Transport in Plants

Question 1

Define dicotyledonous

Answer 1

A dicotyledonous plant is a plant that has two budding leaves

Question 2

What is the series of transport vessels found in dicot plants called?

Answer 2

The vascular system

Question 3

What are the two main transport vessels in plants?

Answer 3

Xylem and Phloem tissue

Question 4

What is the parenchyma?

Answer 4

The packing and supportive tissue of a plant

Question 5

Where can we find vascular bundles in the root of the plant?

Answer 5

In the middle to help with tugging from the wind

Question 6

What are the two main functions of the xylem?

Answer 6

The transport of water and mineral ions
Support

Question 7

What is tannin and where is it founds

Answer 7

A bitter tasting chemical meant to deter predators, found in deposits in te parenchyma

Question 8

Because this is where water leaves the xylem.

Answer 8

Why are there areas of xylem wall that are not lignified?

Question 9

What are the main transporting vessels for the phloem?

Answer 9

the sieve tube elements

Question 10

What are the features of a mature sieve tube elements?

Answer 10

No nucleus or vacuole, a ‘sieve plate’ and filled with phloem sap.

Question 11

What is a plasomodesmata?

Answer 11

Microscopic channels that link cells

Question 12

What can we also find in the phloem with the sieve tube elements?

Answer 12

Companion cells- maintain nuclei and organelles and act as a life support system as phloem have lost most of their normal cell functions.

Question 13

What is hydrostatic pressure called in plants?

Answer 13

Turgor pressure

Question 14

How does water move into the roots?

Answer 14

The root hair cells:
-penetrate easily in soil particles
-large SA:V ratio
-thin surface layers
-solutes maintain a concentration gradient.

Question 15

Where is the symplast?

Answer 15

Continuous cytoplasm of cells through the plasmodesmata

Question 16

How does water move across the symplast pathway?

Answer 16

By osmosis- the next cell will have a lower water potential than the previous one

Question 17

Where is the apoplast?

Answer 17

In intracellular spaces and between cell walls.

Question 18

How does water move across the apoplast pathway?

Answer 18

Water is pulled in by osmosis and cohesive forces string more water molecules along behind it, creating a tension that means there is a flow of water.

Question 19

What is the Casparian strip?

Answer 19

A band of waxy suberin that runs about endodermal cells forming a waterproof layer, forcing water in the apoplast to join the symplast

Question 20

Where is the endodermis?

Answer 20

The layer of cells, surrounding vascular tissue.

Question 21

What is the purpose of the Casparian strip?

Answer 21

To force water into the cytoplasm, meaning it has to pass through selectively permeable membranes, excluding toxic solutes and pathogens from reaching tissues.

Question 22

What is root pressure?

Answer 22

The active pumping of minerals into the xylem to produce movement of water by osmosis, giving it a push up the xylem.

Question 23

How can a plant control water loss?

Answer 23

Opening and closing of the stomata

Question 24

Describe the path of the transpiration stream

Answer 24

Water enters the roots through osmosis and is transported up the xylem until it reaches the leaves. Here it moves by osmosis into the mesophyll air spaces. Water vapour moves out through the stomata.

Question 25

How is the transpiration pull supported?

Answer 25

Capillary action of the cohesion and adhesion of water molecules.

Question 26

Give three pieces of evidence for cohesion tension theory.

Answer 26

Changes in tree diameter
When xylem vessel is broken air is drawn in
If a xylem vessel is broken water can’t continue to move up the plants.

Question 27

What is a halophyte?

Answer 27

A plant adapted to live in conditions of high salt content

Question 28

What do a xerophyte?

Answer 28

A plant adapted to living in particularly dry conditions

Question 29

What is a hydrophyte?

Answer 29

A plant adapted to living in particularly wet habitats

Question 30

What are assimilates?

Answer 30

The products of photosynthesis transported in the phloem

Question 31

What is translocation and where does it occur?

Answer 31

The transport of organic compounds and nutrients in the phloem.

Question 32

What is the main assimilate?

Answer 32

Sucrose

Question 33

What are the main sources in a plant?

Answer 33

Green leaves and stems
Storage organs
Germinating food stores

Question 34

What are the main sinks in a plant?

Answer 34

Growing tips and shoots
Active meristem
Developing food stores

Question 35

How is sucrose moved into the cytoplasm in companion cells?

Answer 35

H+ ions are actively pumped out of the cell, and return using a co-transport protein with a sucrose molecule down a concentration gradient

Question 36

Why can the cotransport of sucrose lead to an increase of turgor pressure?

Answer 36

Because it decreases the water potential of the companion cells and water moves in.

Question 37

How is the phloem unloaded with sucrose?

Answer 37

Sucrose rapidly diffuses or converts to another molecule at the sink, allowing the sieve tube elements to maintain a steep concentration gradient.