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BIO 202 > Chapter 10 > Flashcards

Chapter 10 Flashcards

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Biology 101 flashcards
1
Q

Photosynthesis

A

-process that converts solar energy into chemical energy
-nourishes entire living world
-in plants, algae, protists and some prokaryotes

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2
Q

Autotrophs

A

-sustain themselves without eating anything derived from other organisms
-producers
-produce organic molecules from CO2 and other inorganic molecules

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3
Q

Photoautotrophs

A

-almost all plants
-use energy of sunlight to make organic molecules

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4
Q

Chemoautotrophs

A

-autotrophic organisms that oxidize an inorganic or organic compound as source of energy

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5
Q

Heterotrophs

A

-obtain organic material from other orgabisms
-consumers
-feed on other organisms
-decomposers
-depend on photoautotrophs for food and O2

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6
Q

Chloroplasts

A

-sites of photosynthesis
-found mainly in cells of mesophyll
-structurally similar to and likely evolved from photosynthetic bacteria
-organization allows for chemical reactions of photosynthesis

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7
Q

Endosymbiont theory

A

-suggest that original chloroplast was photosynthetic prokaryote that lived inside eukaryotic cell
-has circular dna and ribosomes

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8
Q

Leaves

A

-major locations of photosynthesis
-green color from chlorophyll

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9
Q

Chlorophyll

A

green pigment within chloroplasts
-in thylakoids

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10
Q

Mesophyll

A

-interior tissue of the leaf
-contains 30-40 chloroplasts

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11
Q

Stomata

A

-pores for gas exhacngae
-co2 enters and O2 exits

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12
Q

Thylakoids

A

-connected sacs in chloroplast
-can be stacked in columns
-contain chlorophyll

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13
Q

Grana

A

-stacked columns of thylakoids

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14
Q

Stroma

A

-dense interior fluid in chloroplasts

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15
Q

Photosynthesis equation

A

6 CO2 +12 H2O +light energy –> C6H12O6 + 6 O2 + 6H2O

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16
Q

What happens in photosynthesis

A

-chloroplasts split H2O into hydrogen and oxygen, incorporating electrons of hydrogen into sugar molecules and releasing oxygen as by product
-reverses direction of electron flow compared to respiration
-redox process (H2O is oxidized, CO2 is reduced)
-endergonic process, energy boost from light

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17
Q

Two stages of photosynthesis

A

-light reactions and Calvin cycle

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18
Q

Light reactions

A

-in thylakoids
-split H2O
-release O2
-reduce NADP+ to NADPH
-generate ATP from ADP by photophosphorylation
-convert solar energy to chemical energy of ATP and NADPH

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19
Q

Calvin cycle

A

-in stroma
-forms sugar from CO2 using ATP and NADPH
-begins with carbon fixation incorporating CO2 into organic molecules

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20
Q

Light

A

-form of electromagnetic energy or electromagnetic radiation
-travels in rhythmic waves

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21
Q

Wavelength

A

-distance between crests of waves
-determines type of electromagnetic energy
-short wavelengths=high frequencies
-long wavelengths=low frequencies, frequency inversely proportional to wavelength

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22
Q

Electromagnetic spectrum

A

-entire range of electromagnetic energy or radiation

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23
Q

Visible light

A

-consists of wavelengths like those that drive photosynthesis that produce colors we can see

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24
Q

Energy of photons

A

-inversely related to wavelength

25
Q

Pigments

A

-substances that absorb visible light
-different pigments absorb different wavelengths
-wavelengths not absorbed are reflected or transmitted
(leaves green because chlorophyll rejects and transmits green light)

26
Q

Absorption spectrum

A

-graph plotting a pigments light absorption versus wavelength
-of chlorophyll a- violet blue and red light work best for photosynthesis

27
Q

Action spectrum

A

-profiles the relative effectiveness of different wavelengths of radiation in driving a process

28
Q

Engelmanns experiment

A

-1833
-exposed different segments of filamentous alga to different wavelengths
-areas receiving wavelengths favorable to photosynthesis produced excess O2
-used growth of aerobic bacteria clustered along the alga as measure of O2 production

29
Q

Chlorophyll a

A

-main photosynthetic pigment

30
Q

Chlorophyll b

A

-accessory pigment
-broaden spectrum used for photosynthesis

31
Q

Carotenoids

A

-accessory pigments
-absorb excessive light that would damage chlorophyll

32
Q

What happens when pigment absorbs light

A

-goes from ground state to excited state which is unstable
-excited electrons fall back down to ground state and photons are given off (afterglow called fluorescence)

33
Q

Isolated solution illuminated

A

-of chlorophyll will fluorescence
-giving off light and heat

34
Q

Photosystem

A

-consist of reaction center complex (type of protein complex surrounded by light harvesting complexes)

35
Q

Light harvesting complexes

A

-pigment molecules bound to proteins
-transfer energy of photons to reaction center

36
Q

Primary electron acceptor

A

-in the reaction center accepts excited electrons and is reduced

37
Q

First step of light reactions

A

-solar powered transfer of electron from chlorophyll a molecule to primary electron acceptor

38
Q

2 types of photosystems

A

-in thylakoid membrane
-photosystem II and photosystem I

39
Q

Photosystem II

A

-functions first
-best at absorbing a wavelength of 680 nm
-reaction center chlorophyll a of PS II- P680

40
Q

Photosystem I

A

-best at absorbing wavelength of 700 nm
-reaction center chlorophyll a of PS I- P700

41
Q

2 possible routes for electron flow in light reactions

A

-cyclic and linear
-electrons flow through photosystems and other molecular components in thylakoid membrane

42
Q

Linear electron flow

A

-primary pathway of electron flow in light reactions
-involves photosynthesis and produces ATP and NADPH using light energy

43
Q

Linear electron flow steps

A
  1. photon hits pigment and energy is passed among pigment molecules until it excited P680
  2. excited electron from P680 is transferred to primary electron acceptor (now P680+, strongest biooxidizing agent)
  3. splitting of H2O molecules
    -split by enzyme and electrons are transferred from hydrogen atoms to P680+, reduces it to P680, H+ are released in thylakoid space, oxygen atom combines with oxygen atom generated from splitting forming O2 that is released as byproduct
  4. each electron falls down electron transport chain from primary electron acceptor of PSII to PSI
    5.released energy by fall drives creation of proton gradient across thylakoid membrane
  5. in PSI transferred light energy excites P700 loses an electron to acceptor, P700+ accepts electron from PSII
  6. each electron falls down electron transport chain to ferredoxin
  7. nada reductase transfer two electrons from Fd to NADP+ to reduce to NADPH
44
Q

Plastoquinone (Pq)

A

-cytochrome complex that is electron carrier between PSII and PSI

45
Q

Plastocyanin (Pc)

A

-protein part of electron transporter

46
Q

Cyclic electron flow

A

-only uses photosystem I and produces ATP but not NADPH
-no oxygen released
-generates surplus ATP

47
Q

Chemiosmosis

A

-used by chloroplasts and mitochondria to generate ATP but with different sources of energy and spatial organizations
-mitochondria-chemical energy from food to ATP, protons pumped to intermembrane space and drive atp synthesis as diffuse back into mitochondrial matrix
-chloroplasts- light energy into chemical energy of ATP, protons pumped into thylakoid space and drive atp synthesis as diffuse back into stroma

48
Q

Where are atp and nadph produced

A

-side facing stroma
-where Calvin cycle takes place

49
Q

What do light reactions generate

A

-atp and increase potential of energy of electrons by moving them from H2O to NADPH

50
Q

pH gradient

A

-between stroma and thylakoid space
-substantial when plants are exposed to light
-when illuminated pH in thylakoid drops to 5, stroma increases to 8, 1000X difference
-light turned off=gradient disappears

51
Q

Calvin cycle

A

-regenerates its starting material after molecules enter and leave cycle
-builds sugar from smaller molecules y using atp and reducing power of electrons carried by nadph
-carbon enters as CO2 and leaves as G3P
-for next synthesis of 1G3P cycle must take place 3X fixing 3 molecules of CO2

52
Q

3 phases of Calvin cycle

A

-carbon fixation (catalyzed by rubisco)
-reduction
-regeneration of CO2 acceptor (RuBP)

53
Q

Dehydration

A

-problem for plants
-requres trade offs with other metabolic processes
-hot dry days- plants close stomata to conserve H2O but limits photosynthesis, reduces access to CO2 and causes O2 build up, favor wasteful process called photorespiration

54
Q

Photorespiration

A

-rubisco adds O2 instead of CO2 in Calvin cycle producing two carbon compound
-consumes O2 and organic fuel and releases CO2 without producing ATP or sugar
-limits damaging products of light reactions that build up in absence of Calvin cycle
-drains 50% of carbon fixed by carbon cycle

55
Q

C3 plants

A

-inital fixation of CO2 by rubisco forms 3 carbon compound

56
Q

C4 plants

A

-minimize cost of photorespiration by incorporating CO2 into 4 carbon compounds in mesophyll cells
-requires PEP carboxylase which can fix CO2 even when CO2 concentrations are low
-4 carbon compounds exported to bundle sheath cells where they release CO2 that is used in Calvin cycle

57
Q

CAM plants

A

-use crassulacean acid metabolism (Cam) to fix carbon
-open stomata at night incorporating CO2 into organic acids
-close stomata during day and CO2 is released from organic acids and used in Calvin cycle

58
Q

Importance of photosynthesis

A

-energy entering chloroplasts as sunlight gets stored as chemical energy in organic compounds
-sugar made in chloroplasts supplies chemical energy and carbon skeletons to synthesize organic molecules of cells
-plants store excess sugar as starch
-produces O2 in our atmosphere

BIO 202 (10 decks)

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