Organisation in plants Flashcards
Function of waxy cuticle
Makes leaf waterproof
Function of upper epidermis
Protects against water loss
Characteristics of upper epidermis
Single layer of cells
Transparent to allow light to pass through
Adaptions of palisade mesophyll
Tightly packed cells with many chloroplasts to absorb as much light as possible for photosynthesis
Adaptions of spongy mesophyll
Air spaces increase SA to allow gases to diffuse quickly
Function of stomata
Tiny openings on lower surface of leaf to allow gases to move in and out of
Functions of guard cells
Control opening and closing of stomata
What do stomata control
Gas exchange and water loss
How do stomata control gas exchange and water loss
Allowing diffusing of carbon dioxide into plant for photosynthesis
Allowing diffusion of oxygen out of plant
How to guard cells become turgid
When plants have lots of water
What is transpiration
Movement of water from roots to the leaves through the xylem
What is the purpose of transpiration
Provide water to keep cells turgid
Provide water for photosynthesis
Transport mineral ions to leaves
Function of xylem
Transport water and mineral ions from roots to rest of plant
3 adaptations of xylem
Made of dead cells
No end wall between cells
Walls strengthened by chemical called lignin to withstand water pressure
What is purpose of translocation
Transport dissolved sugars from leaves to other parts of plant for respiration, growth, storage
Function of phloem
Transport dissolved sugars from leaves to rest of plant
4 factors that affect rate of transpiration
Temp, light intensity, humidity, wind speed
What effect does temp have on rate of transpiration and why
Higher temps increase rate because water evaporates faster
What effect does humidity have on rate of transpiration and why
Higher levels of humidity decrease rate of transpiration because there is a steeper concentration gradient of water molecules between the air and leaf
How does the wind speed effect the rate of transpiration and why
More wind increases rate of transpiration because wind removes water vapour quickly maintaining the steep concentration gradient
How does light intensity effect the rate of transpiration and why
Higher light intensity increases rate of transpiration because the stomata will open wider to let more carbon dioxide in for photosynthesis
Why do root hair cells have a large SA
To increase absorption of water and mineral ions into root
Why do roots hair cells have lots of mitochondria
To transfer a lot of energy for intake of mineral ions by active transport
