Lecture 4: Vascular system, to fetch a pail of water

Question 1

Are parenchyma cells alive at maturity?

Answer 1

yes

Question 2

Are collenchyma cells alive at maturity?

Answer 2

yes

Question 3

Are scelernchyma cells alive at maturity?

Answer 3

No

Question 4

What are the functions of parenchyma

Answer 4

photosynthesis
regeneration
secretion
storage

Question 5

What is the functions of collenchyma

Answer 5

supports the plants growing organs; as it is able to develop thick flexible walls

Question 6

What is the function of sclerenchyma?

Answer 6

strengthens and supports plant organs that are no longer growing

Question 7

What does it mean by vascular system?

Answer 7

transports nutrients throughout a plant

- such transport may occur over long distances more than 100m in the tallest plants

Question 8

What are the properties of water

Answer 8

surface tension
adhesion
cohesion

Question 9

What are the three stages of water transport in a tree

Answer 9

1. ) water uptake of soil (roots)
2. ) cohesion and adhesion in the xylem (trunk)
3. ) transpiration (leaves)

Question 10

How is the vascular system formed?

Answer 10

from the meristematic cells in young shoots and roots

Question 11

What must divide to make xylem and phloem?

Answer 11

procambium

Question 12

Where is the phloem located? outside or inside?

Answer 12

outside

Question 13

Where is the xylem located? outside or inside

Answer 13

inside

Question 14

Where does wood come from? xylem or phloem

Answer 14

xylem

Question 15

what does the vascular system supply to the plant

Answer 15

water
minerals
sugars

Question 16

What hormones are required for the development of xylem and phloem from the procambium

Answer 16

auxin and cytokinin

Question 17

What is the function of the xylem?

Answer 17

conducts..
water and minerals absorbed from the roots upwards 
- principal water conducting tissue
- also conducts minerals
- contains cells that store food

Question 18

What kind of tissue is the xylem (simple/complex?)

Answer 18

complex

Question 19

true or false; the xylem makes continuous pipes?

Answer 19

true

Question 20

What are the organisation types of xylem?

Answer 20

vascular bundles

vascular cylinders

Question 21

Which is made first the metaxylem or the protoxylem?

Answer 21

protoxylem

Question 22

true or false; the protophloem is crushed against the side of the epidermis of the plant because the xylem continues to increase in girth

Answer 22

true

Question 23

What are the 3 cell types that the xylem is composed of?

Answer 23

tracheary elements
fibers
parenchyma

Question 24

What do the tracheary elements do?

Answer 24

water conduction

Question 25

What do fibers of the xylem do?

Answer 25

storage and support

Question 26

What do the parenchyma of the xylem do?

Answer 26

storage

Question 27

What are the types of tracheary elements?

Answer 27

tracheids | vessels

Question 28

What are the characteristics of tracheary elements?

Answer 28

dead at maturity long, narrow cells have lignified secondary cell walls confer strength and rigidity

Question 29

What is the first type of tracheary elements formed?

Answer 29

protoxylem (rings/ annular thickenings)

Question 30

What is the second type of tracheary elements formed?

Answer 30

metaxylem (spiral or reticulate thickenings)

Question 31

Describe tracheids (all vascular plants)

Answer 31

pits in side walls sealed at ends water passes across cell sides

Question 32

What are vessels (angiosperms)

Answer 32

shorter than tracheids perforations at end of walls as well as pits at sides PERFORATIONS HAVE NO SECONDARY OR PRIMARY CELL WALL vessel may comprise several cells end on end water moves freely in continuous tubes pits are also present

Question 33

Why do vessels need perforations?

Answer 33

during hot/windy weather; rapid transpiration

Question 34

What are the downsides of using vessels to conduct water?

Answer 34

- susceptible to embolisms (pockets of air & water vapour) | - embolisms break the cohesion of water molecules (cavitation)

Question 35

What are the effects of embolism?

Answer 35

break the continuity of water in xylem - perforation contain air bubbles - and water moves sideways through pits and continues upwards

Question 36

What is apoptosis?

Answer 36

programmed cell death

Question 37

how is the water transported up a plant? What physical changes must occur?

Answer 37

- root pressure (push) | - transpiration stream (pull)

Question 38

How is transpiration increased?

Answer 38

eg. at noon the rate of transpiration increases as it is hotter

Question 39

What happens at night?

Answer 39

- at night, transpiration is low; root cells continue to pump mineral ions into xylem of the vascular cylinder; lowering the water potential

Question 40

Where does water flow in?

Answer 40

flow in from the root cortex | - generating root pressure

Question 41

What does root pressure sometimes result in?

Answer 41

guttation

Question 42

What is guttation

Answer 42

the exudation of water droplets on tips of grass blades or the lead margins of some small, herbaceous eudicots

Question 43

What are the functions of the phloem?

Answer 43

- principal food conducting tissue; many succrose; other sugars eg. mannitol, sorbitol; amino acids, micronutrients, lipids - major signaling superhighway (hormones,protein, RNA) - transport up to 1m/hr in either direction - osmotic pressure drives flow - links all other cells

Question 44

How does the phloem conduct the assimilate (food)

Answer 44

source to sink

Question 45

What is a sugar source?

Answer 45

- is a plant organ that is a NET PRODUCER of sugar, such as mature leaves

Question 46

What is a sugar sink?

Answer 46

- is an organ that is a net consumer or storer of sugar, such as tuber or bulbs, fruits, roots and shoots

Question 47

What is an assimilate?

Answer 47

food | - must be transported from mature leaves to growing points( roots, shoots, fruits)

Question 48

How is the plant body regulated?

Answer 48

regulation signals are transported via the growing points

Question 49

What are the 3 cells of the phloem

Answer 49

sieve elements sclerenchyma parenchyma

Question 50

What is the main function of the sieve elements of the phloem?

Answer 50

food conduction

Question 51

What is the main function of the sclerenchyma of the phloem

Answer 51

support

Question 52

What is the main functionof the parenchyma of the phloem?

Answer 52

off loading, storage

Question 53

What are sieve elements

Answer 53

- highly specialized elongated cells - living cells with no nucleus at maturity - primary cell wall - associated with companion cells and albuminous cells (specialized parenchyma cells)

Question 54

What are the two types of sieve elements?

Answer 54

sieve cells | sieve tube members

Question 55

What is the sieve cell?

Answer 55

- in gymnosperms - narrow pores on all walls - allow transport ACROSS CELLS - no sieve plates

Question 56

What is the pair of the sieve cell?

Answer 56

albuminous cell

Question 57

What is the albuminous cell?

Answer 57

- parenchyma cell - associated with the sieve cells - similar function to companion cells - don't share precursor with sieve cell - AID LOADING ON/OFF

Question 58

What is a sieve tube member?

Answer 58

- in angioserms - have narrow pores plus sieve plates - more efficient transport

Question 59

What is the pair of sieve tube members?

Answer 59

companion cells

Question 60

What are companion cells?

Answer 60

- parenchyma cell - associated with sieve tube members - share precursor cell with sieve tube member - aid loading and off loading

Question 61

what happens when cells mature; damaged; what are the pores blocked by?

Answer 61

(P-protein) slime | callose (beta 1-4 glucan)

Question 62

How do aphids retrieve phloem from a tree?

Answer 62

turgor pressure forces sieve tube sap through aphid (honeydew is exuded)

Question 63

true or false; do ants farm aphids so that they can harvest honeydew from them?

Answer 63

true

Question 64

How are aphids examined in the lab

Answer 64

stylet is severed anesthetize aphid harvest phloem in microlitres

Question 65

Why are aphids examined in the lab?

Answer 65

so that signaling molecules in the phloem can be identified (RNA, protein, hormones, viruses)