Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biology > Transport In Plants > Flashcards

Transport In Plants Flashcards

(58 cards)

Start Studying
1
Q

What are the 3 main reasons a plant needs a transport system?

A

1- Metabolic demands
2- Size
3- SA:V ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a dicot plant?

A

Make seeds that contain 2 cotyledons - organs that acts as food stores for the developing embryo and form the first leaves when the seed first germinates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

In the stem of a herbaceous dicot, where are the vascular bundles?

A

Around the edge for strength and support

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a vascular bundle?

A

The xylem and phloem grouped together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

In a herbaceous dicot root, where is the vascular bundle found?

A

In the middle to help the plant withstand the tugging strain from wind

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

In a herbaceous dicot leaf, where are the vascular bundles found?

A

In midrib which also helps to structure the leaf

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a midrib?

A

The main vein in a leaf that carries the vascular bundle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the 2 main functions of the xylem?

A
  • Transport water / mineral ions

- Support

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are xylem vessels?

A
  • The main structures in the xylem

- They are long, hollow structures of dead cells fused end to end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How is lignin relevant to the xylem?

A
  • Lines the walls of xylem vessels in ring, spiral or tube form
  • Contain many bordered pits (unlignified areas) to allow water to leave
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the phloem?

A

Living tissue that transports organic solutes around the plant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

In what direction can organic solutes in the phloem travel?

A

Both up and down the plant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are sieve tube elements?

A

Unlignified hollow structures that are the main transport vessels of the phloem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are sieve plates?

A

Thin pores between sieve tube cells to allow phloem contents out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How are companion cells linked to the sieve tube elements?

A

Via many plasmodesmata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are plasmodesmata?

A

Microscopic channels through cell wall linking the cytoplasm of adjacent cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What do companion cells do?

A
  • Supports sieve tube elements

- Provides ATP (sieve tube cells have no mitochondria)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are root hair cells?

A

Exchange surface in plants where water is taken in from the soil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How are root hair cells adapted to perform their function?

A
  • Microscopic size to easily penetrate the soil
  • Large SA:V ratio
  • Thin surface layer allows for a short diffusion and osmosis pathway
  • High water potential gradient between cell and soil water
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the 2 possible pathways water can take through a root hair cell?

A

Apoplast and symplast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe the symplast pathway

A
  • Water moves across plasma membrane by osmosis

- Moves between cytoplasm of one cell to the next via plasmodesmata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Describe the apoplast pathway

A
  • Water and minerals move through the cell walls
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the endodermis?

A

The layer of cells surrounding the vascular tissue in the roots

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the Casparian Strip?

Study These Flashcards
A

A band of waxy suberin that runs around each of the endodermal cells forming a waterproof layer

25
What is the function of the Casparian Strip?
- Impermeable to water so forces water from apoplast pathway through the cell membrane (symplast pathway) - Membrane repels charged particles
26
Why do xylem cells have a much lower water potential than the endodermal cells?
Solute concentration in endodermal cells is relatively dilute
27
Once inside the vascular bundle, water takes which pathway up the xylem?
Apoplast
28
What helps to give water a push up the xylem?
Root pressure
29
How is root pressure generated?
The pumping of minerals into the xylem producing movement of water by osmosis
30
What is some evidence for the role of active transport in root pressure?
- Adding cyanide to root cells - Active transport requires energy released by ATP and cyanide affects mitochondria, where ATP is held. When cyanide is added to root cells, root pressure stops - Root pressure rises with temperature increases and falls with a fall in temperature - This suggests chemical reactions are involved, i.e the breaking of the phosphates in ATP - If oxygen levels fall, root pressure falls - Oxygen is needed for respiration to release energy
31
Why is water required in a leaf?
A leaf is the site of photosynthesis and water is required for photosynthesis
32
Why is carbon dioxide required in a leaf?
A leaf is the site of photosynthesis and carbon dioxide is required for photosynthesis
33
What is transpiration?
The loss of water vapour from the leaves and stems of plants via stomata
34
What are 3 adaptations of the leaf to aid transpiration?
1- Large SA - captures sunlight to carry out PHS 2- Waxy cuticle - makes leaf waterproof preventing too much water loss by evaporation 3- Stomata - can be opened or closed by guard cells to allow gases to diffuse in or out
35
How does water move in the transpiration stream?
By mass flow
36
What is mass flow?
All water molecules move together as one body, helped by cohesion and tension
37
What is capillary action?
- Water molecules attached to lignin in xylem walls | - Adhesion and cohesion move water upwards
38
What is the benefit of narrow vessel diameter in terms of capillary action?
Prevents the formation of air bubbles
39
Describe the process of transpiration
- Water molecules evaporate from the surface of mesophyll cells into the air spaces in the leaf and then out via stomata to the surrounding air by diffusion - This lowers the water potential of the mesophyll cell, so water moves into this cell by osmosis - This is repeated across the leaf to the xylem - Capillary action occurs in the xylem as water moves up to replace the water lost in the leaf
40
What is the cohesion-tension theory?
- Transpiration of water through stomata - Creates low pressure at top of xylem - Water is pulled up, creating tension - Water molecules stick to each other (cohesion) - Water molecules are sucked up to the leaves (like a straw)
41
What is the evidence to support cohesion-tension theory?
- Changes in the Diameter of Trees - When transpiration is at its highest during the day, xylem tension is at its highest so the diameter shrinks - When transpiration is at its lowest, the tension in the xylem is at its lowest and the tree diameter increases - Breaking a Xylem Vessel - Breaking a xylem vessel causes air to be drawn into the xylem and this stops the continuous flow of water molecules
42
Why may high light intensity be an issue for the transpiration of plants?
- High light intensity means photosynthesis will be occuring at a rapid rate - Therefore a lot of gaseous exchange will be occuring and the stomata will be open frequently - This could mean that the plant loses too much water via the stomata
43
What piece of equipment measures transpiration?
Potometer
44
Why may measuring transpiration not be 100% accurate?
Measuring water loss is difficult so water uptake is measured and we make the assumption that water uptake = water loss
45
Draw and label a potometer
-
46
Why is the stem of the leaf used in a potometer cut at an angle?
To increase its surface area
47
What factors affect transpiration?
- Light - more light increases rate (as it opens stomata) - Temperature - higher temperature increases rate (as increases KE) - Humidity - less humidity increases rate(as increases water vapour gradient) - Wind - more wind increases rate (as increases water vapour gradient)
48
What is translocation?
The process of transporting organic solutes from source to sink (requires energy)
49
In translocation, what are the products of photosynthesis to be transported called?
Assimilates
50
What is the main assimilate transported in translocation?
Sucrose
51
Explain the process of translocation of assimilates from source to sink (Mass flow hypothesis)
Source: - High conc of solutes, e.g. sucrose - Active transport of solute from companion cell into sieve tube element - Decreases water potential - Water moves in by osmosis from companion cell and xylem - Creates high hydrostatic pressure in phloem Sink: - Uses, breaks down or converts the solute into something else - Creates a low concentration of solute (e.g. sucrose into starch) - Increases water potential - Water moves out by osmosis - Decreases pressure in phloem
52
Explain the process of active loading into companion cells
- Active transport of H+ - Out of companion cells - Creates H ion concentration gradient - Facilitated diffusion if H+ back into companion cells - Assimilates (sucrose) move in with H+ - By co-transport
53
What is the evidence to support translocation?
1. Radioactive labelling - Use radioactive C14 label - Grow plants in C14 atmosphere - Measure C14 as it moves down stem 2. Ringing experiments - Remove bark in a ring from the tree trunk (contains phloem but not xylem) - Solutes can’t move up or down - Bulge forms about the ring - Fluid above the ring has more solutes, e.g. sugars than below - Evidence the solutes are moving down
54
What are xerophytes?
Plants that are adapted to living in dry environments
55
What are the adaptations of xerophytes?
- Curled leaves - Stomata sunken in pits - Hairs on epidermis (Water vapour builds up and decreases water vapour gradient) - Thick waxy cuticle (reduces evaporation) - Fewer stomata (less opportunities for the water vapour to come out)
56
What are hydrophytes?
Plants that are adapted to living in/on water | E.g. water lilies
57
What are the adaptations of hydrophytes?
- Air spaces in leaves (leaves float on surface of water so more light for PHS) - Long, flexible leaf stalks (leaves don’t break off in current so don’t need to support any weight) - Stomata on upper surface (allows gas exchange and prevents air spaces filling with water) - Large, thin leaves (increase SA for gas exchange)
58
Name the 7 structures of a leaf in order from top to bottom
``` 1- Waxy cuticle 2- Upper epidermis 3- Palisade cells 4- Spongy mesophyll 5- Lower epidermis 6- Guard cells 7- Stomata ```

Biology (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions