Chapters 34-36 Flashcards
Where does most of the mass of a plant come from? (Hint: Where does it NOT come from?)
Most of the mass of a plant comes from atmosphere and water, not soil.
Define essential nutrient.
An element or compound required for normal growth and production.
Define macronutrients. What are macronutrients major components of in plants?
macronutrients are elements in the soil that plants require in large quantities. Major components of nucleic acids, phospholipids, and proteins.
What three macronutrients make up 96% of the dry weight of a plant?
The three are Carbon, Hydrogen, and Oxygen.
What are the three limiting macronutrients found in plants? (Hint: They are major ingredients of all fertilizers!)
Nitrogen, Phosphorus, Potassium.
What are some examples of micronutrients? What are some of their functions?
EX: iron, zinc, born, copper, and nickel. Some other functions are cofactors of specific enzymes.
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?
Water, air, and soil. - O,C,H
Macro- N, K, Ca, Mg, Phosphorus, Sulfur
Micro- Cl, Fe, Mn, Zn, Boron, Copper, Nickel, Molybdenum.
Explain how anions and cations behave differently. Which is more readily available for plant absorption, and why?
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
Explain cation exchange. What produces the H+ ions to help cation exchange?
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.
Define the zone of maturation.
The region just above the growing root tip
Define root hair’s function.
They increase the surface area available for nutrient and water absorption.
Explain how proton pumps generate an electrochemical gradient. What is the net charge both outside of the cell and inside of the cell?
Protons are pumped out of the cells —> outside of the cell becomes more positive.
The electrochemical gradient encourages cations to enter the cell. Explain how anions must enter the cell through cotransporters.
Anions can be cotransported against their electrochemical gradients.
Explain mycorrhizal fungi’s role in helping nutrient uptake in plants.
Mycorrhizal fungi increase plants surface area. Provide nitrogen and phosphorus(limiting factors) Fungi receive sugar from the plant.
Explain the interaction between nitrogen fixing bacteria and plants.
These nitrogen fixing bacteria convert N2 into ammonia, nitrates, and nitrites.
Name and describe the two plant vascular tissues.
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.
What is the xylem composed of?
Tracheids and vessel elements
What is the phloem composed of?
Sieve-tube elements and companion cells.
How does water flow through areas? (Hint: Low water potential to high? Or high to low?)
Water flows from areas of high water potential to lower.
Define solute potential and pressure potential.
Solute potential is the tendency of water to move by osmosis.
Pressure potential is the tendency of water to move due to pressure.
What is the equation for potential energy of water?
Trident= trident p + trident s
Explain how water is transported from the roots and the shoots, specifically through water potential.
Soil and roots have a high water potential. Warm dry air has low water potential.
Define translocation.
Translocation is the movement of sugars through a plant from sources to sinks via pholem.
Define source and sink. Give examples of sources and sinks on a plant.
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
Define phloem loading.
When sucrose is moved by active transport from source cells into pholem
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.)
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.
