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BIOLOGY REVISION > Transport in plants 3.3 > Flashcards

Transport in plants 3.3 Flashcards

1
Q

What 4 things do plants need to get?

A

Plants need:

  • o2
  • h2o
  • sugars
  • minerals
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2
Q

What does it mean if a plant is dicotyledonous?

A

Dicotyledonous plants have 2 seeded leaves

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3
Q

Briefly how is vascular tissue distributed in dicotyledonous plant?

A

Xylem and phloem are found in bundles and they also have sclerenchyma and collenchyma for strength and support

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4
Q

What does xylem transport and which direction is thus?

A

Xylem transport water with dissolved minerals UP theplant

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5
Q

What does the phloem transport and what direction?

A

Phloem transport assimilates UP and Down the plant

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6
Q

How are xylem and phloem arranged in a YOUNG ROOT?

A

xylem is arranged in a cross in the middle and phloem is between the cross’s legs

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7
Q 
Where is the 
-endodermis
-pericycle
-coirtex
-medulla
in a YOUNG ROOT
A

Young root:

  • endodermis is the ring around the xylem etc
  • pericycle is on the inside of the endodermis
  • cortex is the layer outside of the endodermis
  • medulla is all that in the cortex
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8
Q

How is xylem and phloem arranged in the STEM?

A

Stem;

  • xylem is the inner most blob
  • phloem is the blob after the xylem
  • xylem and phloem are separated by cambium
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9
Q

Where is Sclerenchyma and collenchyma in the stem?

A

Sclerenchyma is the outermost blob

Collenchyma is in the inside of ring

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10
Q

Compare distribution of vascular tissue in woody and non woody plants stems

A

In woody plants the xylem and phloem remain in the discrete bundles but in non woody plants eventually these bundles become a ring

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11
Q

Where are xylem and phloem in the LEAF?

A

In the leaf the xylem are above the phloem

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12
Q

What is the section in the leaf that contains the xylem and phloem~?

A

The xylem and phloem are in the central midrib

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13
Q

What arethe 3 things the xylem contains?

A

The xyelm:

  • H20 and dsissolved minerals
  • fibres to supoort the plant
  • parenchyma to spearateand support xylem
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14
Q

What are bordered pits and how do they help xyelms function?

A

Bordered pits areareas of imcomplete lignification and they allow water to move from one zyem vessel to another

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15
Q

What happens to the end walls of cells and why does this help the xylem functions?

A

In xylem the end walls and cell contents decay, leaving narrow and hollow tubes. This means water can travel in a continuous column of water and the narrowness means water does not break

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16
Q

What does lignin do and how does this help the function of xylem?

A

Lignin impregnates cell walls to kill them, waterproof them and add strength. This means the vessels do not cave in

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17
Q

What are the three ways lignin can be deposited?

A

Lignin can be deposited in different patterns:

  • Spiral
  • Annular (rings)
  • reticulate (broken rings)
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18
Q

How does different lignin patterns help the function of the xylem?

A

Different patterns of xylem prevent the cells getting to rigid so they can still be flexible

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19
Q

Why does xylem have no cross walls and no cell contents?

A

Xylem have no cell walls or cell contents so that the movement of water is not impeded

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20
Q

What is sap?

A

Sap is sucrose that is dissolved in water and this is what the phloem transports

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21
Q

What are the three components of phloem?

A

Components of phloem:

  • companion cells
  • Sieve tubes
  • sieve plates which are perforated
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22
Q

What are companion cells?

A

Companion cells have a large nucleus, dense cytoplasm, lots of mitochondria. They to keep sieve tube elements alive and help do active loading (they have many mitochondria)

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23
Q

What an adaptation of sieve tubes and sieve plates?

A

Sieve tubes have little cytoplasm and no nuclei allowing for the mass floe of sap
Sieve plates perforations allow for movement between one element and the next

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24
Q

What is osmosis?

A

Osmosis is the movement of eater from an area of high water potential to low water potential

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25
Q

What is the water potential of pure water?

A

Pure water has the highest water potential- 0

26
Q

What happens when a plant cell takes in water?

A

When a plant cell takes in water it becomes turgid as the cell wall supports it

27
Q

What happens when a plant cell loses water?

A

When a plant cell loses what the cell membrane breaks away from the cell wall- plasmolysis and the cell becomes flaccid

28
Q

What are plasmodesmata?

A

Plasmodesmata are cytoplasmic bridges connecting 2 cells

29
Q

What are the three water pathways?

A

Wzter pathways:

  • Apoplast between cells
  • Symplast between the cells cytoplasms
  • Vacuolar between cytoplasms and vacuoles
30
Q

What is transpiration?

A

Transpiration is the loss of water vapour through aerial parts o the plant through the stomata

31
Q

Describe the process of transpiration

A

Transpiration:
1. water moves by osmosis from the xylem into a spongy mesophyll cell
2. water evaporates from the spongy mesophyll cell into the space which lowers the spongy mesophyll cells water vapour potential gradient.
3. this creates a water vapour potential gradient meaning even more water can evaporate
4. evaporates out of the stomata
4.

32
Q

What are the areas in the root involved in the transpiration stream?

A

root—-cortex—-casparian strip— medulla—xylem

33
Q

Where is the root hair cell in the plant?

A

The root hair cell is in the epidermis

34
Q

Where is the casparian strip?

A

The casparian strip is in the endodermis

35
Q

What is the role of the casparian strip?

A

The role of the casparian strip is to stop the apoplast pathway, forcing all the water into the symplast pathway

36
Q

Describe the process of water uptake and movement across the root

A
  1. active loading of mineral ions from the soil into the root hair cell lowering its water potential
  2. water enters by osmosis
  3. ions move into the medulla of the root lowering the water potential of the medulla
  4. water moves by osmosis into the medulla
  5. the xylem is in the medulla so also gets the water
37
Q

How does water move up the stem?

A

Water moves up the stem through the xylem by mass flow helped by; root pressure, transpiration pull and capillary action

38
Q

What is root pressure?

A

Root pressure helps mass flow. Pressure in the root medulla builds up and so forces water into the xylem and therefore up the xylem. (only pushes water a bit not very far)

39
Q

Explain transpiration pull and what property of water it relies on

A

Transpiration pull relies on water’s cohesion (attracted to each other). Loss of water by evaporation needs to be replaced by water coming up the xylem, so as ,molecules evaporate the column of water of gets pulled up as one chain

40
Q

What is capillary action and what property of water does it rely on?

A

Capillary action is reliant on adhesion of water so water can be pulled up the sides of xylem vessels

41
Q

What is the transpiration pull called?

A

Transpiration pull is called the cohesion tension theory

42
Q

Why would just one air bubble, blocking the vessel, not stop the flow of water?

A

One air bubble does not kill the plant as the bordered pits in xylem mean it can enter another vessel, moving around the air bubble

43
Q

Briefly over view the whole transpiration stream

A

Transpiration stream:

  1. minerals actively transported into roots and xylem
  2. cohesion lets water to move by mass flow pulled by tension above
  3. movement of water out of the xylem crates tension + low hydrostatic pressure
  4. osmosis moves water across the leaf
  5. diffusion of water vapour out of stomata
44
Q

What is translocation?

A

Translocation is the movement of assimilates through the plant

45
Q

What are assimilates?

A

Assimilates are substances made by the plant using substances from the environments

46
Q

What are sources? Pressure?

A

Sources make sucrose and load it onto the phloem. There is a high hydrostatic pressure here. e.g. leaves and roots

47
Q

What are sinks? Pressure?

A

Sinks are where sucrose gets used and takes sucrose out of the phloem. They have a low hydrostatic pressure. e.g. growing parts or roots

48
Q

How is the hydrostatic pressure gradient produced and what does it mean?

A

The hydrostatic pressure gradient is made by removal of assimilates at sinks. This causes mass flow in the phloem

49
Q

In terrestrial plants what is the trade off?

A

In terrestrial plants adaptations have to be a trade off between gases and water. The stomata need to be open for gases but this loses water

50
Q

What are the aim of terrestrial plants adaptations?

A

Terrestrial plants wish to reduce water loss and replace any that is lost

51
Q

What are 3 adaptations of terrestrial plants?

A

Adaptations of terrestrial plants:

  • thick waxy cuticle to stop water evaporating from the epidermis
  • stomata are on the underside of the plant to stop exposure to sun and heat (heat causes evaporation)
  • stomata close at night
  • deciduous plants leaves fall in winter as there are no need for stomata
52
Q

What are xerophytes?

A

Xerophytes are plants which live in extremely dry conditions

53
Q

What are hydrophytes?

A

Hydrophytes are plants that live in very wet conditions

54
Q

What are some adaptation of marram grass?

A

Adaptations of marram grass (Xerophyte):

  • thick waxy cuticle
  • stomata in sunken pits under the leaf to reduce air movement to reduce evaporation
  • rolled leaves to trap water vapour increasing humidity so less evaporation
  • dense spongy mesophyll so less area for evaporation
55
Q

What are some adaptations of cacti?

A

Cacti adaptations (xerophyte)

  • thick waxy cuticle
  • spines instead of leaves reduce surface area
  • green stem for photosynthesis as no leaves
  • widespread roots to take advantage of rain
  • ribbed/fluted stems
56
Q

What are some general adaptations of Xerophytes?

A

Adaptations of xerophytes:

  • stomata close when plant detects there is little water
  • increase salt contents of cells to reduce water potential leading to less steep water potential gradients so less evaporation
  • tap roots (long) reach deep underground water
57
Q

What does increasing salt contents of cells do?

A

Increasing salt contents of cells reduces water potential leading to less steep water potential gradients so less evaporation

58
Q

What is the issue hydrophytes face?

A

Hydrophytes need to stay afloat and need to get oxygen to their submerged tissues

59
Q

What are the adaptions of hydrophytes?

A

Adaptation of hydrophytes:

  • large air spaces in the leaf
  • stomata are on upper epidermis so they are exposed to gases
  • large air spaces in the stem for quick oxygen diffusion and to keep them afloat
60
Q

How do hydrophytes do transpiration?

A

Hydrophytes transpire by having hydathodes at the tips of their leaves that release water droplets. These can evaporate from the leafs surface

BIOLOGY REVISION (21 decks)

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