Unit A: Energy Exchange & Matter Exchange in the Biosphere

Sections 2.1-2.3

What are the properities of water?

(Boiling and freezing points, universal solven, density of water, heat capacity)

A polar molecule, one end of a water molecule is lsightly positive (hydrogen end), and one end is slightly negative (oxygen end) - can have an attraction to each other - hydrogen bonding

High boiling and freezing points - can exist in all three states

Universal Solvent - can dissolve many molecular and most ionic compounds

Density of water - Liquid water is more dence than solid water (ice). Most dense at 4 degrees

Specifc heat capacity - Needs huge amounts of kinetic energy - water can hold and absorb large amounts of enery without itself changing temperature a great deal - Takes in heat when it’s hot and releasing heat when it’s hot

What is Cohesion?

The attraction of water molecules - creates surface tension

What is Adhesion?

The attraction of water molecules to other molecules - allows water to stick to other substances

What are the 2 major functions of the water cycle?

Distribution - Water is distributed by weather patterns and other processes throughout the biosphere

Cleaning - Evaporation cleans the water by the process of distilation

What is use for carbon?

The key element of all living things

Organic carbon is stored in the bodies/tissues/cells of all living things

How is carbon being rapidly cycled?

Photosynthesis - plants taking in carbon dioxide and water to conver them into usable products (stored as starch, cellulose, and sugars)

Cellular respiration - carbon products used to create carbon dioxide and water (carbon is returned into the atmosphere)

Decomposition - after organisms die, carbon stored in their tissue gets returned back into the cycle.

How is carbon being slowly cycled?

Stored long-term in the ocean - earth’s largest carbon sink, 48% of carbon dioxide is disolved into water

Earth’s crust - sedimentary rock layers - when aquatic organisms die the carbon trapped in their tissues become apart of ocean sediment (trapped for milions of years as rock or fossil fuel

Limestone stores tons of carbon - fromed from shells/disollved calcium carbonate in water

Forests - Trees take in/remove carbon dixoide from the atmosphere - can only be released when the tree dies or bruns.

How is carbon important for greenhouse gases? What is the enhanced greenhouse effect?

Helps to trap some of the sun’s solar radiation

Excess carbon can cause the enhanced greenhouse effect - mining/drilling for fossil fuels, and clear cutting/deforestation can cause the build up of carbon dioxide

How is sulfur important?

Helps with the production of proteins, amino acids, and vitamins

Plants and algae need sulfer to form sulfate for proper growth - soluble in water

How is sulfur rapidly cycled?

Sulfates from atmosphere —> deposited in the soil where bacteria converta sulfates into different forms

When plants die sulfur compounds return into the atmosphere — released as hydrogen sulfide

How is sulfur slowly cycled?

Sulfer (S₈) - stored in sediments (gypsum) and fossil fuel reserves

Released by weathering, hot springs, volcanic activity, or burning fossil fuels.

What is Acid deposition?

When precipiation becomes acidified —> Burning of fossil fuels release Sulfer dioxide (SO₂) —> reacts with oxygen and water —> sulfurous acid (H₃SO₃) and sulfuric acid (H₂SO₄)

Lowers pH of soil and aquatic systems —> sever impacts on ecosystems and affects human-made enviornment by degrading buildings and monuments

How is Nitrogen important?

Necessary to make proteins (amino acids) and DNA

78% of nitrogen gas makes up the atmosphere — but uselss to organisms —> must be converted first

Can be absorbed by plants and consumed by hetertrops. — Excess nitrogen is realsed as waste

What is Nitrogen Fixation

Process of converting nitrogen gass into usbale forms done by:

Lightning - Has enough energy to break the bonds between N₂, and can convert it into other forms

Ntrogen-fixing bacteria - located in soil, water, and/or root nodules legumes; converts nitrogen gas —> ammonia (NH₃⁺) + water —> ammonium (NH₄⁺) which can be used by plants

Nitrifying bacteria - Performs nitrification —> conversion of ammonia —> nitrite (NO₂^-) and nitrate (NO₃^-) ions. even easier for plants to use

What is ammonification?

When decomposes realse nitrogen during the breakdown of waste and tissues of dead organisms

Ammonium or ammonia is produced and added into the environment

What is denitrifiaction?

When denitrifiying bacteria take organic nitrogen compounds (nitrite and nitrate) and turn it back inot nitrogen gas

Occurs in enviornments with very little oxygen available.

How is phosphorus important?

Key element in life - present in cell membranes (phosphilipid bilayer), ATP, and in bones and teeth

only one thst DOES NOT cycle in the atmosphere; Consumers can obtain it by eating foods like milk, grains, or meats.

Producers requrire it in the form of phosphates (PO₄^3-)

How is phosphorus rapidly cycled?

Invovles living organisms

Wastes/organic matter from living organisms (bones, teeth, cell membranes, ect.) —> broken down by decomposers —> releases phosphates into the soil to be taken by plants

How is phosphorus slowly cycled?

Invovles the lithosphere

Parts of organisms that haven’t fully decomposed become part of layers of sediment at the bottom of the ocean. Becoming trapped for a long time

Phosphate ions are soluble in water, can be dissolved out of rock and absorbed plants

Phosphates reoded from rock can be carried from land to oceans —> absorbed by algae and enter the food chain

What is Eutrophication?

The build-up of excess nutrients in aquatic systems

The nutrients can leach into nearby water bodies, and promote uncontrolled growth of aquatic producers

What is productivity?

rate at which an ecosystem’s producers capture and store energy within organic compounds over a certain length of time

Can be measured in energy per are, per year (J/m²/a) or biomass of vegetation added to an ecosystem per area, per year (g/m²/a)

What factors can affect the productivity of an ecosystem?

Number of producers present

Amount of light and heat available

Amount of rainfall the system recieves

What is the Gaia Hypothesis?

How the biosphere acts like an organsism that maintains its enviornmental conditions within certain limits

What are stromatolites? How are they useful?

Piled up cells of dead micro-organisms that trap or precipitate sedminets that are found in sedimentary rocks.

Helped learn about oxygen levels in early life and about photosynthetic organisms