Transport in Plants

Question 1

How does water enter plants and what is its path?

Answer 1

enters roots, then moves to xylem, water rises through xylem, water sexist through stomata in leaves

Question 2

How does water travel such great distance in plants?

Answer 2

some “pushing” from pressure of water entering roots, most of the force is “pulling” created by transpiration

Question 3

What is xylem transport driven by?

Answer 3

transpiration (mostly) and root pressure

Question 4

What is root pressure caused by?

Answer 4

continuous accumulation of ions in the roots (at night when transpiration is low)

Question 5

What is guttation?

Answer 5

production of dew is water loss of water from leaves when root pressure is high

Question 6

What are aquaporins?

Answer 6

speed up osmosis but do not change direction of water movement

Question 7

What are essential for bulk transport of minerals?

Answer 7

tracheids and vessels

Question 8

What 3 transport routes exist through cells?

Answer 8

apoplast route, symplast route, and transmembrane route

Question 9

What is the apoplast route?

Answer 9

movement though the cell walls and space between cells, avoids membrane transport

Question 10

What is the symplast route?

Answer 10

cytoplasm continuum between cells connected by plasmodesmata

Question 11

What is the transmembrane route?

Answer 11

membrane transport between cells and across membranes of vacuoles within cells, permits greatest control

Question 12

What is cavitation?

Answer 12

air bubble can break tensile strength of water column, gas-filled bubble can expand and block tracheid or vessel, damage can be minimized by anatomical adaptations

Question 13

T/F The stomata must be open at least part of the time to allow carbon dioxide entry?

Answer 13

True

Question 14

What are guard cells?

Answer 14

epidermal cells containing chloroplasts, have thicker cell walls inside and thinner cell walls elsewhere which cause to bulge and bow outward when they become turgid and cause stomata to open, turgor in guard cells results from active uptake of potassium chloride and malate (water enters osmotically)

Question 15

When do transpiration rates increase?

Answer 15

temperature and wind velocity because water molecules evaporate more quickly

Question 16

What are some ways that plants limit water loss during drought conditions?

Answer 16

dormancy, loss of leaves, covering leaves with cuticle and wooly trichomes, reducing number of stomata, having stomata in pits on leaf surface

Question 17

What is flooding?

Answer 17

deplete available oxygen, leads to abnormal growth

Question 18

What is a lenticel?

Answer 18

spongy area in the cork surfaces of stem, roots, and other plant parts that allow interchange of gases between internal tissues and the atmosphere through the periderm

Question 19

What are pneumatophores?

Answer 19

long, spongy air-filled roots that emerge above the mud

Question 20

What do sinks include?

Answer 20

growing root and stem tips as well as developing fruits

Question 21

What is the purpose of having palisade mesophyll near the top of the leaf and having stomata on the bottom?

Answer 21

1. loose palisade layer allows gas exchange to occur rapidly, stomata are on bottom to allow diffusion of air upwards 2. stomata can only differentiate bottom because UV radiation impedes their development, palisade layer helps shelter them 3. palisade cells control development of stomata on bottom of leaf through gravitational dispersal of hormones 4. tight-fitting palisade cells prevent water loss from hot surfaces of leaves, stomata allow gas exchange on bottom leaf, where it’s cooler and therefore has less water loss 5. stomata are on the top of the leaf while the palisade layer lines the bottom