Plant Tissue Structure Flashcards
At the top and bottom of the leaf is the-
Upper epidermis and lower epidermis
The epidermis protects the surface of the leaf
Key adaptations of the upper epidermis (2)
It is transparent so allows light to pass through to the photosynthetic cells below
UE is covered with a layer of oily material, called waxy cuticle, this reduces the evaporation of water from the surface of the leaf. This prevents leaf from drying out
What is the stomata and what does it do, (found in lower epidermis)
The stomata allows carbon dioxide to enter the leaf and the oxygen to leave
What does stomata help
Helps to control the amount of water vapour that can pass out of the leaf
Function of palisade mesophyll
Palisade cells are packed full of Chloroplasts. Chloroplasts contain chlorophyll which absorbs the light needed for photosynthesis.’
Function of spongey mesophyll
It is full of air spaces which allows carbon dioxide to diffuse from the stomata through the spongey mesophyll and to the palisade cells
Oxygen also diffuses from the palisade cells, through spongey mesophyll and to the stomata
Xylem tissue function
Transports water and dissolved minerals from the roots to the stem and the leaves
Some of this water is then used in photosynthesis
Dissolved mineral ions such as magnesium can be used to make chlorophyll
Phloem tissue function
Phloem tissue transports dissolved sugars produced by photosynthesis from the leaves to the rest of the plant
These sugars can be used immediately e.g glucose in respiration or stored e.g starch
Definition of translocation
The movement of sugars and other molecules through phloem tissue
Where is meristem tissue found
Tips of roots or shoots
What is the process of transpiration
Water constantly evaporating from the surface of the leaf
Factors that affect the rate of the transpiration stream
- rate is greater at higher temperatures (evaporation is faster when temp is higher)
- rate increases in windy conditions (wind removes water vapour so water can evaporate)
- rate increases when light intensity increases, more light = more photosynthesis
How to stomata work
Surround by 2 gaurd cells
When the light intensity is high (during day) guard cells swell and change shape, causing stomata to open, so co2 can diffuse into leaf and be used in photosynthesis.
What happens to stomata under hot condition
Plant closes it’s stomata to reduce water loss by transpiration, but plant cannot photosynthesise
