Function shapes structure Structure enables function What functions

Function shapes structure… Structure enables function What functions and structures exist? Those passed on by past generations… Evolution

CB 35. 2 Plants grow and reproduce, as well as, respond to the environment.

Plants grow and reproduce, respond to the environment… today- transport

CB 35. 9 Types of Plant Cells: defined by function and cell wall

CB 6. 9

Parenchyma cells- most common cells; primary cell walls CB 35. 9 60 m

Parenchyma in a stem CB 35. 16

Collenchyma cells- unevenly thickened cell walls; flexible support CB 35. 9 80 m

Collenchyma in a leaf

Sclerenchyma cells- Thickened secondary walls (inside primary wall); with lignin; rigid 5 m 25 m CB 35. 9

Water conducting cells of Xylem: vessels and tracheids (types of sclerenchyma) CB 35. 9 100 m

Sugar conducting cells of Phloem: sieve-tubes and companion cells CB 35. 9 30 m 15 m

CB 35. 18 Plants transport water, sugar, minerals, hormones, etc through the vascular system comprised of xylem and phloem

CB 36. 2 Water travels from ground out through stomata via xylem

CB 36. 2 The exit of water through stomata is accompanied by gas exchange

CB 36. 2 Sunlight powers photosynthesis and these sugars are transported via phloem

The direction of Phloem transport is versatile.

Plant cell to cell transport can occur by two pathways: symp[lastic and apoplastic CB 36. 8 plasmodesmata

Sugar is loaded at sources and unloaded at sinks CB 36. 17

CB 36. 18 Sugar is loaded at sources and unloaded at sinks source: leaf sink: root, flower, emerging leaf etc…

CB 35. 18 Plants transport water, sugar, minerals, hormones…

CB 36. 7 Much of plant support comes from turgor pressure.

CB 36. 13 Water moves from the ground through roots into the shoot and out stomata in the leaves.

CB 35. 12 and. 13 In roots the vascular bundle is in the center

CB 36. 9 The casparian strip of the endodermis keeps water from entering the xylem via a purely apoplastic route.

CB 36. 13 What moves the water through the xylem?

CB 35. 17

Stomata control entry of CO 2 and exit of H 2 O from plant leaves CB 36. 12 Stomata

Stomata on the underside of a leaf

CB 36. 15 Guard cell opening is regulated by turgor

CB 36. 13 What moves the water through the xylem? Transpiration, Adhesion, Cohesion, and Tension

water transport limits plant growth

More xylem is needed for more water transport: secondary growth phloem xylem

Xylem is tough, and full of lignin- inhibits the ability to use plants to produce biofuels phloem xylem