 part of Earth where life exists  located near Earth’s surface where sunlight available  plants need sunlight to produce food - almost every other organism gets its food from plants and algae  needed nutrients must be continually recycled  when an organism dies, body is broken down and nutrients in it become available for use by other organisms  this flow of energy allows life on Earth to continue to exist Biosphere

Nutrient Cycles

The Carbon Cycle

 carbon – an element found in all living things  carbon dioxide (CO 2 ) traps heat in the atm. - greenhouse effect  carbon cycle - same carbon atoms are reused on earth

Plants use CO 2 use CO ₂ from the atm. to make food - photosynthesis carbon becomes part of the plant - food stored as carbohydrates - sugars

Animals eat plants some carbon becomes part of their bodies breathe out C0 ₂ - respiration

Plants and Animals die most of their bodies are decomposed and carbon atoms are returned into air and soil Fossil fuels coal, oil, natural gas takes hundreds of millions of years

Other Paths nonliving things - oceans, rocks, limestone, animal shells and air carbon in rocks released very slowly dissolves into oceans natural combustion - forest and grass fires

Human Impact Burning fossil fuels (combustion) Releases large amount of C0 ₂ in a short time Causes global warming & acid rain Fewer plants - less C0 ₂ removed from atm.

The carbon dioxide enters the atmosphere. The cycle starts over. NASA: Keeping up With Carbon What’s the Deal with Carbon Carbon Cycle Circle of Life

The Carbon Cycle

Atmospheric Carbon Dioxide

Plants use carbon dioxide to make their food (photosynthesis )

Atmospheric Carbon Dioxide Plants use carbon dioxide to make their food (photosynthesis) Green plants are eaten by animals

Atmospheric Carbon Dioxide Plants use carbon dioxide to make their food (photosynthesis) Green plants are eaten by animals respiration

Atmospheric Carbon Dioxide Plants use carbon dioxide to make their food (photosynthesis) green plants are eaten by animals respiration dead remains of plants and animals

Atmospheric Carbon Dioxide Plants use carbon dioxide to make their food (photosynthesis green plants are eaten by animals respiration dead remains of plants and animals decay by fungi and bacteria

N needed for DNA, RNA, and proteins - the building blocks of lifeDNARNAproteins 78% of the Earth’s atm. is nitrogen. Nitrogen (N)

Nitrogen Fixation (N 2 --> NH 3 or NH 4 + ) HOW? Biological or Environmental or Humans BIOLOGICAL: Bacteria (called Nitrogen-fixing bacteria) These bacteria form symbiotic relationships with host plants. The bacteria live in nodules found in the roots of the legume family of plants (e.g. beans, peas, and clover) Nitrogen Fixation N must be altered or “fixed” before living things can use it Nitrogen-fixing bacteria (NFB) NFB live in roots of legumes (beans, peas and clover) releases N into soil other plants get N from soil

Decay decomposers (bacteria, fungi, etc.) – breakdown waste decay of dead things, manure, etc. returns nitrogen to soil and atm.

Human Impact Ocean Dead Zones Rain causes runoff of fertilizer Rapid growth of algae Algae uses up all nutrients Kills aquatic animals and plants nitrogen can also enter the atmosphere to become: Smog Greenhouse gas Acid Rain The Nitrogen Cycle Dead Zones

Denitrifying bacteria Nitrates (NO 3 – ) Detritivores Ammonium (NH 4 + ) Amino acids and proteins in plants and animals Detritus Assimilation by plants Nitrogen-fixing bacteria in soil Nitrogen fixation Decomposition Nitrogen-fixing bacteria in root nodules of legumes Nitrogen fixation Nitrogen (N 2 ) in atmosphere

Phosphorus (P) cycle P necessary for DNA and RNA. Slowest cycle – does not include the atm. Erosion of rocks – enters soil and water Plants – through soil and water Animals – eating plants or other animals Decomposition – returns to soil only

Eutrophication due to excess phosphate in water bodies.