Plant Structures And Their Functions Flashcards
What is photosynthesis
It is a series of chemical reactions catalysed (sped up) by enzymes
Where does photosynthesis occur
And what is it
Chloroplasts
It contains a green substance called chlorophyll that traps energy transferred by light
Where does sucrose come from
Starch gets broken down into simpler substances into the cytoplasm creating sucrose
What does sucrose make around the plant
Starch (in a storage organ such as a potato )
Other molecules for the plant ( such as cellulose, lipids or proteins)
Glucose for respiration ( to release energy)
What do palisade cells do and where are they located
They are packed with chloroplasts allowing a leaf to absorb a great amount of life
They are located near the top of the leaf under the upper epidermis
What is the order of a leaf
First wax coating
Upper epidermis containing tightly packed cells
Second
Layer of palisade cells which are packed with chloroplasts shielded by a cell wall
Third
Cytoplasm
Air spaces provide a large surface area for cells to exchange gasses with the air
Fourth
Lower epidermis containing stomata
And vacuole and guard cell
What can be limiting factors for photosynthesis
Carbon dioxide concentration, temperature and light intensity
What is the water absorbed into plant roots used for
Carrying dissolved mineral ions
Keeping cells ridged (otherwise the plants wilt their leafs and stems droop)
Cooling the leafs ( when it evaporates from them)
Photosynthesis
What are the features of root hair cells
Large surface area so water and mineral ions can be absorbed
The hairs also have thin cell walls so that the flow of water into the cells is not slowed down
What is osmosis
Is when solvent molecules (e.g water) diffuse though a semi permeable membrane they diffuse from where there is more of them to where there are fewer
What does photosynthesis need from the air and how does it get into the leaf
It needs carbon dioxide it comes through the stomata which allows it to diffuse Into the leaf
What do guard cells do
They open the stomata to let through the substances for photosynthesis
E.g carbon dioxide
How do the guard cells open
In the light water flows through making the guard cells ridged which open the stoma
How do the guard cells close
At night the water flows out the guard cells they loose there rigidness which courses them to close
Why are leafs thin
So that carbon dioxide does not have far to diffuse into the leafs before reaching the cells that need it
What els does the stomata do
The stomata allows oxygen produced by photosynthesis to escape into the air as well a water vapour
How does diffusion occur in plant roots
The cell walls have an open structure allowing the water particles to diffuse toward the middle of the root
What are mineral salts and why are they needed
They are naturally occurring ionic compounds
Plants need ions from these compounds to produce new substances for example nitrate ions are needed to make proteins
What do proteins do from the cell membrane
They pump ions into the cell this is and example of active transport
What is transpiration
It is the flow of water up the stem and out the leaves
What are xylem vessels
They are tiny continuous pipes leading from the plants roots up into its leaves
What happens to the water after it is delivered by the xylem
Water is pulled up the xylem vessels into stem as water evaporates from the xylem vessels into the leaves the water vapour diffuse out the leaf
Why are xylem cells ridged
Why
Because they have thick side walls and rings of hard lignin so the water pressure inside the vessels does not burst
What do companion cells do
They actively pump sucrose into or out of the sieve cells that form sieve tubes
