Exam 3 - Plant Circulation and Gas Exchange

Question 1

What are the three basic plant organs and their functions?

Answer 1

• leaves: primary photosynthetic organs
• stem: contains vascular tissue for transport
• roots: specialized for anchorage, water scavenging, and mineral uptake

Question 2

What is the xylem?

Answer 2

vascular tissue that conducts water and dissolved minerals upward from roots into the shoots

Question 3

What is the phloem?

Answer 3

vascular tissue that transports sugars to the roots and other parts of the plant as needed

Question 4

How do roots and shoots rely on one another?

Answer 4

• roots have no chloroplasts and rely on shoots to supply products of photosynthesis for energy
• shoots rely on water and minerals supplied by roots

Question 5

What are the characteristics of water potential?

Answer 5

• determines direction of water movement
• water flows from regions of higher water potential to regions of lower water potential
• potential refers to water’s capacity to perform work

Question 6

What is turgor pressure?

Answer 6

pressure exerted by the protoplast against the plant cell wall

Question 7

Why can movement against the gradient occur in the phloem, but not in the xylem?

Answer 7

• xylem cells are dead and cannot produce energy to form a gradient
• phloem cells are alive and can produce energy to form a gradient

Question 8

What does a plant circulate through the phloem and xylum?

Answer 8

• sugars
• proteins
• secondary compounds
• hormones
• mRNA and miMRNA

Question 9

Where does gas exchange for photosynthesis occur?

Answer 9

stomata

Question 10

What is the gas exchange dilemma for plants?

Answer 10

• most of the water taken up by plants is lost to evaporation through the stomata, driving plants to close stomata
• plants need large amounts of atmospheric CO2, driving plants to open stomata
• plants must find a balance of opening and closing stomata that minimizes water losses while letting in adequate CO2

Question 11

What is the role of the stomata?

Answer 11

regulate the amount of gas exchange and water loss through transpiration

Question 12

What are the characteristics of guard cells?

Answer 12

• changes in turgor pressure can inflate/deflate guard cells and lead to changes in stomata size
• guard cell turgor pressure is controlled by K+ movement/regulation

Question 13

How does potassium relate to turgor pressure?

Answer 13

• K+ influx leads to increased turgor pressure

- K+ efflux leads to decreased turgor pressure

Question 14

How do plants exchange gas?

Answer 14

diffusion