KA5- Transport Systems In Plants Flashcards
What is needed for more efficient diffusion/exchange of materials between an organism and its external environment?
Organisms must have a large surface area to volume ratio
What are the features of a leaf
Large surface area to maximise light absorption
Thin short distance for carbon dioxide to diffuse into leaf cells
Thin waxy cuticles and thin transparent epidermis protects the leaves without blocking out light for palisade mesophyll cells
What are the main organs of a leaf
Roots
Stems
Leaves
What do plants require water for
Photosynthesis
Transporting minerals
What are the cells in a leaf
Upper epidermis
Palisade mesophyll
Spongy mesophyll
Veins
Lower epidermis
Stomata
Guard cells
Upper epidermis
Protective layer
Transparent
Palisade mesophyll
Carry out photosynthesis
Spongy mesophyll
Large surface area between them allowing gas exchange between stomata and photosynthesis cells
Veins
Contain xylem and phloem
lower epidermis
Contains stomata
Protective layer
Stomata
Pores on lower epidermis surrounded by guard cells to regulate the rate of transpiration
Guard cells
Pairs of cells that change shape to open and close the stomata
Root hair cells
Specialised cells
Water and minerals enter by osmosis/ active transport, surface area increased
Water then moves up through plant in xylem vessels
Xylem
Have rings of lignin which provides strength to withstand the water pressure changes through the plant
Direction of water in plants
Only moves from the roots up the plants out through the lease
What is transpiration
Process of water moving through a plant and evaporating through the stomata
Measured using a potometer
Helps cool down plants
What does transpiration consist of
The movement of water into root hair cells by osmosis
The movement of water up the plant through the xylem
Evaporation of water through the stomata
What affects the rate of transpiration
Temperature- increases the rate
Wind intensity- increases the rate
Large surface area- increases the rate
Small surface area- decreases the rate
Humidity- decreases the rate
Phloem
Transport food up and down
Sugar produced by photosynthesis transported on phloem vessels to provide energy for the growth and repair
Sieve plates to control what moves from phloem cell to cell
Companion cells to carry out the cellular processes
Hydrated guard cell
They become turgid which causes the stomata to open, allowing the water to evaporate
Dehydrated guard cell
It loses water and becomes flaccid causing teh stomata to close
Happens when the plant isnt photosynthesising
