For this IBDP Biology post, we will be looking into the adaptations of leaves and the tissue distribution of the roots that helps with water absorption, let's get to it!

Absorption of Water in the Roots  

• Higher concentration of mineral ions in root hair cells than in soil. Plants still absorb more from the soil using Active Transport
• Root hair cells have mitochondria and protein pumps for Active Transport
• The root hair cells have a higher solute concentration than soil therefore water moves into the plant by osmosis
• The branching of roots and growth of root hair cells allows for an increase in surface area
• Roots only absorb if oxygen is present so that ATP can be produced for Active Transport  

Adaptations of Desert Plants to absorb Water  

Xerophytes - Desert Plants

• Plants in dry habitats are adapted to reduce transpiration for water conservation
• Verical Stems: Allow sunlight to be absobed early and late in the day
• Thick Cuticle: Thick waxy cuticle which covers the stem
• Spines (not leaves): Reduces surface area of transpiration
• Open stomata at night: Opens at night and not during day when heat is most intense

EXAMPLE: Marram Grass

• Thick waxy cuticle
• Smaller air spaces in spongy mesophyll
• Few stomata and stomata are within pits
• Cells change shape: Leaves roll up so that the lower epidermis and stomata are on the inside  

Adaptations of plants in Saline Soils to absorb Water

Halophytes - Plants in Saline Soils

In coastal habitats and arid (no water) areas

• Water moves up the soil and then evaporates this leaves dissolved ions at the surface
• Most plants cannot grow in these conditions only Halophytes are able to

Keep in Water

• Solute concentration is higher in plant than soil
• DO NOT rasie  only maintain sodium concentration in vacuole - affects cell activities
• Raise concentrations of other solutes (potassium) maintained in cytoplasm
• Water can also be conserved in water storing tissues: Succulents

Get rid of Sodium

• Active Transport
• Excretion from special glands within the leaves
• Accumulate the ion in certain leaves and then shed the leaf  

That's all!

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References:

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