Lecture 4- Plant Structure; Cell Types and Primary Growth Flashcards

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1
Q

There are two systems in vascular plants

A

Shoot system: above ground, consists of shoot with nodes, depends on water and minerals
Root system: below ground, depends on photosynthates

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2
Q

Root

A

an organ that anchors a vascular plant in the soil
absorbs minerals and water
stores carbohydrates

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3
Q

Primary root

A

The first root (and organ) to emerge from a germinating seed
Originates in the embryo
Branches to form lateral roots

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4
Q

Lateral root

A

Greatly enhances the ability of the root system to anchor the plant and acquire water and minerals from soil

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5
Q

Taproot

A

One main vertical root
Develops from the primary root
Prevents the plant from toppling
Allows plant to be tall

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6
Q

Stem

A

An organ that raises and separates leaves, exposing them to sunlight
Raise reproductive structures, facilitates the dispersal of pollen and fruit
Consists of nodes: points at which leaves are attached
internodes: the stem segments between nodes

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7
Q

Axillary bud

A

Structure that can form a lateral shoot, called a branch

Young ones grow very slowly

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8
Q

Apical bud

A

Also called terminal bud
Composed of developing leaves, nodes, and internodes
The shoot tip, where most of the growth of a young shoot is

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9
Q

Leaf

A

The main photosynthetic organ

Consist of a blade and a petiole

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10
Q

Blade

A

Hard, flat part of leaf

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11
Q

Petiole

A

The stalk that joins the leaf to the stem at a node, the soft part

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12
Q

Cell Walls

A

Extracellular- outside the membrane and is made by the membrane
Composed mostly of cellulose: polysaccharide of glucose units
Made of cellulose microfibrils: adjacent, parallel cellulose molecules

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13
Q

There are two kinds of cell walls in land plants:

A

primary and secondary

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14
Q

primary cell wall

A

Primary wall
Thin
In all plant cells
Made first

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15
Q

secondary cell wall

A
Secondary wall
Thicker than primary wall, made for strength
In some plant cells 
Made on the inside 
Made seconds
Provides support and protection
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16
Q

Functions of the Plant Cell Wall

A

Determines and maintains cell shape

Provides support and mechanical strength
allows plants to get tall, hold out thin leaves to obtain light

3) Prevents the cell membrane from bursting
resists water pressure

4) Controls the rate and direction of cell growth and regulates cell volume
5) Ultimately responsible for the plant architectural design
6) Physical barrier to a) pathogens and b) water in suberized (waxy) cells. However, remember that the wall is very porous and allows the free passage of small molecules

7) Carbohydrate storage
the components of the wall can be reused in other metabolic processes (especially in seeds)

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17
Q

The cell wall is composed of 3 polysaccharides:

A

cellulose, hemicellulose, pectin

18
Q

cellulose

A

Polymer (chain) of up to 25,000 glucose molecules
approx 36 chains bond to make microfibril
made up of cellulose microfibrils

19
Q

hemicellulose

A

Cross-linking glycans bond with cellulose

20
Q

pectin

A

Jellylike, acts as the glue

Holds everything together

21
Q

why do cells stick together

A

middle lamella: pectic substances

22
Q

types of plant cells

A
6:
Schlerenchyma
Parenchyma
Epidermal
Collenchyma
Trachieds and vessel elements
Sieve elements
23
Q

Schlerenchyma

A
-thick secondary wall: strong and woody 
two types: fibres that unite into strands, schlerieds that don't unite
-dead and hard
function: support, strength 
-ex: rope, clothing
24
Q

Parenchyma

A

-Simple cells that have generalized functions
Least specialized
Usually lack secondary wall
Can often divide and differentiate at maturity
most abundant, can perform all kinds of functions based on their location
Function:
General
Most metabolic processes (photosynthesis, storage, secretion)

ex: fruit flesh, pith, and cortex of stems and roots

25
Q

Epidermal

A
Epidermal
Outermost cells of all land plants
Single layer 
Function:
Waterproofing: keeps water out and in
Protection from bacteria, fungi, viruses
Can be highly specialized: make hairs (trichomes) , nectar, guard cells- gas exchange 
Cuticle
Formed by the epidermal cells
Outermost part is wax
Waxy coating on the epidermal surface, helps prevent water loss, pathogens, and UV radiation
26
Q

Collenchyma

A
Thick, uneven primary wall
No secondary wall
Often occur in strands 
Alive at maturity: can elongate 
Function:
Support, especially of young and growing organs 

ex: celery leaf and midrib and petiole

27
Q

Tracheids and vessel elements

A

Water conducting cells of the xylem
Dead at maturity (when they are functioning, they are dead)
Secondary wall lignified: woodlike polymer, often spiral
Two kinds: tracheids and vessel elements
Function:
Support
Supply of water and minerals

Xylem tissue: tracheids and vessel elements
Differ in their shape

Tracheids
In the xylem of all vascular land plants
Tapered, goes through pit

Vessel Elements
Wider, shorter, not tapered
Thick, stacked on top of each other

28
Q

Sieve elements

A

Sieve elements
Sugar conducting cells of the phloem
Alive at maturity
With companion cell: connected to the sieve-tube by plasmodesmata
Function:
Transport sugars (especially sucrose) in liquid form, other organic compounds, some minerals

29
Q

Meristem

A

Ultimate source of all parts of mature sporophyte
Undifferentiated
Can divide forever

30
Q

Two types of meristems

A

Apical and Lateral

31
Q

Apical Meristems

A
  • Shoot and Root AM
  • Make 3 meristems, those meristems go off to make 3 primary tissues
  • primary growth: growth in height
  • located at tips of roots and shoots
32
Q

Describe primary growth

A

1) Apical meristem produces 3 new meristems: Protoderm that goes on to produce dermal tissue/epidermis. Pro cambium goes on to produce vascular tissue/ xylem to inside, phloem to outside. Ground meristem produces ground tissue: pith and cortex, lies in-between protoderm and pro cambium
Allows plant to grow vertically

33
Q

Draw a shoot apical meristem

A

youngest tissues at top

oldest are at the bottom

34
Q

Shoot structure of Monocot and Eudicot

A

fff

35
Q

Root apical meristem drawing

A

k

36
Q

root cap is produced by the

A

protoderm

  • protects root as it drives down into the soil
  • dead cells
37
Q

Stele

A
  • protects all vascular tissue in the root

- all vascular tissue

38
Q

Primary growth in roots

A

1) Zone of Cell division. Root AM keeps dividing in cells.
2) Zone of Elongation. Root cells get longer and grow
3) Zone of Maturation/Differentiation: cell growth stops, root hairs grow

39
Q

Root structure in Monocot and Eudicot

A

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40
Q

Endodermis

A

innermost layer of cortex
one cell thick barrier between cortex and vascular tissue
-casparian strip: permits passage

41
Q

Stele

A

all vascular tissue in root and stem
everything inside endodermis
pericycle