Notes 7

Question 1

What is the A horizon?

Answer 1

The A horizon (topsoil) is a mix of broken down rock, living organisms, and decaying organic matter.

Question 2

What is the B horizon?

Answer 2

The B horizon has less organic matter and is less weathered.

Question 3

What is the C horizon?

Answer 3

The C horizon is mostly broken rock. Serves as the parent material for inorganic minerals that will help for the upper horizons.

Question 4

Most soil particles are ___ charged so they hold onto ____ charged ions.

Answer 4

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

Question 5

Roots cant absorb mineral cations directly, so they must ____?

Answer 5

Be in the soil solution.

Question 6

How do roots acidify the soil solution?

Answer 6

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.

Question 7

The organic layer of soil is made by what?

Answer 7

The organic layer (humus) is made by an array of decomposers (worms,insects, fungi, bacteria). They break down dead leaves, feces, etc

Question 8

How is soil formed?

Answer 8

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

Question 9

What is the green revolution?

Answer 9

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%

Question 10

What are some downstream effects of fertilizers?

Answer 10

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.

Question 11

What are the major components of organic tissues/compounds?

Answer 11

Carbon (CO2) oxygen(O2) and hydrogen (H2O)

Question 12

What element is a component of nucleic acids, proteins, chlorophyll?

Answer 12

Nitrogen (NO3-, NH4+)

Question 13

What is a cofactor of many enzymes, functions in water balance (operation of stomata)?

Answer 13

Potassium (K+)

Question 14

What is a component of cell walls, maintains membrane functions, and signal transduction?

Answer 14

Calcium(Ca2+)

Question 15

What is a component of chlorophyll, a cofactor in many enzymes?

Answer 15

Magnesium (Mg2+)

Question 16

What is a component of nucleic acids, phospholipids and ATP?

Answer 16

Phosphorus (H2PO4-, HPO42-)

Question 17

What is a component of proteins?

Answer 17

Sulphur (SO42-)

Question 18

Whats the purpose of roots?

Answer 18

Roots anchor the plant, absorb water, minerals, and store carbs.

Question 19

What is the purpose of stems?

Answer 19

Stem separates leaves, raises reproductive structure

Question 20

What are leaves?

Answer 20

Photosynthetic organs

Question 21

Most monocots have a ____ root system.

Answer 21

Fibrous. Primary (first) root dies early, many small roots (adventitious roots) emerge from the stem.

Question 22

Each root forms ______ which further branch, holding soil in place.

Answer 22

Lateral roots.

Question 23

Most absorption of water and minerals occurs near ____.

Answer 23

Root tips

Question 24

The root surface of a typical tree is ____ than the surface area of the crown.

Answer 24

Larger, 4-7 times bigger

Question 25

What is the nutrient cycle?

Answer 25

The nitrogen cycle is making N2 in the atmosphere to NO3- so it can be used by plants.

Question 26

The nitrogen cycle turns N2 into NO3- by what?

Answer 26

• 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.

Question 27

Nitrogen fixing bacteria can have what kinds of lifestyles?

Answer 27

Nitrogen fixing bacteria can be free living, aquatic, symbiotic with root nodules, or symbiotic with mycorrhizal fungi.

Question 28

How does the nitrogen cycle work?

Answer 28

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.

Question 29

How do free living bacteria obtain their own energy?

Answer 29

Decomposition

Question 30

Free living bacteria fix nitrogen under ____ conditions.

Answer 30

Anaerobic.

Question 31

T or F: Free Living cyanobacteria can photosynthesize because they contain chloroplast.

Answer 31

True

Question 32

Free living area around a root hair is ____ oxygen so they do ___ respiration

Answer 32

Low, anaerobic.

Question 33

Symbiotic areas are living in nodules and in ___ oxygen area so they do ____ respiration.

Answer 33

High, aerobic

Question 34

What are rhizobia bacteria?

Answer 34

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.

Question 35

Whats the purpose of rhizobium?

Answer 35

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

Question 36

How does the growing of root nodules work?

Answer 36

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.

Question 37

T or F: It is unbeneficial to have mycorrhizal fungi.

Answer 37

False. It is beneficial.

Question 38

Ectomycorrhizae grows on the _____ of roots and forms ______.

Answer 38

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)

Question 39

Arbuscular mycorrhizae (Endomycorrhizae) grows on the ___ of roots.

Answer 39

Arbuscular mycorrhizae (Endomycorrhizae) grows out the inside of roots. About 85% of species have arbuscular mycorrhizae, mostly crop plants.

Question 40

How does nitrogen move through ecosystems?

Answer 40

Nitrogen moves ecosystems anthropogenically (human activity) and naturally (eating, feces).