4B: resources from plants Flashcards
role of the cell wall
supports the plant cell
what is a cell wall
rigid structure that’s surrounds plane cell - made of cellulose
what is the middle lamella
the outermost layer of the cell
role of the middle lamella
acts like an adhesive, sticking adjacent plant cells together and gives the cell stability
what is the plasmodesmata
channels in the cell walls that link adjacent cells together
role of the plasmodesmata
allows transport of substances and communication between cells
what is pits in a plant cell
regions of the cell wall that are very thin - paired up with adjacent cell so that the pits line up with eachother
role of the pits in plant cells
allows transport of substances between cells
what are chloroplasts
a small flattened structure with a double membrane which contains membranes inside it aswell. The membranes are stacked to form grana. Filled with a thick fluid called stroma
role of chloroplast
the site where photosynthesis takes place - some of the process take place in the grana & some in the stroma
what are amyloplasts
a small organelle enclosed by a membrane - contains starch granules
role of amyloplasts
storage of starch grains - convert starch back to glucose for release
what is the vacuole and tonoplast
the vacuole is a compartment surrounded by the membrane called the tonoplast
role of the vacuole and the tonoplast
vacuole: contains cell sap - keeps cell turgid, involved in breakdown and isolation of unwanted chemicals in the cell
tonoplast: controls what enters and leaves the vacuole
what is cellulose
a polysaccharide made of beta glucose
what is the structure of cellulose
long unbranched chain of beta glucose with 1-4 glycosidic bonds
cellulose chains are linked together with hydrogen bonds to form strong threads called microfibrils which help provide structural support
function of cellulose in a plant cell wall
- prove structural support for the cell
- allows substances to pass in and out of cell freely
- gives the cell shape
what features makes plant fibres strong
- the arrangement of cellulose microfibrils in the cell walls
- the secondary thickening of a cell wall
how does the arrangement of cellulose microfibrils help make strong plant fibres
net like arrangement
how does the secondary thickening of the cell wall help make strong plant fibres
between cell walls & cells membrane, a secondary cell wall forms
- has more lignin
how can the arrangement of cellulose microfibrils and secondary cell wall thickening be explored by humans
due to being strong, they can be used for ropes and fabrics like hemp
how does the arrangement of cellulose microfibrils and secondary wall thickening contribute to the physical properties of xylem & sclerenchyma
creates strong plant fibres due to lignin development - which helps with the strength of the vessels walls
what is starch
the main energy source in plants (storage polysaccharide)
what is starch made up of
2 alpha glucose polysaccharides
amylose & amylopectin
what is the structure of amylose
long, unbranched chain of alpha glucose
- coiled
- compact
what is the structure of amylopectin
long, branched chain of alpha glucose
- more compact than amylose
what is the role of hydrogen bonds between the beta glucose sheets in the formation of glucose microfibils
link cellulose chains together to form strong threads which can be used practically for humans and to help provide structural support for the plant cell
what is the function of the xylem
vessel used to transport water and mineral ions up from the roots to the leaves of a plant (transpiration)
what is the function of the phloem
vessel used to bidirectly transfer organic solutes around the plant (translocation)
what is the function of the sclerenchyma fibres
fibres that provide support to vessels
what is the structure of the xylem
long tube formed from dead cells
- hollow lumen
- no end walls
- walls thickened by lignin
what is the structure of the phloem
arranged in tubes
sieve cells
- living cells
- have holes in them to allow transport of solutes
- thin layer of cytoplasm
- no nucleus therefore have companion cells
what is the structure of a sclerenchyma fibre
made of dead cells that run vertically up the stem of a plant
- hollow lumen
- have end walls
- have more cellulose
- strengthened w lignin
