Notes 7 Flashcards
What is the A horizon?
The A horizon (topsoil) is a mix of broken down rock, living organisms, and decaying organic matter.
What is the B horizon?
The B horizon has less organic matter and is less weathered.
What is the C horizon?
The C horizon is mostly broken rock. Serves as the parent material for inorganic minerals that will help for the upper horizons.
Most soil particles are ___ charged so they hold onto ____ charged ions.
Most soil particles are negatively charged so they easily hold onto positively charged ions such as potassium, calcium, and magnesium. Negative charged ions such as nitrate phosphate and sulfate do not bind to soil and can easily be lost by leaching
Roots cant absorb mineral cations directly, so they must ____?
Be in the soil solution.
How do roots acidify the soil solution?
Roots acidify the soil solution by releasing CO2 from respiration and pumping H+ into the soil. CO2 reacts with H2O to form H2CO3 which releases H+ into the soil.
H+ ions in the soil solution neutralize the negative charges of soil particles, causing a release of mineral cations into the soil solution, where they can be absorbed by the roots.
The organic layer of soil is made by what?
The organic layer (humus) is made by an array of decomposers (worms,insects, fungi, bacteria). They break down dead leaves, feces, etc
How is soil formed?
First rain causes bedrock to disintegrate, then simple organisms and organic matter make their way into the C horizon. Next the defined horizons form as more material and life forms, and lastly their is well developed soil. This process takes years
What is the green revolution?
The green revolution is the modernization of farming beginning in the 1950s. It lifted millions of people globally out of starvation and the harvest of staple crops more than doubled between 1961-1985. Global grain harvest increased by 160%
What are some downstream effects of fertilizers?
Downstream effects of fertilizer are that they may run off fields if they have lots of water, which then leads to lots of algae growth (algae bloom). Takes up too much nutrients for other organisms and can cause areas of the bay or lake that become dead. Lake Erie has been declared dead 3 times.
What are the major components of organic tissues/compounds?
Carbon (CO2) oxygen(O2) and hydrogen (H2O)
What element is a component of nucleic acids, proteins, chlorophyll?
Nitrogen (NO3-, NH4+)
What is a cofactor of many enzymes, functions in water balance (operation of stomata)?
Potassium (K+)
What is a component of cell walls, maintains membrane functions, and signal transduction?
Calcium(Ca2+)
What is a component of chlorophyll, a cofactor in many enzymes?
Magnesium (Mg2+)
What is a component of nucleic acids, phospholipids and ATP?
Phosphorus (H2PO4-, HPO42-)
What is a component of proteins?
Sulphur (SO42-)
Whats the purpose of roots?
Roots anchor the plant, absorb water, minerals, and store carbs.
What is the purpose of stems?
Stem separates leaves, raises reproductive structure
What are leaves?
Photosynthetic organs
Most monocots have a ____ root system.
Fibrous. Primary (first) root dies early, many small roots (adventitious roots) emerge from the stem.
Each root forms ______ which further branch, holding soil in place.
Lateral roots.
Most absorption of water and minerals occurs near ____.
Root tips
The root surface of a typical tree is ____ than the surface area of the crown.
Larger, 4-7 times bigger
What is the nutrient cycle?
The nitrogen cycle is making N2 in the atmosphere to NO3- so it can be used by plants.
The nitrogen cycle turns N2 into NO3- by what?
- lightening
-ammonification: animals decay or produce feces, the decomp process takes nitrogen and interacts with H+ ions in soil to make NH4+, breaks down easily into NO2- which then converts to NO3-
-nitrogen fixing bacteria: they take N2 from the atmosphere and convert it to NH3, pass it to nitrifying bacteria which make it NO3-. Denitrification bacteria then change NO3- to N2 and put it back into the atmosphere.
Nitrogen fixing bacteria can have what kinds of lifestyles?
Nitrogen fixing bacteria can be free living, aquatic, symbiotic with root nodules, or symbiotic with mycorrhizal fungi.
How does the nitrogen cycle work?
First nitrogen fixing bacteria convert atmospheric nitrogen to ammonia (NH3). Then NH3 picks up an extra H+ ion to become NH4+ which oxidizes by nitrifying bacteria to nitrite (NO2-) and then nitrate (NO3-). Then roots absorb nitrate (NO3-), and a plant enzyme reduces it back to NH4+ which other enzymes then convert to amino acids. The ammonifying bacteria converts amino acids from decomposing organic material to ammonium (NH4). Denitrifying bacteria contributes to some soil nitrogen loss by converting nitrate back to N2.
How do free living bacteria obtain their own energy?
Decomposition
Free living bacteria fix nitrogen under ____ conditions.
Anaerobic.
T or F: Free Living cyanobacteria can photosynthesize because they contain chloroplast.
True
Free living area around a root hair is ____ oxygen so they do ___ respiration
Low, anaerobic.
Symbiotic areas are living in nodules and in ___ oxygen area so they do ____ respiration.
High, aerobic
What are rhizobia bacteria?
Rhizobia bacteria (symbiotic) are gram neg bacteria that are flagellated and motile. They are rod shaped and 0.8um in diameter and 2um in length. They have the ability to fix nitrogen and evolve at several points in domain bacteria.
Whats the purpose of rhizobium?
Rhizobium is associated with the roots of legumes, they contain nutrients from the host plant (heterotrophic). They convert atmospheric nitrogen to NH3 or NO3- which the plant can then absorb
How does the growing of root nodules work?
First chemical signals attract bacteria and an infection thread forms. Bacteroid form and growth continues until a root nodule forms. The nodule develops vascular tissue and the mature nodule grows to be many times the diameter of the root.
T or F: It is unbeneficial to have mycorrhizal fungi.
False. It is beneficial.
Ectomycorrhizae grows on the _____ of roots and forms ______.
Ectomycorrhizae grows on the outside of roots and forms fungal sheaths. Only 10% of plant families have species that form ectomycorrhizae. Mostly wood plants (pine, oak, birch)
Arbuscular mycorrhizae (Endomycorrhizae) grows on the ___ of roots.
Arbuscular mycorrhizae (Endomycorrhizae) grows out the inside of roots. About 85% of species have arbuscular mycorrhizae, mostly crop plants.
How does nitrogen move through ecosystems?
Nitrogen moves ecosystems anthropogenically (human activity) and naturally (eating, feces).
