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functions midterm > chapter 36: resources acquisition and transport in vascular plants > Flashcards

chapter 36: resources acquisition and transport in vascular plants Flashcards

1
Q

What does the xylem transport and where?

A

Transports water and minerals from roots to shoots

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2
Q

What does the phloem transport and where?

A

Transports photosynthetic products from sources to sink

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3
Q

What is the function of the stem?

A

Conduits for water and nutrients and as support structures for leaves.

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4
Q

What is light capture affected by?

A

By the shoot length and the branching pattern.

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5
Q

There is a trade off with the shoot and what does it affect?

A

Shoot length and its branching pattern.

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6
Q

What is phyllotaxy?

A

Arrangement of leaves on stem.

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7
Q

What is important about phyllotaxy?

A
  1. It is specific to its species
  2. important to light capture
  3. angiosperm have alternate phyllotaxy
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8
Q

What is the leaf area index?

A

It is the ratio of total upper leaf surface of a plant divided by surface area of land.

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9
Q

What is affected by leaf orientation?

A

The light absorption (horizontal leaves capture more light)

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10
Q

What is the importance of the root architecture?

A
  1. Soil is a resource mined by roots
  2. Root growth will adjust to local conditions
  3. Roots are less competitive with it’s own species rather than other species.
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11
Q

What are the two major pathways through plants?

A
  1. Apoplast: consists of everything external to plasma membrane (cell walls, extracellular spaces and interior of vessels)
  2. Symplast: consists of cytosol of living cells in a plant + plasmodesmata.
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12
Q

What are the three transport routes for water and solutes in plants?

A
  1. Apoplastic route: through cell walls and extracellular spaces
  2. Symplastic route: through cytosol
  3. Transmembrane route: across cell walls
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13
Q

Why is short-distance movement important?

A

Controls plasma membrane permeability

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14
Q

What are some short-distance transport examples?

A
  1. proton pumps: pumping H+ establishes pH gradient and membrane potential
  2. H+/sucrose cotransporter: energy of H+ gradient cotransports solutes
  3. H+/NO3- cotransporter: energy of H+ gradient cotransports ions
  4. Ion channels: alllow only certain ions to pass
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15
Q

What is osmosis?

A

Diffusion of water into or out of a cell affected by solute concentration.

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16
Q

What are the 3 possible reactions during osmosis?

A
  1. Isotonic: same amount of solute concentration inside vacuole and in environment - Flaccid Cell
  2. Hypotonic: solution has lower solute concentration, cell gains water - Turgid Cell
  3. Hypertonic: amount of solute is higher in environment, cell undergoes plasmolysis - Plasmolyzed Cell
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17
Q

What does tugor loss in plant cause?

A

wilting

18
Q

What happens when a cell undergoes plasmolysis?

A

Protoplast shrinks and pulls away from cell.

19
Q

What are aquaporins?

A

They are transport proteins in cell membrane that facilitate passage of water.

20
Q

What does effective long distance transport require?

A

bulk flow: movement of a fluid driven by pressure.

21
Q

Where do water and solutes move in xylem?

A

They move through the tracheids.

22
Q

Where do water and solutes move in phloem?

A

They move through the sieve-tube.

23
Q

Where does most water and mineral absorption occur?

A

Near the root tips, where root hairs are located and the epidermis is permeable to water.

24
Q

What does active transport cause?

A

Causes greater concentration of essential minerals in roots than soil.

25
Q

What is the endodermis?

A

Innermost layer of cells in the root cortex, surrounding vascular cylinder.

26
Q

What is the Casparian strip?

A

It blocks apoplastic transfer of minerals from the cortex to vascular cylinders.

27
Q

What is xylem sap?

A

It is water and dissolved minerals transported from roots to leaves by bulk flow.
This involves transpiration, as transpired water is replaced as water travels up from roots.

28
Q

What is transpiration?

A

It is evaporation of water from plants surface. It drives bulk flow, and does not require energy from plant

29
Q

What is the cohesion-tension hypothesis?

A

It is that transpiration and water cohesion pull water from roots to shoots. (xylem sap is normally under negative pressure or tension)

30
Q

What is the use of the stomata?

A

It is responsible for water vapour in airspaces to exit leaf.

31
Q

What is the role of adhesion in xylem cells?

A

Water molecules are attracted to cellulose in the xylem cell walls through adhesion. This helps offset force of gravity.

32
Q

What is the cohesion-tension mechanism?

A

Maintaining movement of xylem sap against gravity.

33
Q

What are the differences between bulk flow and diffusion?

A
  1. driven by differences in pressure potential not solute potential
  2. occurs in hollow dead cells not across membranes of living cells
  3. moves entire solution not just water or solutes
  4. much faster
34
Q

What is higher in leaves, area or volume and why?

A

They have larger surface ares and high surface-to-volume ratios. This increases photosynthesis and increases water loss through stomata.

35
Q

What are the changes in turgor pressure that determine if stomata is closed or open?

A

When the cell is turgid, the guard cells will bow outward and the pore between them will open

When the cell is flaccid, the guard cells become less bowed and the pore closes.

36
Q

What triggers the opening of the stomata?

A
  1. Light
  2. CO2 depletion
  3. Internal “clock” in guard cells
37
Q

What triggers the closing of the stomata?

A
  1. Drought
  2. High Temperatures
  3. Wind
38
Q

What is the internal 24h cycle

A

circadian rhythms

39
Q

What are xerophytes?

A

plants adapted to arid climates

40
Q

What is translocation?

A

Process where products of photosynthesis are transported through phloem.

41
Q

What is pressure flow?

A

It is positive pressure that drives bulk flow to move phloem sap through a sieve tube.

functions midterm (12 decks)

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