dicotyledonous plants-transport in plants

Question 1

what are dicotyledonous plants/dicots

Answer 1

• 2 types, herbaceous dicots and woody (arborescent) dicots
• make seeds that contain 2 cotyledons, organs that act as food stores for the developing embryo plant and form the first leaves when the seed germinates

Question 2

3 main reasons why multicellular plants need transport systems

Answer 2

• metabolic demand, many internal and underground parts of the plant do not photosynthesise=need glucose and 02 transported to them + waste products removed. Mineral ions need to be transported
• size, larger=need transport system
• SA:VOL, the size and complexity of the stems/ trunks etc means there is a small SA:VOL ratio=cannot rely on diffusion

Question 3

structure + function of xylem

Answer 3

• transports water and mineral ions, made up of mainly dead cells
• thick walled parenchyma packs around the xylem vessels, storing food and containing tannin droplets (tannin protects plants tissues from attack f=by herbivores
• lignified secondary walls

Question 4

structure and function of phloem

Answer 4

• living tissue that transports food in the form of organic solutes around the plant from the leaves
• flow goes both up and down the plant
• main transport vessel=sieve tube elements
• phloem tube not lignified
• sieve plates between the elements, let phloem contents through
• companion cells formed next to the sieve tube elements, linked via the plasmodesmata
• companion cells have nucleus