Chapters 34-36

Question 1

Where does most of the mass of a plant come from? (Hint: Where does it NOT come from?)

Answer 1

Most of the mass of a plant comes from atmosphere and water, not soil.

Question 2

Define essential nutrient.

Answer 2

An element or compound required for normal growth and production.

Question 3

Define macronutrients. What are macronutrients major components of in plants?

Answer 3

macronutrients are elements in the soil that plants require in large quantities. Major components of nucleic acids, phospholipids, and proteins.

Question 4

What three macronutrients make up 96% of the dry weight of a plant?

Answer 4

The three are Carbon, Hydrogen, and Oxygen.

Question 5

What are the three limiting macronutrients found in plants? (Hint: They are major ingredients of all fertilizers!)

Answer 5

Nitrogen, Phosphorus, Potassium.

Question 6

What are some examples of micronutrients? What are some of their functions?

Answer 6

EX: iron, zinc, born, copper, and nickel. Some other functions are cofactors of specific enzymes.

Question 7

What are the three sources nutrients can be obtained from? In which source is oxygen, carbon, and hydrogen obtained from? In which are the other macronutrients obtained
from? The micronutrients?

Answer 7

Water, air, and soil. - O,C,H
Macro- N, K, Ca, Mg, Phosphorus, Sulfur
Micro- Cl, Fe, Mn, Zn, Boron, Copper, Nickel, Molybdenum.

Question 8

Explain how anions and cations behave differently. Which is more readily available for plant absorption, and why?

Answer 8

Anions tend to dissolve in soil water - easier plant absorption
Cations tend to interact with negative charges of organic matter and clay. - harder to absorb

Question 9

Explain cation exchange. What produces the H+ ions to help cation exchange?

Answer 9

When protons bind to negative charges on soil particles. Plant roots real ease CO2, which interacts with H2O forming Carbonic acid which releases H+ enabling uptake of cations.

Question 10

Define the zone of maturation.

Answer 10

The region just above the growing root tip

Question 11

Define root hair’s function.

Answer 11

They increase the surface area available for nutrient and water absorption.

Question 12

Explain how proton pumps generate an electrochemical gradient. What is the net charge both outside of the cell and inside of the cell?

Answer 12

Protons are pumped out of the cells —> outside of the cell becomes more positive.

Question 13

The electrochemical gradient encourages cations to enter the cell. Explain how anions must enter the cell through cotransporters.

Answer 13

Anions can be cotransported against their electrochemical gradients.

Question 14

Explain mycorrhizal fungi’s role in helping nutrient uptake in plants.

Answer 14

Mycorrhizal fungi increase plants surface area. Provide nitrogen and phosphorus(limiting factors) Fungi receive sugar from the plant.

Question 15

Explain the interaction between nitrogen fixing bacteria and plants.

Answer 15

These nitrogen fixing bacteria convert N2 into ammonia, nitrates, and nitrites.

Question 16

Name and describe the two plant vascular tissues.

Answer 16

Xylem, conducts water and dissolved ions from root system to shoot system.
Pholem, conducts sugar, amino acids, chemical signals, and other substances back and fourth between the root system and shoot system.

Question 17

What is the xylem composed of?

Answer 17

Tracheids and vessel elements

Question 18

What is the phloem composed of?

Answer 18

Sieve-tube elements and companion cells.

Question 19

How does water flow through areas? (Hint: Low water potential to high? Or high to low?)

Answer 19

Water flows from areas of high water potential to lower.

Question 20

Define solute potential and pressure potential.

Answer 20

Solute potential is the tendency of water to move by osmosis.
Pressure potential is the tendency of water to move due to pressure.

Question 21

What is the equation for potential energy of water?

Answer 21

Trident= trident p + trident s

Question 22

Explain how water is transported from the roots and the shoots, specifically through water potential.

Answer 22

Soil and roots have a high water potential. Warm dry air has low water potential.

Question 23

Define translocation.

Answer 23

Translocation is the movement of sugars through a plant from sources to sinks via pholem.

Question 24

Define source and sink. Give examples of sources and sinks on a plant.

Answer 24

Source is the tissue where sugar enters the pholem
Sink is the tissue where sugar exits the pholem.
Sinks ex: flower, roots
Sources ex: stem

Question 25

Define phloem loading.

Answer 25

When sucrose is moved by active transport from source cells into pholem

Question 26

Explain water movement in and out of the xylem according to the level of sucrose in the phloem. (Hint: Water will leave the xylem when it’s near high concentrations of sucrose.)

Answer 26

Water from adjacent xylem vessels passively moves into the pholem. As the concentration of sucrose decreases in the pholem water flows back into the xylem.