L5 - photosynthesis Flashcards

1
Q

what is the energy flow of photosynthesis?

A

light captured by chloroplast, water and carbon dioxide is converted into carbohydrates, oxygen becomes a by-product, the mitochondria breaks down carbohydrates, and chemical energy is released and stored and as ATP

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2
Q

what is the first intermediate of photosynthesis?

A

a triose sugar (3-carbon)

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3
Q

how many molecules of water is needed to convert three molecules of carbon dioxide into a triose sugar?

A

6

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4
Q

what is the end produce of photosynthesis?

A

glucose (6-carbon sugar)

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5
Q

what is anoxygenic photosynthesis?

A

photosynthesis using hydrogen sulfide instead of stripping electrons off water

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6
Q

in anoxygenic photosynthesis, what is produced instead of oxygen within the cell?

A

sulfur

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7
Q

how was energy produced before photosynthesis?

A

all energy on the planet was essentially conserved - the atmosphere was mostly nitrogen

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8
Q

what happened after photosynthesis began?

A

there was an endless supply of solar energy, oxygen was being produced as a by-product which allowed for the creation of biomass

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9
Q

what organism first began using photosynthesis?

A

cyanobacteria - capable of splitting water into hydrogen and oxygen

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10
Q

what are the closest relatives of cyanobacteria?

A

Melainabacteria and Sericytochromatia (cannot photosynthesize)

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11
Q

what is the evolution of photosynthesis?

A

it had evolved once in Chloroflexus, and was transferred between distant lineage - no common ancestral pathway

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12
Q

how was the ability to photosynthesize in bacteria passed on?

A

horizontal gene transfer

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13
Q

what is the summary of photosynthesis evolution?

A

evolution of oxygenic photosynthesis likely happened several times however, origin is probably of one source. HGT spread capability to distant bacterial lineages and cyanobacteria was the precursor to chloroplasts and photosynthesis in plants

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14
Q

plants are ___ autotrophs

A

photo autotrophs

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15
Q

what are chemotrophs?

A

obtain energy by oxidation of electron donors in their environments, using Fe2+ as an electron donor and radiant energy to assimilate CO2 into biomass

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16
Q

short rays = …

A

more energy

17
Q

what is the photoelectric effect?

A

light energy dislodges electrons from metal atoms - in other words, it is the emission of electrons from a material when light hits

18
Q

what is the color we see in terms of wavelength when we look at plants?

A

we see the color that is reflected off the plant, i.e., what is not absorbed by the pigment

19
Q

what is the significance of the color absorbed?

A

its the light energy being captured by plant systems

20
Q

what is the action spectrum?

A

the effectiveness of different wavelengths for a specific process

21
Q

what happens when chlorophyll absorbs light?

A

electrons boosted to higher energy, putting them in the excited state

22
Q

how do electrons release energy?

A
  1. heat and fluorescence
  2. resonance energy transfer
  3. electron transport chain
23
Q

where does chlorophyll a occur?

A

in all photosynthetic eukaryotes and cyanobacteria

24
Q

significance of chlorophyll a

A

essential for photosynthesis, the primary pigment

25
Q

what is the accessory pigment that plants and algae also have?

A

chlorophyll b

26
Q

what are carotenoids?

A

accessory pigments, like chlorophyll b

found in all chloroplasts and cyanobacteria

appears red, orange, or yellow

lipid soluble pigments

27
Q

what are the two types of carotenoids?

A

carotene and xanthophyll

28
Q

who produces carotenoids?

A

only plants

29
Q

what is beta-carotene?

A

the principal source of vitamin A in animals - a kind of carotenoid

30
Q

how are carotenoids protective?

A

they protect chlorophyll from photodamage

31
Q

what are phycobiliproteins?

A

an accessory pigment found in cyanobacteria and red algae.
They can absorb red, orange, yellow, and green light.
Transfer energy to chlorphyll.
Are classified as water-soluble proteins.
bound to phycobilin, a pigment/chromophore

32
Q

what organisms are phycobiliproteins mnainly necessary for?

A

organisms living in deeper marine environments

33
Q

why are several pigments used?

A

pigments allow complementary roles and modulate over seasons

34
Q

what is the difference between carotenoids and phycobilins?

A

carotenoids are in the blue-green range and phycobillins are in the red-to-green range

35
Q

what are the two stages photosynthesis occurs in?

A

light-dependent and carbon-fixation

water is oxidized, donates electrons
carbon is reduced, gains electron