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Biology > Topic 4 Wood > Flashcards

Topic 4 Wood Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Plant cell ultrastructure

A
  • cell wall
  • cell membrane
  • cytoplasm
  • nucleus
  • nucleolus
  • ribosomes
  • chloroplasts
  • vacuole (tonoplast)
  • amyloplasts
  • rER
  • sER
  • Golgi apparatus
  • mitochondria
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2
Q

Cell wall

A
  • made of cellulose
  • provide strength and support to regular shape
  • there are pores within the walls called plasmodesmata which connect two cells together by their cytoplasm enabling exchange and transport of substances
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3
Q

Vacuole

A
  • fluid filled space in the cytoplasm
  • surrounded by a single membrane (tonoplast)
  • permanent in plant cells
  • contains water, ions, sugars (cell sap)
  • can also be used for storage
  • keeps cells turgid
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4
Q

Amyloplasts

A
  • organelles that store amylopectin
  • has a double membrane
  • amylopectin sometimes shown as concentric rings
  • amylopectin can be broken down into alpha glucose and used to provide energy (is an energy store) for the plant cell
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5
Q

Chloroplasts

A
  • found in photosynthetic cells
  • site of photosynthesis (thylakoid membranes)
  • have a double membrane and many internal membranes
  • fluid filled interior called the stroma
  • contain their own DNA (typically circular)
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6
Q

Chloroplast structure

A

the thylakoid space has thylakoid membranes and stacks of these are called grana (granuum) in a fluid called the stroma

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7
Q

Plant cells build columns and tubes from specialised cells which are stiffened…

A

by another polymer called lignin

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8
Q

What is cellulose?

A

is a polymer of β glucose which forms during a condensation reaction creating glycosidic links

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9
Q

How are cell walls made strong but flexible?

A

the cellulose microfibrils are laid down at different angles

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10
Q

Within a cell wall there are…

A

cellulose microfibrils

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11
Q

What is the glue holding the microfibrils made up of?

A

pectins and hemicelluloses

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12
Q

Summary of cellulose

A
  • polymer of β glucose
  • unbranched, straight chains
  • alternating molecules are flipped 180° allowing it to make a polymer chain
  • 1,4 glycosidic bonds formed through a condensation reaction
  • hydrogen bonds join cellulose chains together making bundles of fibres called microfibrils
  • microfibrils are laid at angles for strength
  • high tensile strength
  • permeable to water and gases
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13
Q

Plasmodesmata

A

cytoplasmic links between adjacent plant cells (holes in cell walls; both the primary and secondary aren’t there)

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14
Q

Vascular bundle

A

xylem, phloem, schlerenchyma

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15
Q

How do phloem sieve tubes form?

A
  • cells elongate and lose cytoplasm, nucleus and most other organelles
  • the ends don’t break down completely but form sieve plates between cells
  • next to each phloem cell is a companion cell which keeps the phloem cell alive
  • it is metabolically active and is used in moving photosynthesis products up and down the plant
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16
Q

What is transported in translocation?

A
  • sucrose
  • hormones
  • amino acids
  • minerals
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17
Q

Phloem transports… (where to where)

A

substances made in the leaves to other parts of the plant

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18
Q

Lignification

A
  • deposit lignin into cell walls - makes it woody

- restricts entry of water and solutes into cell so they die

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19
Q

Schlerenchyma

A
  • long elongated hollow cells
  • dead cells
  • closed ends so not involved in water transportation
  • lignin in walls for strength
  • thick walls relative to lumen size
  • bundles or cylinders
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20
Q

Why do phloem sieve tubes need to be metabolically active?

A

for active transport

21
Q

What is translocation?

A

the movement of nutrients around a plant (can refer to minerals dissolved in water which are transported in the xylem but generally refers to sugars, amino acids and other organic molecules)

22
Q

Features of translocation

A
  • it is bi-directional (goes both directions)
  • it is an active process requiring energy
  • goes from source –> sink
23
Q

What is transported in the phloem and how?

A

amino acids, sucrose, hormones, minerals all by translocation

24
Q

Another name for flowering plants

A

angiosperms

25
Q

Angiosperms: monocotyledons

A
  • embryos have one seed leaf
  • leaves have parallel veins
  • rarely grow large
  • flowers in multiples of 3
26
Q

Angiosperms: dicotyledons

A
  • embryos have two seed leaves
  • leaves have a network of veins
  • can grow large by producing wood (lignin)
  • flowers in multiples of 4/5
27
Q

Transpiration

A

the loss of water from plant leaves (through the stomata)

28
Q

Features of water

A
  • is dipolar (oxygen negative, hydrogen positive)
  • hydrogen bonds occur between two water molecules (more of these makes it stable)
  • is an effective solvent
  • has a large specific heat capacity
29
Q

Xylem

A

are dead, hollow, lignified and have pits which allow movement of water and ions between the xylem and phloem

30
Q

Cohesion (water)

A

water molecules ‘stick’ together which holds up the column of water; positive and negative ends cohere so as some molecules leave the plant others are pulled up behind them

31
Q

Adhesion (water)

A

water molecules ‘adhering’ to something else; in the xylem water adheres to the walls which helps the water move upwards resisting gravity

32
Q

How would you investigate transpiration

A

-using a potometer
-cut stem underwater
-seal in potometer keeping underwater so no air bubbles
-bubble moves representing volume lost
affecting it air movement doesn’t, humidity doesn’t, light increases

33
Q

Xerophytes

A

plants that have evolved to reduce transpiration rates

34
Q

Reducing water loss adaptations

A
  • waxy cuticle
  • stomata on underside of leaves –> no direct sunlight
  • stomata close at night
  • deciduous plants lose leaves in winter
35
Q

Water flow is…

A

unidirectional (if one part is damaged the whole chain falls)

36
Q

Mass flow in plants

A

water moving through the xylem is mass flow for inorganic ions - movement down a concentration gradient (are taking in at roots and needed elsewhere)

37
Q

Plants primary cell wall

A
  • cellulose microfibrils are all oriented in a similar direction which means it can elongate and allows further growth
  • is fully permeable with no lignin
38
Q

Plants secondary cell wall

A
  • cellulose microfibrils are laid down at different angles

- lignin may be laid down as will (lignin is impermeable to water)

39
Q

Middle lamella

A

region between cell walls of adjacent plant cells which is made of calcium pectates –> glues cells together

40
Q

Human uses of xylem and schlerenchyma

A

support –> fibres e.g. fabric and ropes

41
Q

Human uses of chemical defences

A

antibacterial –> medicines, cosmetics, pesticides

42
Q

Human uses of seeds

A

food starch based products

43
Q

Mineral ions

A

are actively transported into root cells - this needs ATP as its going against the concentration gradient

44
Q

Lack of mineral ions =

A

deficiency symptoms

45
Q

Magnesium ions

A
  • part of the chlorophyll molecule which is used in photosynthesis (absorbs sunlight, activates enzymes)
  • if lacking yellow leaves will be seen
46
Q

Nitrate ions

A
  • used in amino acids which make proteins and allows plant growth
  • if lacking yellow leaves and stunted growth
47
Q

Calcium ions

A
  • used in respiration and for growth also is in pectate in cell walls so cells won’t be able to stick together and will affect membrane permeability
  • if lacking plant will have stunted growth
48
Q

Pits

A

secondary cell wall is absent

Biology (14 decks)

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