9.1 Transport systems in dicotyledonous plants

Question 1

What are dicotyledonous plants?

Answer 1

they make seeds that contain two cotyledons (organs that act as food stores for developing embryos and form the first leaves when the seed germinates

Question 2

vascular bundle

Answer 2

A strand of primary conductive plant tissue consisting chiefly of xylem and phloem.

Question 3

vascular bundle in stem?

Answer 3

around the end of the stem to give strength and support

xylem on inside whilst phloem is on the outside

Question 4

vascular bundle in root?

Answer 4

vascular bundles are in the middle to help plant withstand the tugging strains as a result of stems and leaves being blown in the wind
–> star shaped xylem in centre and circular phloems in the remaining space

Question 5

Vascular bundle in leaf?

Answer 5

midrib of dicot leaf is the main vein carrying vascular tissue
- also supports structure of leaf

–> xylem on top, phloem under

Question 6

Structure of xylem

Answer 6

made of non-living tissue
–> long, hollow structures made by several columns of cells fusing together end to end

–> lignified secondary walls that provide mechanical strength

–> Thick-walled xylem parenchyma packs around the xylem vessels (storing food and containing tannin deposits

Question 7

What is tannin?

Answer 7

bitter, astringent-tasting chemical that protects plant tissue from attacks by herbivores

Question 8

Function of xylem vessels

Answer 8

transport of water and mineral ions from the roots

support for the plant

Question 9

Function of the phloem

Answer 9

transports food (products of photosynthesis) in form of organic solutes around the plants from leaves

–> phloem supplies cells with sugars and amino acids needed for cellular respiration and synthesis of all other molecules

–> flow of materials can go up and down

Question 10

Structures of the phloem

Answer 10

many cells joined to form hollow long structure (not lignified)

Walls become perforated to form sieve plates

Companion cells closely linked with sieve tube elements by many plasmodesmata

Question 11

sieve plate function

Answer 11

to connect and transport tissue in plants, allowing food to pass through the phloem tubes due to the tiny pores present on these tubes.

Question 12

plasmodesmata

Answer 12

conduits to allow the exchange of various cellular molecules between plant cells

Question 13

companion cell function

Answer 13

to provide essential molecules to sieve tube element cells

contain an nucleus and lots of mitochondria
–> move molecules like ATP and proteins can move through plasmodesmata into sieve tube elements