Photosynthesis Flashcards

1
Q

Purpose of photosynthesis

A

to convert solar energy into glucose (chemical energy)

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2
Q

What does photosynthesis occur in?

A

plants, algae & other protists, cyanobacteria and some prokaryotes

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3
Q

Photosynthesis chemical equation

A

6CO2+6H2O+Light energy–> C6H12O6+6O2

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4
Q

List the level of organiztion in plants:

A

Leaf-Mesophyll-Chloroplast-Thylakoid-Chlorophyll

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5
Q

Define the cuticle

A

waxy covering that protects the leaf from excess water loss

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6
Q

Define the upper epidermis

A

outer layer of cells for protection

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7
Q

Define the palisade mesophyll

A

light collection by closely packed rows of palisade mesophyl (2 rows may be in present in plants adapted to low light)

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8
Q

Define the spongy mesophyll

A

adapted gas exchange–> loosely packed fewer chloroplasts than palisade cels, and have intercellular air spaces where gases collect & mix - they do less photosynthesis

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9
Q

define the function of guard cells

A

controls the amount of water and air entering and exiting the leaf , when guard cell fills with water stoma closes

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10
Q

Define stoma

A

small openings in the underside of the leaf that allow entry of gases–> when guard cells fill with water= stoma closes

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11
Q

Define stomata

A

complex of guard cell and stoma

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12
Q

What of the chloroplast is analogous to the inner membrane?

A

thylakoid

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13
Q

what of the chloroplast is analogous to the matrix?

A

stroma

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14
Q

what of the chloroplast is analogous to the mitochondrial intermembrane space?

A

thylakoid lumen

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15
Q

What type of light drive photosynthesis? (absorbed, transmitted or reflected)

A

absorbed

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16
Q

What type of light is the most useful for photosynthesis?

A

visible light

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17
Q

What types of light do leaves absorb and which one does it reflect?

A

absorb: violet, blue, and red
reflect: green
most important wavelength is blue and red regions

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18
Q

Do shorter wavelengths have lower or higher energy?

A

Higher

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19
Q

Do longer wavelengths have lower or higher energy?

A

lower energy

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20
Q

what are the 3 types of pigment in the thylakoid?

A

chlorophyll a
chlorophyll b
carotenoids

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21
Q

What is the structure chlorophyll a?

A

-complex ring structure- porphyrin ring
has 8 smaller rings
- long hydrocarbon side chain (non polar and anchors chlorophyll in the thylakoi)

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22
Q

What atoms do the ring structure of chlorophyll are composed of and what is the central atom?

A

carbons and nitrogens
central- magnesium

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23
Q

What reactions do chlorophyll a initiate? What lights does it reflect or absorb?

A

reactions- light-dependent reactions
reflect- green
absorb- blue and red

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24
Q

Describe structure of chlorophyll b

A

same as chlorophyl but has a carbonyl group instead of carboxyl

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25
Q

What is another difference between chlorophyll and b

A

b absorbs different wavelengths- appears yellow-green

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26
Q

What lights does carotenoids reflect and absorb?

A

absorbs: violet and blue-green light
reflects- yellow and orange

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27
Q

What is the function of carotenoids?

A

accessory pigment
can transfer energy to chlorophyll a
serve as antioxidants

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28
Q

Absorption spectra of chlorophyll a

A

400-500
650-700

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29
Q

Absorption spectra of chlorophyll b

A

400-500
580-700

30
Q

Absorption spectra of carotenoids

A

400-510

31
Q

Action spectrum of rate of photosynthesis

A

decreases during green light

32
Q

Describe Engelmann’s experiment

A

most photosynthetically active regions will have highest concentrations of bacteria which was mainly in the regions of red and violet light showing they had the most photosynthetic activity. Green light did not have any

33
Q

Where does the light dependent reactions take place?

A

thylakoid membrane

34
Q

beginning molecules of light-dependent reactions

A

Light, CO2, NADP+, ADP and H2O

35
Q

enzymes of light-dependent reactions

A

NADP+ reductase - reduces NADP+ to NADPH
magnese containing enzyme splits water

36
Q

End products of light dependent reactions

A

NADPH and ATP and O2

37
Q

Photosystem II

A

1st absorbs wavelength at 680 nm

38
Q

photosystem I

A

absorb wavelength at 700 nm

39
Q

What is the first step of light dependent reactions

A

light strikes PSII in teh ligth harvesting complex and passes through each pigment to reach chlorophyll a in P680 causing the electron to get excited & reach a higher energy level. Then, the electron is accepted by primary electron acceptor.

40
Q

What happens to PSII when the electron is lost?

A

water is split into 2 e-, 2H+, and 1/2O2. Those electrons replace the ones that left

41
Q

What happens to the electrons that went off to the primary electron acceptor?

A

Excited electrons move from primary electron acceptor of PSII through ETC to PSI

42
Q

What happens to the electrons in PSI?

A

light hits pSI and energy is transferred to reaction enter and joins the p700 pair of chlorophyll which excites them. Lost electron get replaced by electron from PSII. The PSI electrons go to ETX

43
Q

What happens to the electrons after PSI

A

They move through the ETC and to the outside into the stroma and get accepted by NADP+ reducing it to NADPH by enzyme NADP+ reductase

44
Q

Describe the process of chemiosmosis in light dependent reactions?

A

electrons passing (exergonic) powers the active transport of H+ from the stroma to the thylakoid lumen (endergonic). pH of lumen decreases. H+ diffuse through ATP synthase (exergonic) powers the making of ATP (ADP+P0

45
Q

What are the 2 parts photosystems have?

A

reaction center and light harvesting complex

46
Q

define reaction center

A

made of chlorophyll a and primary electron acceptor

47
Q

define light harvesting complex

A

protein and chlorophyll

48
Q

What’s the basic difference between the mitochondrial etc chain and the chloroplast?

A

there are 2 in chloroplast

49
Q

where does the calvin cycle take place?

A

stroma of chloroplast

50
Q

beginning molecules of calvin cycle

A

ATP, NADPH, and CO2

51
Q

End products of calvin cycle

A

G3P

52
Q

What are the 3 steps of the calvin cycle?

A

carbon fixation
reduction
regenertaion

53
Q

describe carbon fixation

A

CO2 molecule combines with RuBP (5 carbon acceptor molecules) –> split into 2 molecules of 3-PGA . reaction is catalyzed by rubisco

54
Q

define reduction

A

NADPH donates electrons (reduced) a 3 carbon intermediate to make G3P (3 carbons sugar)

55
Q

define regeneration

A

some G3P molecules go onto make glucose and while other must be recycled to regenerate RuBP acceptor. ATP is necessary

56
Q

How many turns of the calvin cycle is necessary to make 1 G3P?

A

3 turns

57
Q

How many turns of the calvin cycle is necessary to make glucose?

A

6 turns

58
Q

What are the names of the plants (general class name) that use the normal Calvin cycle?

A

C3 plants

59
Q

What the two problems plants face?

A
  1. plants risk losing CO2 and water bc of the open stoma
    2, rubisco is fickle will bind to CO2 and O2 depending on the abundance of either
60
Q

define photorespiration

A

wasteful process for plants because Rubisco binds with O2 instead of CO2, which prevents glucose production–> carbon fixation won’t occur

61
Q

what are the 2 plants that deal with this problem?

A

C4 plants and CAM plants

62
Q

How do C4 deal with the problem?

A

structured solution- incorporates CO2 into 4 carbon compound in mesophyll cells and those 4 carbon compounds are exported to bundle sheath cells and release CO2 for usage in calvin cycle –> PEP carboxylase is used

63
Q

How do CAM plants deal with this issue?

A

stomata opens at night to load CO2 and closes during day to perform calvin cycles

64
Q

define photons

A

a tiny particle that comprises waves of electromagnetic radiation. It causes an electron to get excited

65
Q

difference between absorption of ligth and transmitted

A

absorption: when light strikes and its energy is absorbed by the material
transmitted- passing of light w/o absorption

66
Q

At which measure does PSII absorb the best?

A

680 nm

67
Q

At which measure does PSI absorb the best?

A

700 nm

68
Q

Light intensity effect on photosynthesis

A

increase until chlorophyll get damaged
light-dependent reactions doesn’t depend on temperature

69
Q

CO2 effect on photosynthesis

A

increase CO2 = increased rate of photosyntheiss, plateus until max fixation is reached

70
Q

Temperature effect on photosynthesis

A

light independent reactions depend on heat because of enzymes
increases until optimal temperature is met; denatures when temperature exceeds that