(b) structure and function of vascular system

What is a herbaceous dicotyledons

Contain seeds that have 2 seed leaves

Leaves have broad blades and stalks

Short life cycle

Soft tissues

What is a woody dicot

Hard and lit fried tissues and long life cycles

How are the V.B arranged in stem of herbaceous plant

V.B are around edge to give the stem strength and support

How is V.B arranged in roots of plant?

V.Bin the middle

Withstand tugging strains as stems and leaves blow in the wind

How is V.B looks in leaves

Helps support structure of leaf

Leaf is main vein with V.B

What is the xylem made of (2)

Non living tissue

Long hollow structures

What is the thick walled part of xylem called

XYLEM PARENCHYMA

Contains packs around vessels

Stores food + contain tannin deposits (chemicals that protects plant tissues from herbivores)

What other wall does the xylem have and why

LIGNIFIED SECONDARY WALL

• extra mechanical strength

• Doesn’t transport water

What does the secondary wall form?

Rings of spirals of tubes

Creates small undignified areas = bordered pits

What is the phloem made of

Living tissue

What is the function of phloem

Transports food in form of organic solutes

Supplies cell with sugars + amino acids for respiration and synthesis of useful molecules

What does the phloemand xylem have both in common in terms of structure

Both have extremely thick walls

What’s diffferent about the flow of what’s being transported in phloem vs xylem

The flow in phloem is up and down

Flow in xylem is just upwards

What are sieve tube elements structure

Made of many cells joined = hollow structure

Are sieve tube elements lignifed

NO SIEVE TUBE ELEMENTS ARE NOT LIGNIFIED

What is contained in sieve tube elements

Perforated walls between cells

Have large pores in cell wall > phloem flows through

What d the tonoplast and nucleus do in sieve tube elements

Tonoplast + nucleus - break down= phloem sap +fill phloem

Mature phloem cells = no nucleus

What is the structure of companion cells? Does it have a nucleus

Linked to sieve tube = forms with them

Have nucleus and organelles

What is the sieve tube element linked to the companion cell by

Plasmadesmota

What is the purpose of companion cell

Active

Life support system for sieve tube (which lost most of their normal cell functions)