Wood Flashcards

1
Q

Softwood

A
  • A type of tissue found in conifers
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2
Q

Hardwood

A
  • Only dicotyledon class of flowering plants
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3
Q

Angiosperm

A
  • Flowering plant
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4
Q

Gymnosperm

A
  • Conifers

- Cone-bearing seed plants

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5
Q

Divisions of trees

A
  • Angiosperms

- Gymnosperms

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6
Q

Classes of Angiosperms

A
  • Dicotyledon (eudicot)

- Monocotyledon

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7
Q

What is wood made from?

A
  • Accumulation of cell walls of the secondary xylem in conifers and dicot flowering plants
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8
Q

What is Xylem and Phloem?

A
  • xylem and phloem are vascular tissue
  • Xylem conducts water upwards
  • Phloem conducts organic constituents
  • Can be secondary or primary
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9
Q

What is secondary growth?

A
  • In diameter of plant (girth)
  • Cambium (lateral meristem)
  • Produce phloem toward outside of plant, xylem toward inside
  • Monocots don’t have secondary growth
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10
Q

What is primary growth?

A
  • Apical

- Produces leaves, non-woody stems, roots

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11
Q

What is the accumulation of xylem tissue?

A

Wood

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12
Q

Annual ring of xylem is what?

A
  • Formed in one growing season
  • Tree rings
  • Dendrochronology to get age of tree by annual accumulation of xylem rings
  • Springwood cells larger than later season cells
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13
Q

Types of xylem cells

A
  • tracheid cells, long and thin with tapered ends

- Vessel elements, short wide cells, align to form pipe-like vessels

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14
Q

What happens when xylem cells form secondary cell walls?

A
  • Cell walls harden with cell death

- Still work in conduction

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15
Q

What type of xylem cells do conifers mostly have?

A
  • Tracheid

- Makes wood more uniform

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16
Q

What type of xylem cells do angiosperms mostly have?

A
  • Dicots have more of both types

- Makes more variety wood

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17
Q

Where does the property of wood come from?

A
  • Lignification of secondary xylem walls

- Thickening of cell wall by lignin gives hardness

18
Q

Lignin

A
  • Polymers of lignin subunits, many variations in final structure
  • Phenolic compounds
  • Up to 40% of plant organic material
  • One of the most abundant organic substances in nature
19
Q

Importance of lignin

A
  • Strengthens around fibrous polysaccharide cell wall
  • Allows plant to become large, tall, upright structures
  • Evolutionarily, adaptation of form in successful transition from aquatic to terrestrial habitat
20
Q

Why are there different types of wood?

A
  • Polymerization of phenolic subunits is ‘random’
  • Final polymers not uniform in result
  • Wood from different sources have different characteristics
21
Q

What makes wood harder?

A
  • More lignification

- Breakdown of random polymerization of subunits is difficult, makes wood durable

22
Q

BC temperate rainforest

A
  • Few species of trees but large numbers of each (softwoods)
23
Q

Tropical rainforest

A
  • Many diverse trees, interspersed (hardwoods)
24
Q

Where is the main source of hardwood in the world?

A
  • Tropical Asia
25
Q

Bark

A
  • Phloem and protective covering layer, periderm

- Periderm expands as plant grows in girth

26
Q

Cork

A
  • Major part of periderm

- Useful for special properties

27
Q

Special properties of Cork and what is Suberin?

A
  • Air-filled principally dead cells
  • cell walls contain suberin,
  • Suberin is a Complex polymer of phenolics and long hydrocarbon chains, A Waxy component
  • Impermeable, buoyant, elasticity
  • No synthetic contains all these properties
28
Q

What do the special properties of cork do for the plant?

A
  • Physical protection, insulation, and fire protection
29
Q

What are uses for cork?

A
  • Wine stoppers
  • Gaskets
  • Badminton shuttlecocks
  • Flooring
  • Acoustic and thermal insulation
  • Bulletin boards
30
Q

History of paper

A
  • Plant fibres into paper first developed by Chinese, documented in year 105 from bark of mulberry tree
  • Didn’t reach Europe for 1000 years
  • Paper rare and valuable in history
31
Q

What is a major product of Canadian forestry?

A
  • Wood pulp paper
32
Q

Wood pulp paper technology developed when?

A
  • late 19th century
33
Q

What kind of wood is suitable for paper?

A
  • Conifer, softwood

- Uniform tracheid cells

34
Q

How is wood pulp paper made?

A
  • Wood stripped of bark and chipped

- Chemical or mechanical process

35
Q

What is the mechanical process for producing paper?

A
  • Simple grinding
  • Slurry washed, screened, and pressed
  • Cheap quality, yellow, and degrades
36
Q

What is the chemical process for producing paper?

A
  • Cook in digester to dissolve lignin
  • Harsh acid or alkali treatments to dissolve other components like resins
  • Bleaching and texturizing agents for white and quality paper
37
Q

What are some of the environmental impacts of paper production?

A
  • Uses energy and strong chemicals
  • 40-50% of worlds industrial logging is for paper
  • Pulp and paper industry responsible for 4% of world energy use
  • Polluter of air and water
38
Q

Has digital documentation and electronic communication resulted in a reduction of paper use?

A
  • No

- But paper going into landfills has been declining since 2000

39
Q

How much of Canada’s waste does paper account for?

A

one third

40
Q

What is the single largest category of paper use?

A
  • Packaging accounts for 41% of all paper used