Water Transport in Plants

Question 1

To provide mechanical support some cells within the stem must be?

Answer 1

Stiffened

Question 2

What are the three basic types of tissue found within plants?

Answer 2

Dermal tissue (epidermis), vascular tissue and ground tissue

Question 3

Some cells must allow water and minerals to pass from the roots to the leaves, what are the two types of cell designed o fulfil these functions?

Answer 3

Xylem vessels and sclerenchyma fibres

Question 4

What do the xylem vessels carry up through the stem?

Answer 4

Water and inorganic ions

Question 5

What does the phloem transport?

Answer 5

Sugars made by photosynthesis in the leaves

Question 6

What is lignin?

Answer 6

A polymer that impregnates the cellulose cell way and, as the cells become lignified, the entry of water and solutes into them is restricted making the cell waterproof

Question 7

What forms as a result of absent or perforated cell walls between cells?

Answer 7

The end cells of the columns are lost of become highly perforated, long tubes form as a result of this and are continuous from the roots of the plant to the leaves

Question 8

What happens during autolysis?

Answer 8

The tonoplast breaks down

Question 9

What is the result of autolysis?

Answer 9

The cell organelles, cytoplasm and cell surface membrane are broken down by the action of enzymes and are lost, leaving an empty tube

Question 10

Where does water evaporate from on a plant?

Answer 10

Mainly the leaves

Question 11

What surface does the majority of the evaporation occur from?

Answer 11

The surfaces of the cells that line the substomatal cavities in the leaves

Question 12

Where does water diffuse out through and is it up/down a diffusion gradient?

Answer 12

Through the stomata, down a diffusion gradient

Question 13

What is water evaporating through the stomata known as?

Answer 13

Transpiration

Question 14

What is water leaving the plant replaced by?

Answer 14

Water absorbed through the roots of the plant

Question 15

What do the minute channels between the cellulose microfibrils act as?

Answer 15

Tiny capillaries, drawing water up the plant by capillary action

Question 16

How is capillary action caused?

Answer 16

By surface tension

Question 17

The continuos stream of water being drawn up the xylem vessels and through the cell walls within the leaf is known as the?

Answer 17

Transpiration stream

Question 18

Where does the energy for this process come from?

Answer 18

The sun

Question 19

When water is drawn up the plant it is under?

Answer 19

Tension

Question 20

Why does the column of water not break when it is pulled up the plant?

Answer 20

Because of the cohesive forces between the water molecules

Question 21

Cohesion is brought about through the formation of?

Answer 21

Hydrogen bonds

Question 22

How can hydrogen bonds be formed in water?

Answer 22

Because water is polar

Question 23

Adhesion is brought about when?

Answer 23

Hydrogen bonds form between water molecules and the -OH groups of the cellulose molecules of cell walls

Question 24

Because water is linked by cohesion and pulled up under tension, this concept of water movement is known as?

Answer 24

Cohesion-tension theory

Question 25

Hydrogen bonding between water molecules result in strong/weak cohesive forces? Why is this beneficial?

Answer 25

Strong cohesive forces that keep the water together as a continuous column in xylem vessels

Question 26

What do the solvent properties of water mean that can happen?

Answer 26

Dissolved substances can be transported around plants freely in the xylem and phloem. The synthesis of sugars from water and CO2 in photosynthesis is important to plants

Question 27

What thermal properties does water have in plants?

Answer 27

It warms up and cools down slowly. This is useful to organisms helping them to avoid rapid changes in their internal temperatures

Question 28

How can plants survive in extremely cold temperatures?

Answer 28

Ice floats as water expands when it freezes, this enables organisms to survive in liquid water under ice in frozen ponds etc.

Question 29

The movement of water through the xylem provides a ? for the transport of ?

Answer 29

Mass flow system, inorganic ions

Question 30

Why are nitrate ions needed by plants?

Answer 30

To make amino acids which each contain one or more nitrogen atom

Question 31

What does a nitrate ion deficiency cause?

Answer 31

Yellow leaves

Question 32

Why is magnesium needed by plants?

Answer 32

Magnesium makes chlorophyll, giving leaves their green colour

Question 33

What does a magnesium deficiency cause?

Answer 33

The older leaves become yellow

Question 34

Why are calcium ions needed by plants?

Answer 34

They have a role in the structure of the cell wall and in the permeability of the cell membrane

Question 35

What does a calcium ion deficiency cause?

Answer 35

Stunted growth

Question 36

Lignin not only waterproofs the cell walls, it also ?

Answer 36

Makes them much stiffer giving the plant greater tensile strength

Question 37

How is lignin laid down?

Answer 37

In spirals or rings

Question 38

What two places in the stem are lignified?

Answer 38

The xylem and sclerenchyma fibres

Question 39

What happens to sclerenchyma fibres once lignified?

Answer 39

They die, leaving hollow fibres that are strong

Question 40

What else does a plant stem rely on for support?

Answer 40

Tightly packed, fully turgid parenchyma cells to maintain its shape and keep it errect

Question 41

What is a turgid cell?

Answer 41

One that is completely full, turgor supports the leaves of all plants and if lost, the plant wilts.