3.3 Transport in plants

Question 1

What travels in the xylem?

Answer 1

water and soluble minerals

Question 2

What travels in the phloem?

Answer 2

assimilates, e.g sugars

Question 3

What are dicotyledonous plants?

Answer 3

Often flowering, have two seed leaves

Question 4

Where are the xylem and phloem stored in dicotyledonous plants?

Answer 4

In vascular bundles, often with other types of tissues such as collenchyma and sclerenchyma

Question 5

What is the sheath around the vascular bundle called?

Answer 5

Endodermis

Question 6

What cells do the endodermis contain?

Answer 6

A layer of meristem cells

Question 7

What is the layer of meristem cells in the root endodermis called?

Answer 7

The pericycle

Question 8

State the layers of the vascular bundle in the stem cross section

Answer 8

Xylem in the middle, phloem on the outside

Question 9

What is the role of lignin in the xylem?

Answer 9

strengthens the walls and keeps them open

Question 10

What 3 patterns are there of lignification in the xylem?

Answer 10

spiral, annular (rings) or reticular (network of broken rings)

Question 11

What are the gaps in xylem called?

Answer 11

bordered pits

Question 12

What are the adaptations of the xylem?

Answer 12

• one long column
• narrow so water column doesn’t break and capillary action can be effective
• bordered pits allow water movement out
• lignin patterns allow flexibility

Question 13

What is the barrier between the sieve elements called?

Answer 13

sieve plates

Question 14

What organelle do companion cells contain a lot of?

Answer 14

mitochondria to produce ATP

Question 15

What are gaps in the cell walls called?

Answer 15

plasmodesmata

Question 16

What is the pathway that only goes through the cell walls?

Answer 16

Apoplast

Question 17

What is the pathway that goes through the cytoplasm but not the vacuole?

Answer 17

Symplast

Question 18

What is the pathway that goes through the cytoplasm and vacuole?

Answer 18

Vacuolar

Question 19

a whole page on movement

Answer 19

more ions = lower water potential
flows from high to low

Question 20

Where is water lost during transpiration?

Answer 20

stomata and waxy cuticle

Question 21

What is the typical transpiration pathway?

Answer 21

xylem to spongy mesophyll to diffuse out of stomata

Question 22

Why is transpiration important?

Answer 22

helps to keep the flow of water which maintains plant health by transporting water and minerals around the plant

Question 23

What 4 factors affect transpiration rate?

Answer 23

• light intensity (more = more bc stomata open for photosynthesis)
• temperature (more = more because more kinetic energy)
• humidity (more = less)
• wind (more = more)
• water availability (less = less)

Question 24

What measures are taken to ensure the potometer is set up correctly?

Answer 24

• set up underwater to prevent air bubbles
• ensure shoot is healthy
• cut stem underwater to prevent air in the xylem
• cut stem at an angle for a large SA:V
• dry the leaves for maximum diffusion

Question 25

What is the equation for rate of transpiration?

Answer 25

pi x r^2 x Length

Question 26

What blocks the water in the apoplast pathway?

Answer 26

the casparian strip

Question 27

What happens when the water from the apoplast pathway is pushed into the cell?

Answer 27

transporter proteins attach to dissolved minerals to be transported into the medulla and xylem

Question 28

what happens when ions move into the medulla and xylem?

Answer 28

lower water potential in the xylem forces water in via osmosis

Question 29

What are the 3 ways water moves up the stem?

Answer 29

• root pressure (water pressure in the root forces it up the xylem)
• transpiration pull (cohesion in the water column called cohesion-tension theory)
• capillary action (water attracted to sides of xylem called adhesion)

Question 30

What is a xerophyte (plus examples)?

Answer 30

plant adapted to arid conditions (e.g cacti and marram grass)

Question 31

what is a hydrophyte (plus examples)?

Answer 31

adapted to live in water (e.g water lillies)

Question 32

What is translocation?

Answer 32

the transport of assimilates around the plant

Question 33

What is the process at the source?

Answer 33

hydrogen ions (H+) go from companion cell to leaf cell to actively transport sucrose in cotransport into sieve tube element

Question 34

What happens when the hydrogen ions with sucrose enter the phloem?

Answer 34

water goes down the water potential into the phloem, pressure builds up so moves to a low hydrostatic pressure .
sucrose moves into sink followed by water