Xylem and Phloem adaptation

Question 1

Structure and function of xylem

Answer 1

• Xylem is non-living and it transports water and mineral ions and provides support for plant.
• Long, tube-like structures formed from cells joined end-to-end. No end walls creates an uninterrupted tube that allows water to pass easily.
• Cell walls are thickened by spirals of lignin which stops them collapsing inwards.
• Parenchyma packs around xylem which has tannin - a foul tasting chemicals to prevent attacks from organisms.

Question 2

Observing xylem vessels

Answer 2

1) Place plants such celery stalks in strongly dyed water for 24h.
2) Remove plant and rinse.
3) Make transverse cuts along stem and Xylems should show up as coloured spots.
4) Make longitudinal cuts across a stem and Xylem should show up as coloured lines.

Question 3

Function of phloem

Answer 3

• Living tissue that transports solutes such as sugars around the plant from leaves where its made by photosynthesis.
• Phloem supplies cells w/ sugars and amino acids needed for respiration and synthesis.
• Flow of minerals go up AND down the plant.

Question 4

Structure of phloem

Answer 4

• Main transporting vessels are sieve tube elements which are formed by cells joined end to end to form long hollow structures.
• But the end walls are perforated to form sieve plates that lets phloem content through.
• Sieve tube elements have no nucleus, v thin layer of cytoplasm and few organelles.
• Companion cells are linked to sieve tube elements by plasmodesmata.
• They carry out all living functions and are very active.