Water enters plants in the roots via osmosis

Click through the following slides to learn how water enters plants in the root.

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Uptake of Ions by the Roots

Root hairs uptake a variety of essential mineral ions, for example:

• Ca2+
• Mg2+
• K+
• Na+

Water Transport into the Roots

• Root hairs and branching greatly increase the surface through which water and dissolved minerals can be absorbed.

Uptake of Ions by the Roots

Uptake of ions from the soil usually takes place against a concentration gradient (active transport, uses a PUMP protein and requires ATP)

Roots are HYPERTONIC to soil

Soil is HYPOTONIC to roots

Hypertonic = has higher concentration of solutes

Hypotonic = has lower concentration of solute

Because ions are actively transported into roots,

the roots end up having a higher solute concentration compared to the surrounding soil.

Water moves from hypotonic to hypertonic, so water moves from the soil into the root.

This is PASSIVE (no energy) OSMOSIS.

Hypertonic

Hypotonic

Once water is inside the root, it moves to the plant xylem in one of two ways:

SYMPLASTIC PATHWAY

APOPLASTIC PATHWAY

Water Transport into the Roots

• Apoplastic transport is when water is transported between cells through the extra-cellular space.

Water Transport into the Roots

• The transport of water within cells cytoplasm via plasmodesmata is called symplastic transport.

Water Transport into the Roots

• Plant are usually interconnected via plasmodesmata.

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• Their plasma forms a continuum (a “symplast”).