Settler Xylem exam question

Module 2 Exchange and transport 1.2.15 Plant cells and water

Starter ψ What does this symbol mean?

Learning Objectives Success Criteria Explain, in terms of water potential, the movement of water between plant cells and between plant cells and their environment Define water potential (Grade E) Define the three pathways that water can take through cells (Grade D – C) Describe in terms of water potential, the movement of water between plant cells and plant cells and their environment (Grade C –B) To predict the pathway that water will travel through the cells , using diagrams (Grade B – A)

Water potential Using your knowledge from KS4 and your understanding of water potential write down how water travels into a root. (remember a plant cells cytoplasm contains some salts and sugars) Swap your work with your neighbour and peer assess Define water potential (Grade E)

Osmosis and plant cells Boardworks GCSE Additional Science: Biology Movement In and Out of Cells Osmosis and plant cells Jan 11 question 6 past paper Teacher notes This activity could be used to check students’ understanding of the effects of osmosis on plant cells.

Tasks Using diagrams from previous slides and information explain what happens to a plant cell when placed in (a)pure water (b) Solution of very low water potential (concentrated salt solution) Jan 11 question 6 past paper

Plenary - SA SA previous exam question – show of hands

Why does water enter a root? Down a water potential gradient How is this created? By the active transport of minerals into the root.

As water enters the root hair cell, this raises its water potential, so it is now higher (less negative) than that of its neighbouring cell. This means water passes from the root hair cell to the cortex cell next to it. This process is repeated across the root, until the water enters the xylem.

The 3 pathways for water to move through the root of a plant

Pathways through the root 1)Symplast pathway – goes through living parts of cells – cytoplasm. The cytoplasm of neighbouring cells connect through plasmodesmata (small channels in cell walls) 2)Apoplast pathway – goes through non-living parts of cells-cell wall 3)Vacuolar pathway – similar to symplast but it can enter the vacuoles as well Define the three pathways that water can take through cells (Grade D – C)

Water can only cross the root by the apoplast pathway until it meets the endodermis!!!

Why is the endodermis and Casparian strip – the end of the apoplast pathway? Suberin in the Casparian strip stops water and mineral ions continuing along the apoplast pathway, so they have to enter the cytoplasm, through the cell membrane, taking the symplast pathway.

Movement of water Pathways worksheet

Transport through the root www.youtube.com/watch?v=TWNtXw-MWtE Label pathways on your root hair structure Explain the vacuolar pathway Describe in terms of water potential, the movement of water between plant cells and plant cells and their environment (Grade C –B) To predict the pathway that water will travel through the cells , using diagrams, (Grade B – A)

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