Water

Question 1

What is the result of more free water molecules?

Answer 1

Compared to suite, the higher the water potential

Question 2

Why is water important?

Answer 2

A key substance for plants both metabolism and structure

Question 3

What does water provide?

Answer 3

Turgor (hydrostatic) pressure

Question 4

What is the result of turgor?

Answer 4

It provides a hydrostatic skeleton to support stems and leaves

Question 5

What is water vital for?

Answer 5

Cell expansion

Question 6

How is water vital for cell expansion?

Answer 6

The force allows roots to push through soil and shoots to grow through concrete and tarmac

Question 7

What are other uses of water?

Answer 7

Keep plants cool, transport and photosynthesis

Question 8

How is water used to keep plants cool?

Answer 8

Loss of water by evaporation from the stomata in leaves

Question 9

How is water used in transport?

Answer 9

Mineral ions and products of photosynthesis are transport in aqueous solutions

Question 10

How is water used in photosynthesis?

Answer 10

It is one of the raw materials

Question 11

What is the function of the root?

Answer 11

To anchor plant and provide surface for uptake of water from soil

Question 12

How does the root increase SA for water uptake?

Answer 12

Present of root hairs just behind root tip

Question 13

How are root hairs a well adapted exchange surface?

Answer 13

Microscopic size, large SA:V, thin SA for diffusion and osmosis, and cytoplasm solute

Question 14

What is the function of the microscopic size of a root hair?

Answer 14

It can penetrate between soil particles

Question 15

How do root hairs have a large SA?

Answer 15

1000s grow on root tips

Question 16

What is the function of cytoplasm solute?

Answer 16

It maintains water potential gradient between soil, water and cell as ions can be moved into the root hair cell by active transport

Question 17

How does water move into the root?

Answer 17

Through cytoplasm and sap in root hair cell and from soil water

Question 18

What is the cytoplasm and sap in root hair cell?

Answer 18

Sugar, mineral ions and amino acids with low water potential

Question 19

What is soil water?

Answer 19

A very low concentration of mineral ions with high water potential

Question 20

How do mineral ions and water move into root hair cells?

Answer 20

By active transport when in short supply and then water follows by osmosis

Question 21

What are the 2 ways water moves across the root?

Answer 21

The apoplast or symplast pathway

Question 22

What is the apoplast pathway?

Answer 22

Water moves through the open network of cellulose fibres in the cell walls through intercellular spaces

Question 23

What is the resistance in apoplast pathway?

Answer 23

Little resistance to the movement

Question 24

How does water move into the xylem?

Answer 24

As water moves into the xylem, other water molecules are pulled along behind across the movement in a continuous flow

Question 25

What allows the continuous flow of water?

Answer 25

Cohesive forces joining water molecules together

Question 26

What is the symplast pathway?

Answer 26

Water moves through the cytoplasm from one cell to the next through the plasmodesmata

Question 27

How does water move from cells?

Answer 27

It moves by osmosis from one cell to the next across the root until it reaches the endodermis

Question 28

What happens when water leaves a cell?

Answer 28

The water potential gets lower, maintaining the water potential for the next water molecules to come into cell

Question 29

What is the effect of plasmodesmata?

Answer 29

The cytoplasm is continuous

Question 30

What is the endodermis?

Answer 30

A ring of cells surrounding xylem and phloem

Question 31

What is the casparian strip?

Answer 31

A strip of wax (suberin) embedded in the cell walls of the endodermis and is impermeable to water

Question 32

What is the function of the casparian strip?

Answer 32

It blocks to apoplast pathway

Question 33

How does water move from the apoplast pathway to the symplast pathway?

Answer 33

The water in the apoplast pathway is diverted across the plasma membrane and into the cytoplasm where it travels through the symplast pathway

Question 34

What does water cross when it moves pathway?

Answer 34

A partially permeable membrane which has selective carrier proteins to prevent toxins reaching other parts of the plant

Question 35

What is the function of the endodermis?

Answer 35

It moves minerals by active transport from the cortex into the xylem

Question 36

What is the result of the endodermis?

Answer 36

Water potential in xylem becomes more negative and water passes into the xylem from cortex by osmosis down water potential gradient

Question 37

How is the water potential set up from soil to xylem?

Answer 37

Water potential in cells outside the endodermis goes down and water i pulled in from the next layer of cells right away across the root so water enters root hairs by osmosis

Question 38

What is the result of active transport of minerals?

Answer 38

Resulting movement of water by osmosis into the xylem results in root pressure

Question 39

What is root pressure?

Answer 39

A positive hydrostatic pressure which in independent of transpiration

Question 40

What is the result of root pressure?

Answer 40

Water is pushes a little way up the xylem

Question 41

What is evidence for root pressure?

Answer 41

If the shoot of a plant is cut off, sap exudes from the stump, guttation, mitochondrial poisons, lack of oxygen and increased temperature

Question 42

What is guttation?

Answer 42

Leave tips exude sap overnight

Question 43

How is mitochondrial poisons evidence for root pressure?

Answer 43

Mitochondrial poisons such as cyanide which prevents production of ATP, result in loss of root pressure

Question 44

What happens due to a lack of oxygen?

Answer 44

Loss of root pressure

Question 45

How does temperature affect root pressure?

Answer 45

Root pressure rises, suggesting chemical reactions