Geochemical Cycles Lesson

Biogeochemical Cycles

Bio = Life

Geo = Land

Chemical

Multiple Choice

Review Question: Which statement best describes the movement of matter and energy in an ecosystem?

• Energy recycles and matter recycles.

• Energy recycles and matter flows in one direction.

• Energy flows in one direction, nutrients recycle.

• None of the above.

Multiple Choice

What is the major energy source for our planet?

• Sun

• Moon

• Photosynthesis

The Water Cycle

The water cycle describes 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. The water falling on land collects in rivers and lakes, and much of it flows back into the oceans, where it will once more evaporate.

Multiple Choice

Water exists as liquid over a wide range of temperatures.

• True

• False

Multiple Choice

It takes a small amount of energy for water to evaporate.

• True

• False

Multiple Choice

Water is an example of an abiotic factor that is important to the survival of any ecosystem.

• True

• False

Open Ended

Name two ways humans alter the water cycle and how it effects us.

The Carbon Cycle

Carbon Cycle Described

Carbon is a building block of life, necessary for the macromolecules that make living things. Carbon helps to regulate the Earth’s temperature, makes all life possible, is a key ingredient in the food that sustains us, and provides a major source of the energy to fuel living things. The carbon cycle describes the process in which carbon atoms continually travel from the atmosphere to the Earth and then back into the atmosphere. On Earth, most carbon is stored in rocks and sediments, while the rest is located in the ocean, atmosphere, and in living organisms.

Multiple Select

Which of the following is a reason living things need carbon? Check ALL that apply.

• to make macromolecules

• to provide us with energy

• to regulate Earth's temperature

Multiple Select

According to the diagram, what are three sources of atmospheric carbon?

• Coal

• Natural Gas

• Fossil Fuels

• Sediment

Multiple Choice

According to the diagram, deforestation causes which of the following:

• Uptake of excess carbon

• Release of excess carbon

• It doesn't effect the amount of carbon in the atmosphere.

Multiple Choice

Carbon emissions have steadily risen since 1850.

• True

• False

THE NITROGEN CYCLE

Nitrogen first has to be fixed into a usable compound by bacteria or lightning by a process called nitrogen fixation, then it moves through the food chain and then gets turned back into a gas through denitrification to go back into the atmosphere and start the cycle again.

The Nitrogen Cycle Describe

Nitrogen, the most abundant element in our atmosphere, is crucial to life. Nitrogen is found in soils and plants, in the water we drink, and in the air we breathe. It is also essential to life: a key building block of DNA, which determines our genetics, is essential to plant growth, and therefore necessary for the food we grow. But as with everything, balance is key: too little nitrogen and plants cannot thrive, leading to low crop yields; but too much nitrogen can be toxic to plants, and can also harm our environment. Plants that do not have enough nitrogen become yellowish and do not grow well and can have smaller flowers and fruits. Farmers can add nitrogen fertilizer to produce better crops, but too much can hurt plants and animals, and pollute our aquatic systems, or cause the overgrowth of algae called eutrophication.

Multiple Choice

Nitrogen is a building block of DNA.

• True

• False

Multiple Choice

Too much nitrogen can be toxic to plants.

• True

• False

Multiple Choice

Which process converts atmospheric gaseous nitrogen into a usable compound for plants?

• Denitrification

• Legumes

• Nitrogen Fixation

• Eutrophication

Multiple Choice

Which process returns nitrogen to the atmosphere as a gas?

• Fixation

• Denitrication

• Eutrophication

• Legumes

Multiple Choice

A green body of water due to algae overgrowth, which can occur due to too many nitrates or phosphates. What is this process called?

• Eutrophication

• Legumes

• Denitrification

The Phosphorous Cycle

Necessary nutrient for living things

The Phosphorous Cycle

Phosphorus is a chemical element found on Earth in numerous compound forms. The quantities of phosphorus in soil are generally small, and this often limits plant growth. That is why people often apply phosphate fertilizers on farmland. Animals absorb phosphates by eating plants or plant-eating animals. Phosphorus moves in a cycle through rocks, water, soil and sediments and organisms. Over time, rain and weathering cause rocks to release phosphate ions and other minerals. Plants take up inorganic phosphate from the soil. The plants may then be consumed by animals. Living things then convert it into organic molecules, like DNA. When the plant or animal dies, it decays, and the organic phosphate is returned to the soil.

Multiple Choice

Much of our phosphorous is stored in:

• the air

• rocks

• clouds

Multiple Choice

Phosphorous is the least important compound in these cycles, as living things do not need it.

• True

• False

Multiple Choice

How do we get the phosphorous that we need to survive?

• from the air we breathe

• through the food chain

• through the water we drink.

Multiple Choice

Which of the following are ways that humans impact the phosphorous cycle?

• Deforestation

• Excess Fertilizers

• Both of these

The Sulfur Cycle

Living things need sulfur to make their macromolecules.

The Sulfur Cycle

Sulfur is an essential element for the macromolecules of living things. On land, sulfur is deposited in four major ways: precipitation, direct fallout from the atmosphere, rock weathering, and geothermal vents. Some ecosystems rely on chemoautotrophs using sulfur as a biological energy source. Human activities have played a major role in altering the balance of the global sulfur cycle. The burning of large quantities of fossil fuels, especially from coal, releases larger amounts of hydrogen sulfide gas into the atmosphere. As rain falls through this gas, it creates the phenomenon known as acid rain.

Multiple Choice

Sulfur is used by chemotrophs to create carbohydrates.

• True

• False

Multiple Choice

What major phenomenon is a result of human activity overproducing sulfur emissions?

• Eutrophication

• Acid Rain

• Tornadoes

Open Ended

Does life on Earth control these life sustaining processes or does life just influence these processes? Support your opinion.