Transport systems in dicotyledonous plants

Question 1

What are Dicotyledonous (Dicot) plants?

Answer 1

• A plant which has seeds made of two parts.

Question 2

Why are transport systems needed in multicellular plants?

Answer 2

• High metabolic rate: exchange via direct diffusion would be too slow to meet their metabolic needs.
• Relatively big in size: need an effective transport system to move substances both up and down from roots to leaves.
• Small surface area to volume ratio: cannot rely on diffusion alone

Question 3

Transport systems

Answer 3

• Plants have a vascular system: series of transporting vessels running through roots, stems and leaves.
• In herbaceous dicots this is made of xylem and phloem vessels.
• These transport tissues are arranged as vascular bundles.

*TS= Transverse crosssec.

Question 4

Stem diagrams

Answer 4

• Xylem and phloem are near the outside to provide strength and support to reduce bending.
• Phloem is on the outside, xylem on the inside.
• Cambium between xylem and phloem.
• Phloem + cambium + xylem makes up vascular bundles.
• LONGITUDINAL: phloem on outside and xylem on inside

Question 5

Root diagrams

Answer 5

• Xylem and phloem in the centre to provide support for the root and to help plant withstand strains due to stems and leaves being blown by wind.
• Circle in the middle protecting vascular bundle is Endodermis.
• Xylem is arranged like a plus sign and phloem is between right angles;

Question 6

Leaf diagrams

Answer 6

• The middle of the leaf is the main vein carrying vascular tissues. This helps support the leaf.
• Xylem facing the top of leaf and phloem at bottom.