a spectrophotometer?

A

Instrument that measures the ability of a pigments to absorb various wavelengths of light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is an absorption spectrum ?

A

Graph depicting the amount of light absorbed by a pigment at different wavelengths of light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is an action spectrum ?

A

Record of the rate of photosynthesis occurring at different wavelengths of light
It shows the efficient of different wavelengths of light in photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the three main reactions of the light dependent stage ?

A

1 photo-activation of water
2 photolysis of water
3 generation of ATP and reduced NADP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the main purpose of light dependent reactions ?

A

To convert light energy to chemical energy (ATP and red NADP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are photosystems ?

A

Light harvesting clustered arranged at the thylakoid membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are the two types of photosystems ?

A

Photosystem I (PSI)
Photosystem II (PSII)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are the three components that make up a Photosystem ?

A

1 light harvesting antenna complex
2 reaction Center
3 primary electron acceptor

32
Q

What is the function of the light harvesting antena complex photosystems ?

A

Absorb light, transfer energy from molecule to molecule until it reaches specialised chl a at the centre

33
Q

What is the reaction centre of Photosystem ?

A

Pair of specialised chl a molecules which trigger light reaction by donating their excited electron to a primary electron acceptor which traps high-energy electrons and passes them to ETC

34
Q

What’s the difference between PSI and PSII ?

A

PSI - reaction centre pigments is P700, absorbs light best at 700nm
PSII - reaction centre pigment is P680, absorbs light best at 680nm

Both have light harvesting antenna complex and primary electron acceptor

35
Q

What are the advantages of have light harvesting antenna ?

A
  • increase the range of light the Photosystem can absorb
  • increase amount of light energy the Photosystem can absorb
36
Q

Which Photosystem occurs first ?

A

BOTH OCCUR TOGETHER !!

37
Q

What are the two routes that electrons can take to leave the Photosystem ?

A

Cyclic and non-cyclic

38
Q

What are the six general steps of non-cyclic phosphorylation ?

A
  1. Photo activation (PSII)
  2. Photolysis of water (PSII)
  3. Excited electrons (PSII)
  4. Chemiosmosis - ATP
  5. Excited electrons (PSI)
  6. Final electron acceptor - NADP
39
Q

What occurs in photo activation in non-cyclic phosphorylation?

A

Electrons of P680 of PSII are excited by light energy and donated to the primary electron acceptor : chlorophyll molecule has been photo activated

40
Q

What occurs in photolysis of water in non-cyclic phosphorylation?

A

H2O is split to release electrons to replace the donated electrons producing O2

41
Q

How is ATP produced in non-cyclic phosphorylation?

A

Excited electrons from PSII are passed along the electron carriers in ETC in the thylakoid membrane, energy released is harnessed to produce ATP through chemiosmosis

Excited electrons from PSI are passed along another ETC to produce ATP

42
Q

How are electrons replaced in PSI of non-cyclic phosphorylation?

A

Electrons that were passed along the ETC enter PSI and replace the electrons that are lost from P700 as a result of absorption of light

43
Q

How is reduced NADP produced in non-cyclic phosphorylation?

A

Electrons are passed from the ETC after PSI to the final electron acceptor, NADP+ to produce reduce NADP

44
Q

What are the photochemical products of the light dependent stage ?

A

ATP
reduced NADP

45
Q

Which Photosystem is involved in cyclic phosphorylation?

A

Only PSI

46
Q

What are the products of cyclic phosphorylation ?

A

Only ATP

47
Q

What occurs in cyclic phosphorylation?

A

Absorption of light energy in light harvesting antenna complex leads to excitation nod displacement of electrons from P700 in reaction centre of PSI
Excited electrons are returned to P700 via ETC instead of being taken up by NADP

48
Q

How is a steep proton gradient formed across the thylakoid membrane for chemiosmosis to occur to produce ATP ?

A

Protons are generated from the photolysis of water in the thylakoid space
More protons are pumped (through proton pumps by active transport) into thylakoid space from stroma by energy produced from electrons carriers of successively lower energy level in the ETC

49
Q

How is ATP produced through chemiosmosis ?

A

Steep proton gradient generates proton motive force that allows ATP synthase to phosphorylate ADP to ATP as protons diffuse down steep gradient from thylakoid space into stroma

50
Q

What does the Calvin cycle / light-independent reactions do?

A

Synthesis carbohydrates from carbon dioxide, requires ATP and reduced NADP produced in light dependent reactions

51
Q

Where does the Calvin cycle occur?

A

Stroma

52
Q

What are the three phases of Calvin cycle ?

A
  1. Carbon fixation
  2. PGA / carbon reduction
  3. RuBP regeneration
53
Q

What occurs during carbon fixation of the Calvin cycle ?

A

Carbon dioxide combines with ribulose biphosphate (RuBP), a 5 carbon sugar - reaction catalysed by RuBP carboxylase aka rubisco
Product is a unstable 6C compound which splits to form 2 molecules of 3-phosphoglycerate (PGA)

54
Q

What occurs in PGA reduction of the Calvin cycle ?

A

PGA is reduced by red NADP to form triose phosphate (TP) - energy in form of ATP required

55
Q

What is TP used for ?

A

Two TP linked together forms glucose phosphate
Starch is formed by condensation of many glucose phosphate molecules

56
Q

What occurs in RuBP regeneration of the Calvin cycle ?

A

For every 6 TP (3C) produced, only 1 exits the cycle to be used by the plant to synthesis glucose, the other 5 are recycled to regenerate RuBP (5C) - chemical energy in form of ATP needed
5 cycles regenerates 3 RuBP

57
Q

Why does RuBP molecules need to be regenerated ?

A

For carbon fixation to continue, RuBP molecules that have been used have to be replaced

58
Q

What are the three factors that can limit rate of photosynthesis ?

A

Light intensity
Carbon dioxide concentration
Temperature

59
Q

How does low light intensity affect photosynthesis ?

A

Shortage of photochemical products of the light independent reactions (ATP and reduced NADP), PGA cannot be reduced

60
Q

What is the light saturation point ?

A

Point where any further increase of light intensity does not affect rate of photosynthesis, another factor has become limiting

61
Q

How is rate of photosynthesis measured ?

A

Amount of CO2 absorbed or amount of O2 evolved

62
Q

What is the light compensation point ?

A

Light intensity which the rate of photosynthesis is equal to the rate of respiration, all CO2 produced during respiration exactly balances that being used in photosynthesis

63
Q

What occurs below light compensation point ?

A

At light intensities below light compensation, rate of respiration is higher than rate of photosynthesis - plant is using its reserves and will die if reserves are used up

For a plant to grow, light intensity must be above compensation point

64
Q

What does having a lower light compensation point mean ?

A

Lower light compensation = able to maintain positive rate of photosynthesis at lower light levels = growth

65
Q

What is the major limiting factor of photosynthesis?

A

Carbon dioxide concentration
Normally low concentration in atmosphere of 0.04%, optimal concentration is 0.1%

66
Q

How does carbon dioxide concentration limit photosynthesis?

A

In Calvin cycle CO2 cannot be used to form PGA, RuBP and reduced NADP accumulated

67
Q

Does temperature affect both light dependent and light independent (Calvin cycle) of photosynthesis ?

A

Only affects Calvin Cycle (enz are involved)

68
Q

How does Low temperatures affect photosynthesis?

A

Enzymes that catalyse reactions of Calvin cycle work slowly, reduced NADP accumulates

69
Q

How much does rate of photosynthesis increases with an increase in temperature ?

A

Rate doubles for every 10C increase up to optimum temperature

70
Q

How does temperatures above optimum affect rate of photosynthesis?

A

Enzymes denature, rate of photosynthesis falls

71
Q

What is the minimum temperate which photosynthesis can occur ?

A

0 degrees for most plants

72
Q

What are some other factors that affect rate of photosynthesis?

A

Water
Oxygen concentration
Chlorophyll concentration

73
Q

How does water deficiency affect rate of photosynthesis?

A

If wilting is induced and stomata of the plant is closed, decreased entry of CO2 = CO2 concentration limiting

Photolysis of water reduced, photosynthesis reduced

74
Q

How does high levels of O2 affect rate of photosynthesis?

A

O2 is competitive inhibitor of Rubisco, competes with CO2 for active site of Rubisco which catalyses fixation of CO2 with RuBP during Calvin cycle

75
Q

How does chlorophyll concentration affect rate of photosynthesis?

A

Decreased chlorophyll = less light for photosynthesis

bio (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions