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B - Transport > Plant's > Flashcards

Plant's Flashcards

1
Q

What do plants transport in the xylem and phloem?

A

Xylem - Water and soluble materials

Phloem- Sugars (Surcose)

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2
Q

What is the structure of the Root?

A

Xylem- X shaped region
Pholem - Circles in each part
Endodermis around the bundles and inside the endodermis there are meristem cells
This arrangement allows for strength in the stem

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3
Q

What is the function of the parenchyma cells?

A

They function in storage, photosynthesis, and as the bulk of ground and vascular tissues.

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4
Q

What is the function of Sclerenchyma?

A

They are strong, thick cells that provide most of the support in a plant. They are known to have extremely thick cell walls

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5
Q

What is the structure of the stem?

A

Vascular bundles around the perimeter of the stem to provide strength and flexibility. The phloem is found towards the inside of the bundle. The xylem is found towards the outside. Cambium is the meristem cells.

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6
Q

What is the structure of the xylem?

A
  • Thick cell walls with lignin
  • Lignin water proofs the cell
  • End walls decay leaving a long hallow tube
  • You have pits where the lignification is not complete
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7
Q

What are the adaptation of the xylem?

A
  • Made from dead cells end to end to form a continuous column
  • The tubes are narrow so the column does not break easily and capillary action is effective
  • Pits allow cross tansport to another xylem vessel
  • Liginin deposited in spirals so it allows the plant to grow and the stem/branch to bend
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8
Q

Why is the flow of water not impeded?

A
  • There are no cell walls
  • There are no cell contents
  • There is no nucleus or cytoplasm
  • Lignin thinking prevent the walls from collapsing
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9
Q

What is the structure of the Phloem?

A

It is bi directional it contains two types of cells the sieve tubes and the companion cells

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10
Q

What is the function and structure of sieve tubes?

A
  • Sieve tubes contain little or no cytoplasm and no nucleus

- Sieve plates allow sap to flow between the tubes

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11
Q

What is the function and structure of companion cells?

A

-Have a large nucleus and dense cytoplasm
-Lots of mitochondria to produce ATP needed for active transport
-They carry out the metabolic processes needed by sieve tubes
-Which include loading sucrose
They are linked to the tubes with plasmodesmata these allow the flow of minerals and communciation

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12
Q

Why is the water potential in the cytoplasm usually low?

A

It contains salts and sugars because they are fewver free molecules available than pure water.

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13
Q

What happens when you place a plant cell in pure water?

A
  • It will take up water

- It will then become turgid as the inside of the cell exerts a pressure on the walls

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14
Q

What happens if you place a plant cell in a low water potential solution?

A

-It will lose water
Evnetually the cytoplasm does not push against the wall and the cell will be become plasmolysed
-Plasma membrane loses contact with the wall

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15
Q

What are the ways water moves between plant cells?

A
  • Apoplast pathway
  • Symplast pathway
  • Vacuolar Pathway
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16
Q

How does the apoplast pathway work?

A

Water moves through the space between the cell walls the water does not pass through any plasma memebrane so dissolved slats and ions can be carried with water

17
Q

How does the symplast pathway work?

A

Water enter the cell cytoplasm through the membrane it then passes trhough the plasmodesmata. So the cytoplasma of the cells are linked

18
Q

How does a vacuolar pathway work?

A

similar to the symplast however water can also pass between the vacuoles.

19
Q

How is water taken up from the soil?

A
  • Roots contains root hair cells that increase SA
  • Absorb minerals bt active transport to reduce water potential of cytoplasm
  • Which means water can move by osmosis down a concentration gradient
20
Q

How does water move across the root?

A
  • Driven by an active process in the endodermis
  • Water is transported using the various pathways
  • It contains the Casparian strip which blocks off the apoplast pathway
  • Endodermis move minerals by AT from cortex into xylem which decreases the water potential of the xylem
  • Which creates a gradient
21
Q

What is the role of the Casparian strip?

A

-Blocks the apoplast pathway
-Ensure that water and dissolved nitrate ions have to pass into cytoplasm
-There are transporter protein in membranes
-Which means nitrates can be transported from the cytoplasm of cortex to xylem
To lower water potential

22
Q

What are the 3 ways water moves up the stem?

A
  • Root pressure
  • Transpiration Pull
  • Capillary action
23
Q

What is root pressure?

A

The action of endodermis moving minerals into xylem to drive water into xylem. This forces water up the xylem and pushes water up.

24
Q

What is Tension?

A

Tension causes the xylem to bend inwards

25
Q

What is Cohesion?

A

The force resulting from the attraction between molecules of the same substances. Molecules of water stick together because of the hydrogen bonds

26
Q

What is transpiration pull?

A

The loss of water by evaporation from the leaves must be replaced by water coming up from the xylem. Cohesion forces mean molecules are held together in a long chain. As molecules are lost at the top of column the whole column is pulled up crating a transpiration stream.

27
Q

What is capillary action?

A

Hydrogen bonds attract water molecules to the sides of the xylem vessels which is known as adhesion. The forces of attraction can pull the water up the sides of the cell vessel

28
Q

What is transpiration?

A

Loss of water vapor through the leaves.

  • Osmosis from the xylem to mesophyll cells
  • Evaporation from the surface of mesophyll to inter cellular spaces
  • Diffusion of water vapor from inter cellular places out of the stomata
29
Q

Why is water needed?

A
  • In leaves for photosynthesis
  • let cells grow and elongate
  • keeps cells turgid
  • carry useful minerals up the plant
  • evaporation of water to keep plant cool
30
Q

What are the factors that effect transpiration?

A
  • Number of leaves
  • Number,size and position of stomata
  • Presence of cuticle
  • Light
  • Temperature
  • Relative Humidity
  • Air movement
  • Water availability
31
Q

What are hydrophytes?

A

They are plants that live in water

32
Q

What are the adaptations of a hydrophyte?

A
  • Thin or no waxy cuticle because lots of water so evaporation is not an issue
  • Open stomata on the upper surfaces maximizing the number of gaseous exchange, usually open all time
  • No need for supporting structures
  • Wide flat leaves to capture alot of light
  • Small roots because water goes directly into stem
  • Large SA this makes a larger area for photosynthesis
  • Air sacs enable leaves to float on water
33
Q

What is an Xerophyte?

A

A plant that lives in a dry environment

34
Q

What are the adaptations of an Xerophyte?

A

-Think waxy cuticle to limit evaporation
Sunken stomata to reduce air movement and produce a microclimnate of still air
-Reduced stomata

B - Transport (1 decks)

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