Key Area 5 - Plant Transport Systems

Question 1

What are a plants main organs?

Answer 1

Plants have 3 main organs:
- Roots
- Stems
- Leaves

Question 2

What is the function of the root?

Answer 2

• Anchors the plant in the soil
• Absorbs water and minerals
• Stores food

Question 3

What is the function of the stem?

Answer 3

• Contains xylem and phloem
• Connects leaves
• Supports plant

Question 4

What is the function of the leaves?

Answer 4

The main site of photosynthesis in a plant.

Question 5

What is the structure of a leaf?

Answer 5

Waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis, stoma, vein, guard cell.

Question 6

What is the function of the waxy cuticle?

Answer 6

Waxy outer waterproof covering that reduces water loss by evaporation.

Question 7

What is the function of the upper epidermis?

Answer 7

Transparent thin layer of cell with no chloroplasts that allow light to pass through.

Question 8

What is the function of the palisade mesophyll?

Answer 8

Cells that contain lots of chloroplasts and are closely packed together. Most photosynthesis takes place in these cells.

Question 9

What is the function of the spongy mesophyll?

Answer 9

Round cells that contain some chloroplasts but have air spaces between these cells to allow carbon dioxide to circulate and reach palisade cells.

Question 10

What is the function of the stomata?

Answer 10

Tiny pores that allow carbon dioxide and water vapour to diffuse in and out of the leaf.

Question 11

What is the function of the vein?

Answer 11

Contains xylem and phloem which supplies all parts of the plant with water and dissolved food that is produced.

Question 12

What is the function of the guard cell?

Answer 12

Cell with chloroplasts on the lower epidermis that control the opening and closing of the stomata.

Question 13

How is water transported in plants?

Answer 13

Water and minerals enter the plant through the root hair cells and are transported in dead xylem vessels.

Question 14

What is the function of the xylem?

Answer 14

Carries water and minerals up from the soil to the leaves for photosynthesis.

Question 15

Are the cells that form the xylem dead or alive?

Answer 15

Dead cells join together to form hollow tubes.

Question 16

What is a structural feature of the xylem?

Answer 16

Walls contain rings of lignin to withstand the pressure changes as water moves through the plant.

Question 17

How is sugar transported in plants?

Answer 17

Sugar is transported up and down the plant in the living phloem.

Question 18

What is the function of the phloem?

Answer 18

Carries dissolved food from the leaves, up and down the plant.

Question 19

Are the cells that form the phloem dead or alive?

Answer 19

Phloem cells are alive.

Question 20

What are two structural features of the phloem?

Answer 20

• Companion cell controls the phloem unit and provides energy
• Dissolved food is transported in the cytoplasm strands through the sieve plates from cell to cell

Question 21

What are the differences in transportation between the xylem and the phloem?

Answer 21

• In the xylem, water and minerals are transported
• In the phloem, food (sugar) is transported

Question 22

What are the differences in the direction of transportation between the xylem and the phloem?

Answer 22

• In the xylem, water and minerals are transported up
• In the phloem, food (sugar) is transported up and down

Question 23

What are the differences in the type of cell between the xylem and the phloem?

Answer 23

• In the xylem, the type of cell is dead
• In the phloem, the type of cell is living

Question 24

What are the differences in the structural features between the xylem and the phloem?

Answer 24

• In the xylem, it has rings of lignin
• In the phloem, it has sieve plates and companion cells

Question 25

What is transpiration?

Answer 25

Transpiration is the process of water moving through a plant and evaporating through the stomata (pores on a leaf).

Question 26

What are the stages of transpiration?

Answer 26

1. Water is absorbed by the roots 2. Absorbed water then travels through the plant xylem 3. Water evaporates from leaf's surface

Question 27

What are the factors that can affect the transpiration rate?

Answer 27

- Wind speed - Humidity - Temperature - Surface area

Question 28

Does wind speed increase or decrease the transpiration rate?

Answer 28

Increasing wind speed *increases* transpiration rate.

Question 29

Does humidity increase or decrease the transpiration rate?

Answer 29

Increasing humidity (water in the air) *decreases* transpiration rate.

Question 30

Does temperature increase or decrease the transpiration rate?

Answer 30

Increasing temperature *increases* transpiration rate.

Question 31

Does surface area increase or decrease the transpiration rate?

Answer 31

Increasing surface area *increases* transpiration rate.

Question 32

What is a bubble potometer?

Answer 32

A bubble potometer is used to measure the rate of water uptake by a leafy shoot. This is approximately equal to the rate of transpiration.

Question 33

How does a bubble potometer work?

Answer 33

An air bubble is allowed to enter the system and its movement is measure e.g. mm/min.

Question 34

When measuring the transpiration rate in a plant, what is one precaution and a reason for doing this, we could take for the experiment? - 1

Answer 34

Stem cut under water and end of stem, rubber tubing and capillary tubing all connected under water - to prevent air entering xylem and forming air locks.

Question 35

When measuring the transpiration rate in a plant, what is one precaution and a reason for doing this, we could take for the experiment? - 2

Answer 35

Tightly fitting rubber tubing used - to prevent leakage of water and ensure the system is airtight.

Question 36

When measuring the transpiration rate in a plant, what is one precaution and a reason for doing this, we could take for the experiment? - 3

Answer 36

Time allowed for plant to equilibrate between different environmental conditions - to ensure the rate of movement of the bubble is governed by the factor being investigated and not the previous one.

Question 37

When measuring the transpiration rate in a plant, what is one precaution and a reason for doing this, we could take for the experiment? - 4

Answer 37

Repeat measurements of the rate of movement of the bubble taken for each condition and average calculated - to obtain a more reliable result for each condition.

Question 38

When measuring the transpiration rate in a plant, what is one precaution and a reason for doing this, we could take for the experiment? - 5

Answer 38

All factors kept equal except for one change in environmental conditions - to ensure that the experiment is valid by only altering one variable factor at a time.

Question 39

What is a weight potometer?

Answer 39

- Another method to measuring transpiration is the weight potometer - You measure the weight at the start then at the end. The change in weight is a measure of transpiration - The greater the decrease in weight, the greater the transpiration (and vice versa)