Transport in Plants

Title: Transport in PlantsLesson objective:

1.Can I explain the role of vascular tissue? Grade C/B

2.Can I describe the distribution of vascular tissue in plants? Grade D/C

Starter: Name specialized cells in the plant and what their roles are….

Root hair cell

Epidermal layer with root hair cells – increase surface the area.

Absorb minerals by active transport and water by osmosis from the soil.

Vascular tissue in Roots…

Vascular tissue in Stems…

Sclerenchyma tissue

Phloem

Cambium

Xylem

Vascular tissue in Leaves

Xylem…Tissue – tubes with no end walls, fibres and parenchyma cells.

Xylem vessels – long dead cells (empty) with thick walls (lignin) and pits.Lignin – waterproofs cells, strengthens the vessels, forms patterns (allows flexibility).

How is xylem adapted to its function?

PhloemTissue – sieve tube elements and companion cellsSieve tubes – little cytoplasm and no nucleus, lined up, cross walls that are perforated (sieve plates).

Companion cells – large nucleus and dense cytoplasm, mitochondria (metabolic processes), plasmodesmata (links).

To do…Microscope work – make schematic

diagrams of the root and stem, fully labelled.

Title: Transpiration

Lesson objective:

1.Can I describe how transpiration occurs and how to measure it? Grade C

2.Can I explain transpiration and what could affect the rate ? Grade B/A

Starter: Identify the plant organ and add the labels in….

Homework: Notes on xylem and phloem….

Specialised tissues…

In your groups – make a mini-factfile on one of the three tissues: xylem, phloem or stomata…

You can:• Use your mobile phones – video your

fact file• Use the paper provided to make a

‘leaflet’

You have 10 minutes…..

Stomata

Pathway of water:Xylem bring water to leaf,

Passes to mesophyll cells by osmosis,

Water evaporates from surface of mesophyll cells to the air spaces as water vapour,

Water vapour collects (higher potential) and so diffuses out of the leaf.

Exam question

Transpiration…Transpiration is

the loss of water vapour from the leaves.

Involves 3 processes:• Osmosis from

xylem to mesophyll cells

• Evaporation • Diffusion of water

out the stomata

The potometer

Title: Transpiration

Lesson objective:

1.Can I describe the factors that affect the rate of transpiration? Grade C

2.Can I explain how plants reduce water loss? Grade B/A

Starter: Exam question….

Transpiration stream…

Useful to plant:• Water is needed in leaves for

photosynthesis• Water is needed for cells to grow and

elongate• Keeps cells turgid• Flow of water carries useful minerals• Evaporation keeps plant cool

Factors affecting transpiration..

Number of leavesNumber, size and position of stomataCuticleLightTemperatureHumidityAir movementWater availability

Reducing water loss…

Unavoidable….Plants exchange gases via stomata

during the day.How to reduce loss?Waxy cuticleStomata found on undersurface of leafStomata close at nightLoss of leaves

Exam question

Loss of too much water…?

Xerophytes…Plants that are adapted to living in

dry/arid conditions – they are able to reduce water loss from leaves in numerous ways….

Rolled leaf – lower epidermis is not exposed.

Thick waxy cuticle

Trapped air in centre with high water potential

Hairs reduce movement of air

Stomata in pits to trap air with moisture