Transport in plants and structure of vessels Flashcards

1
Q

what is a phloem

A

a tissue used to transport assimilates

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2
Q

What is a xylem

A

a tissue used to transport water and minerals

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3
Q

Why do plants need a transport system

A

to meet their high metabolic demand for o2, water, minerals etc..

to compensate for their small sa: vol ratio (large plants)

plants cant rely on diffusion alone.

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4
Q

What direction does water and minerals travel in the xylem

A

Upwards

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5
Q

What direction do assimilates travel in the Phloem

A

Up and Downwards

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6
Q

What is a dicotyledonous plant

A

plants with two seed leaves and branching veins in leaf

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7
Q

what two types of tissue also give strength to the vascular bundle

A

Collenchyma
Sclerenchyma

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8
Q

what is a tap root

A

the thick main root of a plant

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9
Q

what is the pericycle and what is it made of

A

The pericycle is a thin layer of plant tissue between the endodermis and phloem.
Made of meristem tissue

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10
Q

What is the function of the vascular cambium

A

Vascular cambium- pushes the xylem and phloem apart.

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11
Q

Name a b c and d

A

A- Collenchyma
B- Parenchyma
C- Vascular cambium
D-pith

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12
Q

What is the function of lignin in xylem

A

Impregnates the walls of the xylem, killing cells and making them waterproof

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13
Q

How does lignin cause long collums of xylem

A

Lignin kills the cells in the wall. The end walls and contents of cell begin to decay.
Causing a long column with dead cells and no contents.

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14
Q

How does lignin help the xylem to stay open

A

The lignin prevents xylem collapsing and keeps it open. Also provides flexibility to the stem/branch

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15
Q

What shape is lignin in the xylem

A

Spiral rings

or could be broken rings

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16
Q

How are bordered pits in the xylem formed

A

Lignification is incomplete. Leaving gaps in the cell wall making bordered pits.

17
Q

What do bordered pits do (xylem)

A

Allow water to leave 1 vessel and pass into the next vessel

18
Q

A xylem vessel can sometimes be paired with a “xylem parenchyma”, what are the two functions of this

A
  • contain food stores to enable xylem to repair if necessary or grow

-contain tanin which is bitter, herbivores taste tanin and prevent herbivores eating plant

19
Q

what direction does phloem move

A

source to the sink

20
Q

what direction does water in xylem flow

21
Q

why does the phloem transport sucrose rather than glucose

A

more stable form of sugar, not as easily used up

22
Q

which vessel is alive? xylem or phloem

A

Phloem, to perform active transport in translocation.

23
Q

what are the name of the individual segments of the phloem vessel

A

Sieve tube elements

24
Q

what structure is interlinked to the side of a xylem

A

Companion cell

25
Between the Companion cell and phloem, there is plasmodesmata, what does the plasmodesmata allow to happen.
Allows substances to flow through the two cells
26
describe the organelles in the sieve tube elements
very little cytoplasm, no nucleus to leave space for mass flow of sap
27
what is an advantage to the xylem vessel being narrow
it prevents the water column breaking
28
why is it beneficial for there to be cohesion and tension in the xylem to pull the water upwards
because the water can be pulled upwards to replace the water lost by transpiration