Gas Exchange in Dicotyledonous Plants Flashcards
Define dicotyledonous
A plant with 2 seed leaves/cotyledons
What gases are useful and which are waste products for a plant
CO2 is useful for photosynthesis
Small amounts of O2 are useful for respiration
EXCESS O2 is a waste product, too much O2 kills them
What do plants need a well adapted exchange system for
Getting CO2 in and O2 out
What are the parts that make up the structure of a leaf
Waxy cuticle
Upper epidermis
Palisade mesophyll
Spongy mesophyll
Vascular bundle
Xylem and phloem
Lower epidermis
Guard cells
Stomata
What 3 parts of a plant are adapted for gas exchange
Palisade mesophyll
Spongy mesophyll
Guard cells & stomata
How is the palisade mesophyll adapted for gas exchange
It is near the top of the surface of the leaf and is packed full of chloroplasts to do as much photosynthesis as possible
Has lots of cells packed together giving it a large surface area
How is the spongy mesophyll adapted for gas exchange
It has air spaces around it for the gases to reach the palisade mesophyll
Has a large surface area for lots of gas exchange to happen at once
How are the guard cells and stomata adapted for gas exchange
Guard cells control the opening and closing of the stomata allowing gases in and out of the plant at appropriate times - open during the day, closed at night
What are stomata the equivalent to in insects? What problem can this mean
To spiracles in insects. This can mean water loss is a problem
What do the stomata do to limit water loss
Open and close depending on the time of day and the weather conditions
How do the stomata open and close
When water is in good supply, it enters the vacuole of the guard cells, making them turgid and causing the stomata to open
When the plant is dehydrated, guard cells lose water and become flaccid which causes the stomata to close
What is a xerophyte
A plant which is adapted to live in dry conditions
How are xerophytes adapted to live in dry conditions
Leaves are dry and closed and the inner side of them has the stomata sunk in pits. This limits water loss in plants
The inside of the leaf has hairs. This helps close and trap water
Leaves have a waxy waterproof cuticle. This reduces evaporation
