1 Chemical/Nutrient Recycling in Ecosystems

DO Now 1.In addition to energy, what do organisms need to survive?

Anything that has mass and takes up space Matter is recycled in ecosystems What is matter composed of? Matter

Levels of organization in the biosphere

Elements in Living Things The elements found in significant amounts in organisms are –Carbon –Hydrogen –Oxygen –Nitrogen –“HONC” HONC if you love science! Also phosphorus and sulfur “HONC-PS”

Law of Conservation of Mass Matter is neither created nor destroyed! So what happens when matter seems to just “appear” or “disappear”?

What happens to matter in the biosphere? Matter is recycled by naturally occurring chemical reactions!

What four elements primarily make up living organisms? Hydrogen, Oxygen, Nitrogen, Carbon These elements (along with others such as _sulfur__ and _phosphorus_ are the basis of life’s most important compounds: water, carbohydrates, lipids, nucleic acids and proteins What four elements primarily make up living organisms? Hydrogen, Oxygen, Nitrogen, Carbon These elements (along with others such as _sulfur__ and _phosphorus_ are the basis of life’s most important compounds: water, carbohydrates, lipids, nucleic acids and proteins 9

CYCLES OF MATTER In other words, a handful of elements combine to form the building blocks of all known organisms. However, organisms cannot manufacture these elements and do not “use them up”. Where these essential elements come from? In other words, a handful of elements combine to form the building blocks of all known organisms. However, organisms cannot manufacture these elements and do not “use them up”. Where these essential elements come from?

CYCLES OF MATTER Unlike the one-way flow of energy, matter is recycled within and between ecosystems

BIOGEOCHEMICAL CYCLE Process in which elements, matter is passed from one organism to another. As matter moves through these cycles, it is transformed which means that it is never created or destroyed, just changed. Process in which elements, matter is passed from one organism to another. As matter moves through these cycles, it is transformed which means that it is never created or destroyed, just changed.

The Water Cycle

14 The Carbon and Oxygen Cycles The pathway of carbon and oxygen through an ecosystem

The Carbon and Oxygen Cycles 1. Almost all oxygen in Earth’s atmosphere originally came from the photosynthetic activities of plants 2. How do C and O cycle through the biosphere? 2 processes – PHOTOSYNTHESIS AND CELLULAR RESPIRATION

The Carbon and Oxygen Cycles

Carbon Cycle How have humans affected the carbon cycle? What processes are putting too much carbon dioxide into the atmosphere? What problem does this lead to? How have humans affected the carbon cycle? What processes are putting too much carbon dioxide into the atmosphere? What problem does this lead to? 17

18 The Nitrogen Cycle The pathway of nitrogen through an ecosystem

Nitrogen is an important element in living things Used to make proteins and nucleic acids! Nitrogen gas (N 2 ) makes up 78% of the earth’s atmosphere However…most organisms cannot use N 2 directly Why can’t organisms use N 2 directly?

How do plants get nitrogen? Rely on Nitrogen Fixing Bacteria! These bacteria live in the roots of some plants (legumes – peas, peanuts, beans) and in the soil These nitrogen fixing bacteria are the only organisms that can “fix” atmospheric nitrogen into a usable form (ammonia) Rely on Nitrogen Fixing Bacteria! These bacteria live in the roots of some plants (legumes – peas, peanuts, beans) and in the soil These nitrogen fixing bacteria are the only organisms that can “fix” atmospheric nitrogen into a usable form (ammonia) 20

Plants and Nitrogen Compounds So, nitrogen is obtained by plants either directly from the bacteria in their roots, or in the soil Some nitrogen in the soil also comes from decaying matter – decomposers break down waste and dead organisms into usable forms of nitrogen

What are the usable forms of nitrogen? Most plants use nitrogen in two inorganic forms to make proteins –NH 3 (ammonia) and NO 3 - (nitrate) Most plants use nitrogen in two inorganic forms to make proteins –NH 3 (ammonia) and NO 3 - (nitrate) 22

Animals must eat plants to meet their nitrogen needs So, what organisms are absolutely necessary for the nitrogen cycle to continue? –BACTERIA!!

How does nitrogen get back into the atmosphere? Other bacteria convert nitrates back into nitrogen gas. This process is called DENITRIFICATION.

Atmospheric nitrogen fixation – a relatively small amount of nitrogen gas is converted into usable forms by lightning 25

The Nitrogen Cycle

The Phosphorus Cycle Movement of phosphorus from environment to organisms and back to environment P is needed to form bones and teeth in animals P is needed to form nucleic acids Movement of phosphorus from environment to organisms and back to environment P is needed to form bones and teeth in animals P is needed to form nucleic acids 27

How do plans and animals get phosphorus? Plants get it from soil and water Animals get it by eating plants or other animals that have eaten plants Slow cycle, does not usually involve atmosphere Plants get it from soil and water Animals get it by eating plants or other animals that have eaten plants Slow cycle, does not usually involve atmosphere 28

How does P enter soil? When rocks erode, a little P dissolves as phosphates in soil and water P added to soil and water when excess p is excreted in waste from organisms and when organisms die and decompose When rocks erode, a little P dissolves as phosphates in soil and water P added to soil and water when excess p is excreted in waste from organisms and when organisms die and decompose 29

How do plants and animals get phosphorus? Plants absorb phosphates in the soil through their roots Animals eat plants Some p washes off land and ends up in oceans Many phosphate salts not soluble in water, so they sink to bottom of ocean and accumulate as sediment Plants absorb phosphates in the soil through their roots Animals eat plants Some p washes off land and ends up in oceans Many phosphate salts not soluble in water, so they sink to bottom of ocean and accumulate as sediment 30

How do humans affect phosphorus and nitrogen cycles? Fertilizer use! 31