Transport in Living Things Chapter 25 Chapter 25.5 Transport System in Flowering Plants

What did we learn? Transport of mineral salts into the roots Movement of substances Passive process Active process Active Transport Diffusion Osmosis Movement of molecules from a region of lower concentration to a region of higher concentration with the use of energy Transport of mineral salts into the roots Add video: how osmosis works Net movement is the overall direction of a movement of a substance Net movement of molecules from a region of higher concentration to a region of lower concentration Transport of water into roots Net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane Carbon dioxide and oxygen inside leaves Gaseous exchange in the lungs

Lesson Objectives At the end of the lesson, You should be able to: State what the vascular bundle consists of Describe the structure and function of xylem and phloem Identify the position of xylem vessels and phloem in sections of the stem relate the structure and functions of root hairs to their surface area, and to water and ion uptake identify the positions of xylem vessels and phloem in sections of a typical dicotyledonous stem and leaf, under the light microscope, and state their functions relate the structure and functions of root hairs to their surface area, and to water and ion uptake state that transpiration is the loss of water vapour from the stomata

Looking at the rose… How do you turn a white flower into a blue one? How does the coloured water travel up the stem to the flower?

Vascular tissues Xylem Phloem

Xylem tissue Structure Function composed of hollow, nonliving cells (continuous lumen) Lignified walls Function transports water and mineral salts from roots → stem → leaves provides mechanical support to plant

Structure of Xylem

QUESTION How is the straw similar to the xylem?

Phloem tissue Structure Living cells Function Transports manufactured food (sucrose and amino acids), usually from leaves → other parts of the plant

Identifying a vascular bundle

Identifying a vascular bundle in a dicotyledonous stem

A vascular bundle cambium

Transverse section of a stem

Why do you think the xylem is positioned on the inside?

How to distinguish xylem vessels from phloem in microscopic slides? Xylem vessels have Thicker walls - due to lignified walls (either annular, spiral or pitted) to provide mechanical support to the plant Larger lumen compared to phloem Xylem vessels have a darker stain.

Locate the xylem and phloem

Leaf structure xylem phloem

Transport of water

Structure of root Function of root Presence of Root hairs Increased surface area Function of root Absorb water and mineral salts from the surroundings Water absorbed from the root enters the xylem

Entry of water into the plant Thin film around particle = dilute solution of mineral salts

Entry of water from soil Plasma membrane of root hair cell Sap in root hair Soil solution Strong solution of sugars and salts Dilute solution of mineral salts H2O Low water potential Higher water potential Osmosis

Transport of water from root hair → xylem

High water potential Low water potential

Transport of mineral salts 25

Transport of mineral salts Plasma membrane of root hair cell Sap in root hair Soil solution Mineral concentration low Mineral concentration high Mineral salts Diffusion 26

Transport of mineral salts Qn: Can the root hair absorb ions if the concentration is higher in the root hair sap compared to the soil solution? Yes!!! Plasma membrane of root hair cell Sap in root hair Soil solution Mineral concentration high Mineral concentration low Mineral salts? Active transport 27

Summary Plant Transport system Consists of Xylem Phloem transports Water containing dissolved mineral salts from the roots to the leaves Manufactured food substances (eg. sugars) from the leaves to the other parts of the plant Mineral salts move into the root hair cell via Diffusion OR ACTIVE TRANSPORT where Water moves into the root hair cell via OSMOSIS

In the next lesson… We will be learning about what is transpiration what is translocation MINI QUIZ!