3.1.3: Transport in plants Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Why do plants require a transport system?

A

To ensure all cells receive a strong supply of the nutrients they require.
Especially important as a plant must be able to transport substances up their stem (against gravity).

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

Relate the structure of xylem to its function.

A

● Long, continuous columns made of dead tissue, allowing transportation of water.
● Contain pits, allowing water to move sideways between vessels.
● Thickened with a tough substance, providing structural support

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

Relate the structure of phloem to its function.

A

● Sieve tube elements transport sugars around the plant.
● Companion cells designed for active transport of sugars into tubes.
● Plasmodesmata allow flow of substances between cytoplasm of different cells

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

Describe the structure and function of the vascular

system in the roots.

A

Consists of xylem and phloem. Xylem arranged in an X shape to provide resistance against force. Surrounded by
endodermis, a water supply

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

Describe the structure and function of the vascular

system in the stem

A

Consists of xylem and phloem. Xylem on the inside of the bundle to provide support and flexibility, phloem on the outside. Layer of meristem cells that produce new xylem and phloem tissue when required

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

Describe the structure and function of the vascular

system in the leaves.

A

Consists of xylem and phloem, forms the midrib and veins. Involved in transport and support.

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

Define transpiration.

A

● The evaporation of water from the leaves of a plant.

● Consequence of gaseous exchange; occurs when the plant opens the stomata to exchange oxygen and CO2

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

Name factors that affect the rate of transpiration.

A

● Increased light increases transpiration.
● Increased temperature increases transpiration.
● Increased humidity decreases transpiration.
● Increased air movement increases transpiration.
● Waxy cuticle prevents transpiration.

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

How can we measure transpiration rate?

A

Potometer. Plant cutting is placed in a water-filled tube that contains an air bubble. Rate of transpiration is calculated by measuring the movement of the air bubble over time

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

Define water potential as a mechanism of movement

in plants.

A

● Water potential= the tendency of water to move by osmosis, from high water potential to low.
Pure distilled water has the highest water potential of 0.
● This is the basis by which water moves to the areas it is needed within plants.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Explain what is meant by the apoplastic pathway.

A

A method of osmosis through the root hair cells, where water moves through the cell walls and intercellular spaces.
This pathway can only be used until water reaches the Casparian strip.

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

Explain what is meant by the symplastic pathway.

A

A method of osmosis through the root hair cells, where water moves through the cytoplasm via plasmodesmata. To begin this pathway, water must be actively transported into cells.

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

Explain the cohesion-tension theory.

A

Water molecules form hydrogen bonds with each other, causing them to ‘stick’ together (cohesion). The surface tension of the water also creates this sticking effect. Therefore as water is lost through transpiration, more can be drawn up the stem from the roots

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

Give adaptations of xerophytes that allow them to

live in dry conditions.

A
● Small/rolled leaves
● Densely packed mesophyll
● Thick waxy cuticle
● Stomata often closed
● Hairs to trap moist air
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Give adaptations of hydrophytes that allow them to

live in wet conditions.

A

● Thin or absent waxy cuticle
● Stomata often open
● Wide, flat leaves
● Air spaces for buoyancy

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

Summarise the mechanism of translocation.

A

● Sucrose produced in leaves loaded into sieve tubes via active transport (requiring energy).
● Lowers water potential, causing water to move in from xylem.
● Assimilates move along the sieve tube towards areas of lower hydrostatic pressure (sink). Sucrose diffuses into surrounding cells where it is needed.