Ap Bio 1.2 Chemistry on a Global Scale

Biogeochemical Cycles

Is the movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth’s crusts.

Water Cycle

how water evaporates from the surface of the earth, rises into the atmosphere, cools and condenses into rain or snow in clouds, and falls again to the surface as precipitation.

Nutrient Cycles

3 cycles of nutrients: Carbon, Nitrogen, and phosphorus

Importance of Nutrient Cycle

Every organism needs nutrients to build tissues and carry out life functions. Nutrients pass through organism and the environment through biogeochemical cycles.

Carbon Cycle

Carbon is a key ingredient of all organic compounds. Processes involved in the carbon cycle include photosynthesis and human activities such as burning.

Nitrogen Cycle

Nitrogen is needed by all organisms to build proteins. Processes involved in the nitrogen cycle include nitrogen fixation and denitrification.

Nitrogen Fixation

Certain bacteria convert nitrogen gas into ammonia.

Denitrification

Soil bacteria convert nitrogen compounds called nitrates back into nitrogen gas

Phosphorus Cycle

Phosphorus is needed for fertilizer. Most of the phosphorus is in rocks and oceans sediments. Stored phosphorus is released into water an soil where it is used by organisms.

Decomposer

Decomposers and detritivores plat a key role in the general pattern of chemical cycling.

Detritivores

Animals eat on dead organic material

Vegetation

plant life or total plant cover (as of an area)

The Hubbard Brook Experiment Forest

Research team constructed a dam on the site to monitor loss of water and minerals

• Sprayed herbicides

• Deforestation leads to lots of loss of nutrients and mineral that lead to rivers.

• Causes nitrate to increase in water sources

Human population disturbs chemical cycles

Humans have added new materials, some of them toxins, to ecosystem

Agriculture and Nitrogen Cycling

Nitrogen is the main nutrient lost through agriculture; greatly impacting the nitrogen cycle

Contamination of Aquatic Ecosystems

The critical load for a nutrient is the amount that plants can absorb without damaging the ecosystem

• excess nutrients are added to an ecosystem and the remaining nutrients can contaminate groundwater freshwater and marine ecosystems

• Sewage runoff causes cultural eutrophication and excessive algal growth that harms the freshwater ecosystem

Eutrophication

excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen.

Acid Precipitation

Combustion of fossil fuels is the main cause of acid precipitation (factories)

Toxins in the Environment

• One reason toxins are harmful is that they become more concentrated in successive trophic levels

• In biological magnification, toxins concentrate at higher trophic levels, where biomass is lower

Isotopes

Two atoms of an element that differ in number of neutrons

Radioactive Isotopes

Decay spontaneously, giving off particle and energy