Chapter 36

Question 1

xylem

Answer 1

a transport tissue in vascular plants which transports water from roots to leaves

Question 2

phloem

Answer 2

the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as photosynthates, in particular the sugar sucrose, to parts of the plant where needed. This transport process is called translocation.

Question 3

apoplastic

Answer 3

space outside the plasma membrane within which material can diffuse freely. The apoplastic route facilitates the transport of water and solutes across a tissue or organ. This process is known as apoplastic transport.

Question 4

symplastic

Answer 4

he inner side of the plasma membrane in which water and low-molecular-weight solutes can freely diffuse. Symplast could also refer to the cytoplasmic connection made between cells by the plasmodesmata.

Question 5

plasmodesmata

Answer 5

allows the direct flow of small molecules such as sugars, amino acids, and ions between cells. Larger molecules, including transcription factors and plant viruses, can also be transported through with the help of actin structures.

Question 6

casparian strip

Answer 6

a band-like thickening in the center of the root endodermis (radial and cell walls) of vascular plants (Pteridophytes and Spermatophytes). The composition of the region is mainly lignin, and its width varies between species.

Question 7

Psi Ψ

Answer 7

the gravity potential - Water potential is a measure of the potential energy in water as well as the difference between the potential in a given water sample and pure water. Water always moves from the system with a higher water potential to the system with a lower water potential.

Question 8

bulk flow

Answer 8

process by which proteins travel throughout different areas of the plant

Question 9

do stomata increase plant productivity?

Answer 9

yes - because they are responsible for gas exchange

Question 10

is stomata density related to CO2 concentration in the air?

Answer 10

yes -

Question 11

are stomata open or closed at night?

Answer 11

closed at night because they cannot perform photosynthesis

Question 12

why is stomata density higher on the underside of leaves?

Answer 12

so that they dont lose too much water

Question 13

which reflects the correct relationship of water potentials for a typical tree on a sunny day?

• Leaf Ψ < trunk Ψ < soil Ψ
• outside air Ψ> leaf mesophyll Ψ< root Ψ
• leaf Ψ> trunk Ψ> soil Ψ
• soil Ψ< root Ψ > leaf Ψ
• none of the above

Answer 13

• Leaf Ψ < trunk Ψ < soil Ψ

Question 14

the basis of the pull generated by transpiration in the xylem is ____.

Answer 14

negative pressure at the air-water interface in the leaf

Question 15

water can follow two pathways in plants, apoplastic and symplastc. How do these pathways differ?

Answer 15

the apoplastic route is entirely external to cell membranes; the symplastic route is inside of cells

Question 16

transport of xylem sap involves ___

Answer 16

transpiration - evaporation of water from plant’s surface ; negative pressure

Question 17

water flows from root to cortex which generates ____

Answer 17

root pressure, a push of xylem sap ; positive pressure - at night root cells lower water potential by actively pumping mineral ions into the xylem

Question 18

cohesion-tension hypothesis for xylem sap

Answer 18

transpiration provides the pull for the ascent of xylem sap and water cohesion transmits this pull along the entire length of the xylem from shoots to roots; xylem sap is normally under negative pressure or tension

Question 19

Which of the following statements does NOT describe a function resulting from the action of guard cells?

• lowering the loss of water upon detecting certain signals from water-stressed roots
• keeping leaves at a more positive water potential relative to roots
• allowing an optimal rate of photosynthesis to occur by letting CO2 enter the leaf
• permitting cooling of the leaf by evaporative loss of water
• allowing water to exit the leaf and so generating tension in the xylem tissue

Answer 19

keeping leaves at a more positive water potential relative to roots

Question 20

water potential gradient

Answer 20

water potential decreases as you go further from the routes

Question 21

mechanisms of stomatal opening and closing

Answer 21

the stomatal opening and closing depending on the generation of a potassium ion gradient. ATP produced in the guard cells during photosynthesis is utilized to pump the potassium ions of the adjacent cells into the guard cells.
An increase in K+ion concentration in the guard cells makes them hypertonic, so more water is drawn inside the cells. Thus, the guard cells become turgid, widening the stomatal opening

Question 22

if a potato tuber sends sugar to the rest of the plant during spring but receives sugar from the rest of the plant during summer, it moves from being _____

Answer 22

a source to a sink

Question 23

translocation

Answer 23

the process by which products of photosynthesis are transported through the phloem

Question 24

with sunny, warm, dry, and windy conditions the transpiration rates will ____

Answer 24

increase

Question 25

_____ protects leaves from overheating by lowering the internal temperature through evaporative cooling

Answer 25

transpiration

Question 26

sugar source

Answer 26

an organ that is a net producer of sugar

Question 27

sugar sink

Answer 27

an organ that is a net consumer or depository of sugar, such as roots, buds, and fruits

Question 28

Sugar maples are tapped for their sugar-rich sap in the early spring. This sap is transported in ______ and is moving from the ______.

Answer 28

phloem; routes