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Flashcards in Phloem translocation Deck (53):
1

phloem transports products of photosynthesis from

mature leaves to areas of growth and storage

2

phloem conducts -- molecules

signal

3

phloem -- water

redistributes

4

phloem extends throughout the plant body and is -- with xylem

parallel

5

in trees with secondary growth, the phloem is on the outside of the -- and only the inner layer of phloem is functional as outer is crushed by xylem

vascular cambium

6

phloem is removed by removing bark

girdling

7

girdling tree -- ceases between root and leaves

sugar transport

8

sieve tube elements

angiosperms

9

sieve cells

gymnosperm

10

store and release food molecules

parenchyma cells

11

protection and strengthen tissue

fibers and sclereids

12

sometimes -- (latex containing) for protection

laticifers

13

only -- are directly involved in translocation

sieve elements

14

small veins of leaves and primary vascular bundles of stems are typically surrounded by a -- which are compactly arranged colorless cells isolating the veins from the intercellular spaces of the leaf

bundle sheath

15

mature sieve elements contain

mitochondria, plastids, smooth ER

16

sieve element's cell walls are -- and thus remain soft and flexible

non-lignified

17

where pores connect to the other sieve elements

sieve areas

18

pore range from

less than 1 to 15 micro m

19

in angiosperms, sieve areas on the end walls can differentiate into -- with larger pores and

sieve plates

20

sieve tube elements can connect to form --

sieve tubes

21

in gymnosperms, -- cover the sieve areas

smooth ER

22

dive cells contain sugars and organic molecules in a fluid solution

sap

23

sieve tube elements also contain -- which are tubular, fibrillar, granular, or crystalline

P proteins

24

P proteins seal damaged sieve elements by plugging off --

sieve plate pores

25

relatively few plasmodesmatal connections to cells except its own sieve element; symplastically isolated from surrounding cells

ordinary companion cells

26

finger-like wall ingrowths of cell walls facing away from the sieve tube elment

transfer companion cells

27

many plasmodemsata connections with bundle sheath cells, well-suited for taking up solutes via cytoplasmic connections

intermediary companion cells

28

ordinary companion cells -- loading

apoplastic

29

transfer companion cells -- loading

apoplastic

30

intermediary companion cells -- loading

symplastic

31

sources are typically mature leaves; others include storage organs --

storage root of beets

32

sinks = -- organs including roots, developing flowers and immature leaves

nonphotosynthetic

33

phloem sap can be collected using -- natural syringes

aphid stylets

34

most abundant substance in phloem

water

35

sugar in phloem are --

nonreducing

36

typical range of phloem sap

30 cm to 1.5 m per h

37

pressure gradient of bulk flow is established by

loading and unloading of sugars into sieve tubes

38

sieve plate -- slows equilibration allowing a standing pressure gradient to exist and to drive flow

resistance

39

sucrose moves from producing mesophyll cells to cells adjacent to the sieve elements in the leaf minor veins, only a few cell diameters

short distance transport pathway = symplastic

40

sugars are transported into the sieve elements and companion cells

phloem loading

41

sugars are translocated away form the source via

long-distance transport

42

-- loading requires energy

apoplastic

43

H+-ATPase transports H+ into the apoplast and a -- transport sucrose form the apoplast into the sieve element-companion cell complex

sucrrse H+ symporter

44

explains how different solute concentrations can be generated in different adjacent cells connected by plasmodesmata

polymer-trapping model

45

sucrose synthesized in the mesophyll diffuses form the bundle sheath cells into the -- via small plasmodesmata

intermediary cells

46

In the intermediary cells, -- and -- are syntehsized

raffinose and stachyose

47

larger raffinose and stachyose diffuse through the larger plasmodesmata to the --

sieve element

48

-- loading can also occur given high enough sugar production rates

passive

49

in dev leaves, first whole leaf is a sink and sugars are unloaded from the -- in the unexpanded leaf

major veins

50

as leaf matures, major veins spaced apart and -- dev between them

minor veins

51

when unloading ceases and loading begins only in --

minor veins

52

signal molecules are -- from sources

loaded

53

GFP expressed in -- cells to show loading and unloading

companion cells