1. Plant Cell Organisation & Specialisation
Noadswood Science, 2016

2. Plant Cell Organisation & Specialisation
Wednesday, May 30, 2018
Plant Cell Organisation & Specialisation
To describe how cells are specialised for their function

3. Precise Learning
Meristem tissue in plants can differentiate into any type of plant cell, throughout the life of the plant.
Students should be able to explain how the structures of plant tissues are related to their functions (observation and drawing of a transverse section of leaf). Plant tissues include:
epidermal tissues
palisade mesophyll
spongy mesophyll
xylem and phloem
meristem tissue found at the growing tips of shoots and roots.
The leaf is a plant organ. Knowledge limited to epidermis, palisade and spongy mesophyll, xylem and phloem, and guard cells surrounding stomata.
Students should be able to explain how the structure of root hair cells, xylem and phloem are adapted to their functions.
The roots, stem and leaves form a plant organ system for transport of substances around the plant.
Xylem tissue transports water and mineral ions from the roots to the stems and leaves. It is composed of hollow tubes strengthened by lignin adapted for the transport of water in the transpiration stream.
Phloem tissue transports dissolved sugars from the leaves to the rest of the plant for immediate use or storage. The movement of food molecules through phloem tissue is called translocation.

4. Plant Cell
Draw a plant cell, labeling each of the key parts and identifying their function

5. Plant Cell Plant cells contain: - Cell membrane Cytoplasm Nucleus
Mitochondria
Ribosomes
Cell Wall
Vacuole
Chloroplasts
Cytoplasm
Ribosomes
Nucleus
Chloroplast
Cell wall
Vacuole
Cell membrane
Mitochondria

6. Functions Part Function Nucleus
Controls what happens in the cell (but it is not a ‘brain’)!
Cell Membrane
Controls what substances can enter and exit the cell
Cytoplasm
Where chemical reactions take place (jelly-like substance)
Mitochondria
Most of the cells energy is released here via respiration
Ribosomes
Protein synthesis occurs here
Chloroplasts (Plants only)
Where photosynthesis occurs (contain chlorophyll (which is green))
Vacuole
(Plants only)
Contains cell sap (a solution of sugar and salt) helping with rigidity
Cell wall
Made of cellulose, which gives support to the cell

7. The Leaf
Leaves are designed for one thing – making food via photosynthesis
Leaves are broad and flat to capture lots of light
Veins carry water to the leaf, and food away to the rest of the plant (veins also support the leaf)
Small holes called stomata in the underside of the leaf allow gases in and out

8. Leaf Components
There are specialised parts to a leaf which help with photosynthesis

9. Epidermal Cells & Waxy Cuticle
Cells in the epidermis make wax which covers the leaf surface (especially at the top) which limits water loss and acts as a protective barrier

10. Palisade Cells
These cells are full of chloroplasts (containing chlorophyll) which it where photosynthesis takes place

11. Spongy Mesophyll
This layer is full of air spaces which allows CO2 to reach chloroplasts in the palisade layer

12. Stomata
Stomata are tiny holes which allow CO2 into the leaf (they also allow water to escape)
The stomata are pores which open and close automatically controlled by guard cells
When there is lots of water they become turgid so the pore opens
When there is not much water they become flacid which closes the pore preventing water loss but it also stops CO2 getting in so photosynthesis stops too!

13. Xylem & Phloem
Xylem transports water and mineral ions from the roots to the stems and leaves – it is composed of hollow tubes strengthened by lignin adapted for the transport of water in the transpiration stream
Phloem transports dissolved sugars from the leaves to the rest of the plant for immediate use or storage – the movement of food molecules through phloem tissue is called translocation

14. Meristem Tissue
Meristem tissue is found at the growing tips of shoots and roots and is able to differentiate into lots of different types of plant cell
This allows the plant to grow

15. Photosynthesis

16. Practice Questions True or false – leaves are organ systems?
Name the plant tissue where photosynthesis occurs
What is the function of the air spaces in spongy mesophyll tissue?
Where in a plant is meristem tissue found?
Explain why the upper epidermis of a leaf is transparent

17. Answers True or false – leaves are organ systems – false
Name the plant tissue where photosynthesis occurs – palisade mesophyll tissue
What is the function of the air spaces in spongy mesophyll tissue – allow gases to diffuse in and out of cells
Where in a plant is meristem tissue found – in the growing tips of shoots and roots
Explain why the upper epidermis of a leaf is transparent – so light can pass through to the palisade layer which contains lots of chlorophyll for photosynthesis