Role of the Xylem & Phloem

Xylem

Plant tissue that transports water and mineral ions from roots to leaves

Phloem

Plant tissue that transports sugars and amino acids

Transpiration stream

Continuous flow of water through the xylem

Translocation

Movement of sugars in the phloem

Lignin

Substance that strengthens xylem walls

Sieve tubes

Phloem tubes that transport dissolved sugars

Companion cells

Cells that provide energy for phloem transport

Root hair cells

Cells that absorb water and minerals from the soil

Mineral ions

Nutrients such as nitrate and magnesium transported in xylem

Sucrose

Main sugar transported in phloem

What does the xylem transport?

Water and mineral ions

What direction does xylem transport occur in?

Upwards only

Why are xylem walls strengthened with lignin?

To prevent collapse under pressure

What does the phloem transport?

Sugars and amino acids

What direction does phloem transport occur in?

Up and down the plant

What is translocation?

Movement of sugars in the phloem

Why do phloem cells need companion cells?

To provide energy for active transport

What sugar is mainly transported in the phloem?

Sucrose

Why do plants need to transport sugars?

For respiration and growth

Why do plants need to transport water?

For photosynthesis and to maintain turgor pressure

Why do plants need mineral ions?

For healthy growth and making important molecules

Which tissue transports nitrate ions?

Xylem

Which tissue transports products of photosynthesis?

Phloem

Why is the xylem hollow?

To allow an uninterrupted flow of water

Why does the phloem have sieve plates?

To allow movement of dissolved substances between cells