Lesson 4: Plant tissue Flashcards
What is the function of the palisade mesophyll?
How is it adapted
- The site of photosynthesis
- Many chloroplasts to absorb light energy by photosynthesis.
What is the function of the upper epidermal tisssue?
- Secretes wax to ensure water doesn’t evaporate from surface.
- Protects plant from infection.
- Transparent –> allows light to pass through to palisade mesophyll.
How is epidermis tissue adapted to allow a good amount of light to reach palisade cells?
- The tissue is transparent.
What is the adaptation of spongy mesophyll tissue?
- Cells have irregular shape to allow gases to diffuse in and out of leaf easily.
What is meristem tissue?
- Tissue that contains cells that can differentiate itnto any type of cell.
- Found at tips of shoots and roots.
Why is meristem tissue important?
- Meristem tissue allows the plant to grow.
What does the waxy cuticle layer prevent?
- Reduces water evaporating
- Prevents plant from wilting.
What is the function of the xylem?
How is it specialised to carry out this function?
Function: Xylem are dead cells that transport water and mineral ions up plant from roots to leaves.
Specialisation
- Made of hollow tubes (no end walls)
- Strengthened by lignin to give strength to plant.
- No internal structures –> water flows more easily.
- Lignin = tough + waterproof
What important ion is used to make chlorophyll?
- Magnesium.
True or False
A leaf is a tissue
False. it is an organ and contains many different tissues.
What is the function of the phloem?
How is it specialised to carry out this function?
Function: Phloem are living cells that transport dissolved sugar (from photosynthesis) up and down the plant for storage or immediate use.
Specialisation:
- Cells are elongated
- Cell sap moves between cells via pores in seive plates (on end walls.)
After sugar is transferred what can the plant cells do with it (2 options)?
- Can be used straight away ie. glucose in respiration
- Can be stored ie. starch.
What 3 main components form the plant organ system?
- Roots
- Stem
- Leaves
Where are xylem found?
- Xylem are found in the stems of plants.
What do sieve plates do in the phloem tissue?
- Sieve plates allow cell sap to move from one phloem cell to another.
What type of cells make up the phloem?
- Elongated cells make up the phloem.
What is the role of the organ system in plants?
- To transport substances around the plant.
What is transpiration?
- Transpiration is the loss of water from surface of leaf by evaporation.
Give the steps of the transpiration stream .
1.) Water evaporates through the stomata via diffusion.
2.) Less water in leaves, more in roots
3.) Water travels from roots to leaves in the xylem
4..) Root hair cells will absorb water by osmosis, xylem tranport it.
Why is transpiration important?
- Water for photosynthesis
- Absorbs mineral ions important for plant.
Why does rate of transpiration increase at high temp?
- Increased evaporation by diffusion because water particles have more energy.
- So particles move further away
- Increased concentration gradient.
- So more water lost by the leaves.
Why does rate of transpiration increase in low humidity?
- Less water vapour
- High concentration gradient in water vapour.
- Water evaporates from stomata by diffusion.
Why does high wind speed increase the rate of transpiration?
- Wind removes water vapour around leaf.
- Mantains concentration gradient
- Allows more water to evporate by diffusion.
Why does a high light intesnity increase the rate of transpiration?
- More photosynthesis
- More water being drawn up
- Stomata open
- Allows water vapour to evaporate