Research Article Quiz 1

Question 1

Hypothesis

Answer 1

The primary cause of xylem dysfunction in these species during dehydration was the pulling of air through the pores in the cell walls of vessels as a result of high tensions on xylem water

Question 2

Vulnerability-to-Embolism Curves

Answer 2

(i) excised branches that were increasingly dehydrated in the lab
(ii) hydrated branches exposed to increasing levels of external air pressure

Question 3

Polystyrene Spheres

Answer 3

Perfused through hydrated stem segments to estimate the pore size in the vessel cell walls

Question 4

H. arbutifolia

Answer 4

smaller pores, narrower vessels, lower water potentials, lower transport efficiency

Question 5

M. laurina

Answer 5

wider pores, wider vessels, greater transport efficiency, deeper root system

Question 6

Transpiration

Answer 6

pulls liquid water from the soil, through the plant, and into the atmosphere as a water continuum

Question 7

Negative Pressure

Answer 7

evaporative pull of transpiration creates a tension on xylem water

Question 8

Pit Membrane

Answer 8

degraded primary cell wall containing pores that facilitate the passage of water between vessels while preventing air bubbles

Question 9

Cavitation

Answer 9

water in the xylem conduits comes under severe tension as a result of water stress

Question 10

Air-Seed Hypothesis

Answer 10

holds that air penetration through pores in the walls of vessels and tracheids is the cause of xylem dysfunction

Question 11

Trade-Off

Answer 11

when pore size decreases so does hydraulic conductivity

Question 12

Conclusion

Answer 12

M. laurana is more vulnerable to water-stress-induced embolism than H. arbutifolia

Question 13

Brink of Disaster

Answer 13

loss of hydraulic conductivity from one embolism increases xylem tension on other conducting vessels because fewer vessels are available for the same water requirement