Plants play a crucial role in the carbon cycle because they

a. do not release carbon dioxide during cellular respiration.

b. allow carbon to enter an ecosystem through photosynthesis.

c. have special bacteria that live in their root systems.

d. are chemically converted into fossil fuels when burned.

Which item is a carbon sink and not part of the

carbon cycle?

a. carbon in the atmosphere in the form of

carbon dioxide

b. consumers breaking down carbohydrates into

carbon dioxide during respiration

c. carbon found within limestone rocks

d. carbon dioxide being converted into

carbohydrates during photosynthesis

Which of the following is not a true

statement about cellular respiration?

a. It is essentially photosynthesis in

reverse.

b. Oxygen is one of the primary

reactants.

c. It produces energy for organisms to

use.

d. Sugar molecules are its primary

products.

We use but don’t always reuse.

We recycle paper, metals, water, etc.

We recycle almost 50% of paper

in U.S. – about 42 million tons.

But ecosystems constantly re-use

carbon, nitrogen and phosphorus.

All life is based on the element CARBON.

Carbon is the major chemical

constituent of most organic matter,

from fossil fuels to the complex

molecules (DNA and RNA) that

control genetic reproduction in

organisms.

Carbon Cycle

Carbon is found in protein, fats, and sugars/carbohydrates.

Carbon cycles between the atmosphere, land, water, and

organisms.

Carbon is stored on our planet in the

following major sinks:

(1) as organic molecules in living and dead organisms found in

the biosphere;

(2) as the gas carbon dioxide in the atmosphere;

(3) as organic matter in soils;

(4) in the lithosphere as fossil fuels and sedimentary rock

deposits such as limestone, dolomite and chalk; and

(5) in the oceans as dissolved atmospheric carbon dioxide and as

calcium carbonate shells in marine organisms.

Carbon Cycle

Short-term carbon cycle

Like most everything it starts with producers:

Plants produce carbohydrates (glucose) by photosynthesis.

Consumers eat the plants.

Consumers break down glucose by cellular respiration.

Energy is released back into the atmosphere.

Carbon is released from ecosystems as carbon dioxide gas

by the process of respiration.

Respiration takes place in both plants and animals and

involves the breakdown of carbon-based organic molecules

into carbon dioxide gas and some other compound by

products.

The detritus food chain contains a number of organisms

whose primary ecological role is the decomposition of

organic matter into its abiotic components.

Short-term carbon cycle

Long-term Carbon Cycle cont…

Unused carbohydrates are stored as fat and oil.

Carbon returns to the soil after organism’s death.

Over time this turns into coal, oil, natural gas.

Fossil fuels

How Humans Affect the Carbon

Cycle http://www.youtube.com/watch?v=c40jebr9jbg

Burning fossil fuels releases 6 billion tons CO2 into the

atmosphere.

Trees can remove CO2 from the atmosphere.

This can contribute to global warming.

Long-term Carbon Cycle

When consumers eat, some carbon is stored.

carbonates = bones and shells

Over millions of years carbonates turn into limestone.

largest reservoir/storage of carbon

How Humans Affect the

Carbon Cycle

Since the Industrial Revolution, humans have increased the

quantity of carbon dioxide found in the Earth's atmosphere

and oceans by over 30%.

Major sources of this gas due to human activities include

fossil fuel combustion and deforestation and habitat

destruction.

Emissions from fossil fuels account for about 65% of the

additional carbon dioxide currently found in the Earth's

atmosphere. The other 35% is derived from deforestation and

the conversion of natural ecosystems into agricultural

systems.

Which item is a carbon sink and not part of the

carbon cycle?

a. carbon in the atmosphere in the form of

carbon dioxide

b. consumers breaking down carbohydrates into

carbon dioxide during respiration

c. carbon found within limestone rocks

d. carbon dioxide being converted into

carbohydrates during photosynthesis

The Nitrogen Cycle

Organisms need nitrogen to build proteins that are needed

to build cells.

Nitrogen makes up 78% of the atmosphere (about one

million times more than the total nitrogen contained in

living organisms), but most organisms cannot use it in this

form.

Other major stores of nitrogen include organic matter in

soil and the oceans. In most ecosystems nitrogen is

primarily stored in living and dead organic matter.

Nitrogen Cycle cont…

Nitrogen is cycled between the atmosphere, bacteria, and other organisms.

Bacteria live in the roots of legumes (beans, peas, and clover) in nodules. In exchange for some nitrogen, the bacteria receive carbohydrates from the plants.

Some bacteria live in the soil and put nitrogen in the soil.

Plants use nitrogen in soil, consumers eat plants, and so on…

The Nitrogen Cycle

The Nitrogen Cycle

Almost all of the nitrogen found in any terrestrial ecosystem

originally came from the atmosphere. Significant amounts enter

the soil in rainfall or through the effects of lightning.

The majority is biochemically fixed within the soil by

specialized micro-organisms like bacteria, actinomycetes, and

cyanobacteria.

The Nitrogen Cycle

Decomposers in the Nitrogen Cycle

After bacteria convert nitrogen, plants use the nitrogen and

consumers eat plants.

Decomposers help return nitrogen back to the atmosphere

by breaking down urine, dung, leaves, dead plants and

animals.

Phosphorus Cycle

Needed for bone and teeth formation

Plants get phosphorus from soil and water;

consumers get phosphorus from plants.

Moves from environment to organism to

environment;

usually not in the atmosphere.

The Phosphorus Cycle

Phosphorus Cycle cont…

Phosphorus enters the soil when rock erodes.

Returns through waste and decomposing organisms.

Some phosphates get washed out to the ocean and deposit

on the ocean floor.

Fertilizers

Contain phosphorus and nitrogen

Application of fertilizers to crops has caused increased rates of

nitrate leaching into groundwater. Additional nitrogen entering

the groundwater system eventually flows into streams, rivers,

lakes, and estuaries. In these systems, the added nitrogen can

lead to eutrophication.

Algae blooms

Last Problem

When coal, wood, or oil are burned, nitric oxide is

released.

Nitric oxide combines with oxygen and water vapor to

make nitric acid/acid rain.