photosynthesis Flashcards
metabolism
chemical processes in organisms controlled by enzymes
anabolism
building up chemical reactions
catabolism
breaking down chemical reactions
iodine solution
chemical used to test for starch – a positive test results in the
colour changing from brown to blue-black
autotrophic
green plants that produce their own food through
photosynthesis
heterotrophic
organisms that cannot photosynthesize and obtain food from
other organisms
define photosynthesis
the building up of organic compounds (glucose) from CO2 and H2O using radiant energy from the sun trapped by chlorophyll in chloroplasts, oxygen is released as a bi product
chloroplast
organelle in plants, site for photosynthesis
chlorophyll
green pigment needed for photosynthesis
thylakoids
part of the chloroplast that contains chlorophyll
grana
stacks of thylakoids, light dependent phase of photosynthesis
takes place here (lig)
stroma
liquid part of the chloroplast, light independent phase of
photosynthesis takes place here
what are the 6 adaptations of chloroplasts for photosynthesis
1- double membrane = permeable to H2O and CO2 + radiant energy
2- starch granules = temp store starch produced
3- grana made of lamellae (thin flat discs) = give large SA for absorption of sunlight
4- grana contains chlorophyll= trap sunlight
5- stroma contains enzymes= reactions for Dark phase (Das)
6- stroma contains ribosomes = synthesise enzymes for photosynthesis
photolysis
splitting of water molecules into oxygen atoms and hydrogen
atoms. photo = light, lysis = split
phosphorylation
formation of energy transporting molecules called ATP
ATP
adenosine triphosphate, energy carriers in cells
Calvin cycle
cyclical process during the light-independent phase of
photosynthesis, aka dark phase, where glucose (C6H12O6) is formed from energy-rich H-atoms combined with CO2 using enzymes like ATP and NADPH
glucose
carbohydrate formed during photosynthesis
starch
stored form of glucose in plants
light phase 5 characteristics
1- Occurs in the grana
2-Light is required
3- chemosynthesis: radiant energy from the sun converted into chemical energy . Radiant energy is absorbed and used for the
reactions of photolysis & phosphorylation
4- Photolysis occurs: splitting of H2O.hydrogen is released and
oxygen is returned to the atmosphere
5- Phosphorylation occurs: ATP is produced
5 characteristics of dark phase/ calvin cycle
1- Occurs in the stroma
2- light not req
3- Carbon dioxide is absorbed from
the atmosphere
4- Hydrogen and carbon dioxide
combine by using atp to form
glucose. hydrogen from light phase
5- Excess glucose is stored as starch
importance of photosynthesis
1- prov food = trophic levels, transfer of energy. It uses radiant energy to produce chemical potential energy in the form of
glucose which serves as food for other organisms.
2- It balances the levels of carbon dioxide and oxygen in the atmosphere
3- The process uses carbon dioxide and releases oxygen.
describe 9 structures of leaf layers, how it helps photosynthesis
1- cuticle= thin layer, 1) thin + transparent, allows light to easily pass through, 2) waxy, reduce water loss
2- epidermis= layer after cuticle, 1)single layer, light easily pass through, 2) transparent
3- palisade mesophyll= 1)contains chloroplasts, max trap of light energy, 2) elongated for deep penetration of radiant energy, 3) thin walls for entry of CO2 and H2O
4- spongy mesophyll= 1) thin walls for entry of CO2 and H2O, 2) chloroplasts trap light energy, 3) irregular shape creates intercellular space betw cells
5- intercellular space = allows for gaseous exchange of CO2 and O2
6- xylem = transp of water and minerals through the plant to cells that req it to make glucose and perform other imp functions
7- phloem= transp products of photosynthesis to keep plant alive
8- stoma= abundant on ventral (bottom) surface for exchange of CO2 and O2, away from sun to reduce water loss via transpiration
9- guard cell = controls opening and closing of stoma
