L5 - photosynthesis

Question 1

what is the energy flow of photosynthesis?

Answer 1

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

Question 2

what is the first intermediate of photosynthesis?

Answer 2

a triose sugar (3-carbon)

Question 3

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

Answer 3

6

Question 4

what is the end produce of photosynthesis?

Answer 4

glucose (6-carbon sugar)

Question 5

what is anoxygenic photosynthesis?

Answer 5

photosynthesis using hydrogen sulfide instead of stripping electrons off water

Question 6

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

Answer 6

sulfur

Question 7

how was energy produced before photosynthesis?

Answer 7

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

Question 8

what happened after photosynthesis began?

Answer 8

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

Question 9

what organism first began using photosynthesis?

Answer 9

cyanobacteria - capable of splitting water into hydrogen and oxygen

Question 10

what are the closest relatives of cyanobacteria?

Answer 10

Melainabacteria and Sericytochromatia (cannot photosynthesize)

Question 11

what is the evolution of photosynthesis?

Answer 11

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

Question 12

how was the ability to photosynthesize in bacteria passed on?

Answer 12

horizontal gene transfer

Question 13

what is the summary of photosynthesis evolution?

Answer 13

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

Question 14

plants are ___ autotrophs

Answer 14

photo autotrophs

Question 15

what are chemotrophs?

Answer 15

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

Question 16

short rays = …

Answer 16

more energy

Question 17

what is the photoelectric effect?

Answer 17

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

Question 18

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

Answer 18

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

Question 19

what is the significance of the color absorbed?

Answer 19

its the light energy being captured by plant systems

Question 20

what is the action spectrum?

Answer 20

the effectiveness of different wavelengths for a specific process

Question 21

what happens when chlorophyll absorbs light?

Answer 21

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

Question 22

how do electrons release energy?

Answer 22

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

Question 23

where does chlorophyll a occur?

Answer 23

in all photosynthetic eukaryotes and cyanobacteria

Question 24

significance of chlorophyll a

Answer 24

essential for photosynthesis, the primary pigment

Question 25

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

Answer 25

chlorophyll b

Question 26

what are carotenoids?

Answer 26

accessory pigments, like chlorophyll b

found in all chloroplasts and cyanobacteria

appears red, orange, or yellow

lipid soluble pigments

Question 27

what are the two types of carotenoids?

Answer 27

carotene and xanthophyll

Question 28

who produces carotenoids?

Answer 28

only plants

Question 29

what is beta-carotene?

Answer 29

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

Question 30

how are carotenoids protective?

Answer 30

they protect chlorophyll from photodamage

Question 31

what are phycobiliproteins?

Answer 31

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

Question 32

what organisms are phycobiliproteins mnainly necessary for?

Answer 32

organisms living in deeper marine environments

Question 33

why are several pigments used?

Answer 33

pigments allow complementary roles and modulate over seasons

Question 34

what is the difference between carotenoids and phycobilins?

Answer 34

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

Question 35

what are the two stages photosynthesis occurs in?

Answer 35

light-dependent and carbon-fixation

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