1. From Cell to Organism: Focus on Plants
Section 9.1
Science 10

2. Learning Outcomes By the end of this section you should be able to…
describe why multicellular organisms need a level of organization to survive
describe how leaf cells of plants have specialized structures and functions
explain the gas exchange system in plants
explain the transport system in plants
describe phototropism and gravitropism

3. Unicellular vs Multicellular Organisms
Unicellular Organisms
Multicellular Organisms
All life processes occur in a single cell
Large surface area to volume ratio
Short life
BENEFITS
DOWNFALLS
Contain specialized cells that perform specialized functions
Small surface area to volume ratio
Longer life

4. Multicellular Organisms Specializations:
Animal Cells
Perform specific tasks:
Muscle cells
Nerve cells
Skin cells
Blood cells
Plant Cells
Perform specific tasks:
Root cells
Stalk cells
Leaf cells
Vascular cells

5. Organization of a multicellular Organism (plant or animal):
Cells - perform a specific job
Tissues - group of specialized cells working together
Organs - tissues contributing to the same function
Organ System - group of organs working together

6. Plants have two organ systems Above Ground
Plant Organ Systems
Plants have two organ systems
Above Ground
The shoot system: stem, leaves, buds, flowers, fruits & tubers
Below Ground
The root system: tap root, lateral roots & surface roots
Students just write down the names of the two systems and whether they are above or below ground. More to come later.

7. Plants have three kinds of tissues:
Dermal Tissue = Skin (or epidermis)
Ground Tissue (mesophyll and palisade)
Vascular Tissue = Circulatory (xylem & phloem)
More to come later on these…

8. Cell Specialization in leaves
Leaves are specialized to do Photosynthesis:
carbon dioxide + water oxygen + glucose
6CO2(g) + 6H2O(l) O2(g) + C6H12O6(s)
Suns energy
chlorophyll
Glucose is a carbohydrate used for energy in both plant and animal cells
Oxygen gas, essential for both plants and animals, is produced as a by-product

9. How come plants can do Photosynthesis:
Plants contain an important organelle that animals do not:
CHLOROPLASTS
Chloroplasts contain a pigment called CHLOROPHYLL
traps light energy to drive the reaction

10. How do plants release energy from Photosynthesis?
Cells Burn Glucose = Carbohydrate
Source of energy (for all cells!)
Glucose = C6H12O6

11. Cellular Respiration
To obtain energy to fuel the cell’s activities a second general reaction is required. This process is cellular respiration
Occurs in the Mitochondria

12. 6O2(g) + C6H12O6(s) 6CO2(g) + 6H2O(l)
oxygen + glucose carbon dioxide + water
6O2(g) + C6H12O6(s) CO2(g) + 6H2O(l)

13. Next Steps Cell Specialization in Organisms P. 320-324 of your text
Label the specialized cells in a leaf
Review Photosynthesis & Cellular Respiration

14. Plant Structure and Function
Label your diagram of the cross section of a leaf (pg. 321 in your textbook)
We will fill in the function in a minute

15. More on Plant Structures & Function
Epidermal Cells
Sponge Tissue Cells
Stomata & Guard Cells
Palisade Tissue Cells
Vascular Tissue Cells

16. Epidermal Cells Epidermis
Covers the upper and lower surfaces of the leaf
The cuticle is a waxy layer that coats the upper epidermis to prevent evaporation of water from the leaf
protect the cell
They are transparent to allow solar energy to pass into the leaf

17. Palisade Tissue Cells The next layer down from the epidermis
packed with chloroplasts
where most of the leaf’s photosynthesis occurs
They are long & narrow which allows them to pack closely together, therefore very efficient

18. Spongy Tissue Cells contain chloroplasts and carry out photosynthesis
The layer below the palisade tissue cells
These cells are round and loosely packed. Air spaces are between them, like a SPONGE
exchange gases and water

19. Stomata pores in the leave which allows gases in and out
They are embedded with in the lower epidermal layer
CO2 in and O2 and H2O out

20. Guard Cells Each stoma is flanked by guard cells
Regulate the stoma’s size
Open and closes the stomata

21. Science 10, Plants Science
14-Sep-18
Page 309.
Mitchell, 2004

22. Vascular Tissue Cells tubes that act as leaf veins transports fluids
xylem – carries water and minerals from the roots to the leaves
phloem – carries sugars made by the leaf to various parts of the plant

24. Science 10, Plants Science
Features of the leaf.
Science 10, Plants Science
14-Sep-18
palisade mesophyll
vascular bundle
--point out upper and lower epidermis
--in the vascular bundle, the xylem is the pink stuff on top, in rows of “holes” and the phloem is the tiny blue/purple stuff underneath
--under the phloem are dark pink rings. These are a supportive structure called “collenchyma”. FYI only; science 10 doesn’t need to know collenchyma.
spongy mesophyll
guard cells and stoma
Mitchell, 2004

25. Science 10, Plants Science
14-Sep-18
Leaf Features
This leaf is from a plant adapted to survive in dry weather. It looks somewhat different from the previous leaf, but they both have similar features. Can you spot them? Look for dermal, ground and vascular tissues.
Mitchell, 2004

26. Science 10, Plants Science
14-Sep-18
cuticle
upper epidermis
palisade mesophyll
vascular bundle
spongy mesophyll
air spaces
Teacher Info:
Thickened, waxy cuticle present on upper surface. It is transparent.
In this picture, the upper epidermis is 3 layers thick, and stained red in colour.
Two layers of palisade mesophyll.
Difficult to make out the xylem and phloem in the bundle because it’s so tiny. Xylem is likely located facing the top of the leaf.
Stomata are located in depressions that shelter pores from dry wind. May be surrounded by hairs.
Reduced number of stomata.
Stomata located on lower epidermis only.
Lower epidermis is a few cell layers thick and stained red.
guard cells
(stoma is closed)
lower epidermis
Mitchell, 2004

27. To Do:
Read pages
Photosynthesis & respiration in plants (BLM9-1) on back side of leaf diagram.