Download Biogeochemical Cyclesseventh class

Biogeochemical Cycles
Name: __________________
Period: ________
THE WATER CYCLE:
1. Name three important needs for water.
2. How is water distributed through the biosphere?
3. What draws water back to the earth?
4. What is transpiration?
5. What determines which plants grow where?
6. What is an aquifer?
7. Name two ways that water travels from land to enter the ocean.
8. How much water enters the hydrologic cycle?
THE CARBON CYCLE:
1. Where do nutrients come from?
2. What are macronutrients? Micronutrients? Give examples of each.
3. What is the role of each of the following in the carbon cycle? State an example of each.
4. Where is most of the Earth’s carbon located and in what form?
5. How does carbon enter the biotic part of the ecosystem?
6. What function do plants have in the forest in the carbon cycle?
7. How is carbon dioxide returned to the atmosphere?
8. What happens when primary and secondary consumers die?
9. What do detritus feeders contribute to the carbon cycle?
10. How are fossil fuels produced? Give some examples of fossil fuels.
11. What role do fossil fuels play in the carbon cycle?
12. How does carbon enter the ocean?
THE NITROGEN CYCLE
1. What percent of the air is nitrogen?
2. Why is nitrogen essential to life?
3. How do plants and animals get nitrogen if not from the atmosphere?
4. Explain the role of legumes and nitrogen fixing bacteria.
5. What is a major reservoir for ammonia?
6. Why do herbivores need nitrogen?
7. What is denitrification?
THE PHOSPHORUS CYCLE
1. Why is phosphorus an important biological molecule?
2. What happens to phosphorus that erodes from rock and soil?
3. How are phosphates incorporated into the organic molecules of plants and animals?
4. What happens to the phosphates when plants and animals die?
5. What happens to the phosphorus that is carried by runoff to the oceans?
6. How are phosphates incorporated into the organic molecules in aquatic plants and animals?
7. What is different about the phosphorus cycle as compared to the water, carbon, and nitrogen cycles?
THE ROCK CYCLE
1. How does igneous rock form?
2. When rocks are affected by weathering and erosion, what type of rock do they turn into?
3. When heat and pressure are applied to a sedimentary rock, what type of rock does it turn into?
4. When magma is cooled, what type of rock does it turn into?
5. How does metamorphosis occur?
Answer Key
Biogeochemical Cycles
THE WATER CYCLE:
1. Name three important needs for water.



Biological mechanisms: Photosynthesis, digestion, cellular respiration
Habitat for many species
Participates in cycling of materials used by living things
2. How is water distributed through the biosphere?

Water or hydrologic cycle - “hydro” = water
3. What draws water back to the earth?

Gravity draws the water back to the earth in the form of rain, sleet and snow
4. What is transpiration?

Evaporation of water through the leaves. Specifically there are openings in the leaves called
“Stomata” where the water evaporates from.
5. What determines which plants grow where?

The amount of precipitation received by the area
6. What is an aquifer?

The water saturated zone of soil and rock. Water enters as it percolates from the surface of the
land to the water table. Water then seeps from the aquifer into the ocean.
7. Name two ways that water travels from land to enter the ocean.


Seepage from the aquifer
Runoff from the surface including flow from rivers as well as melting snowfields and glaciers
8. How much water enters the hydrologic cycle?

Oceans cover about ¾ of the earth’s surface and contain about 97% of its water. Solar radiation
causes the water’s evaporation from the ocean. Over 80% of the water in the atmosphere
enters this way. This is equivalent to a layer that’s 120cm deep and covers the entire surface of
the ocean.
THE CARBON CYCLE:
1. Where do nutrients come from?

The same pool of nutrients has circulated the earth for billions of years
2. What are macronutrients? Micronutrients? Give examples of each.


Macronutrients: used by organisms in large quantities ex. carbon, hydrogen, oxygen, nitrogen
and phosphorus
Micronutrients: used by organisms in trace (very small) quantities ex.iodine, iron, zinc
3. What is the role of each of the following in the carbon cycle? State an example of each.



Primary Producer: incorporate materials into organic compounds (ex. any plant)
Secondary Consumers: consume primary producers (ex. anything that eats a plant)
Decomposers: release materials back into the nonliving environment (ex. bacteria, fungi)
4. Where is most of the Earth’s carbon located and in what form?

In the atmosphere in the form of carbon dioxide
5. How does carbon enter the biotic part of the ecosystem?

Through photosynthesis
6. What function do plants have in the forest in the carbon cycle?

Take in carbon from carbon dioxide through carbon fixation and “fix” the carbon into organic
compounds like glucose, starch and cellulose, and other carbohydrates.
7. How is carbon dioxide returned to the atomosphere?

Respiration in plants and animals returns carbon to the atmosphere.
8. What happens when primary and secondary consumers die?

Their organic matter enters the soil through the process of decay.
9. What do detritus feeders contribute to the carbon cycle?


Break down organic matter from dead primary and secondary consumers. They are small
animals and microorganisms that subsist on decaying matter such as fallen leaves, dead bodies,
and animal waste. Ex. earthworms, mites, insects, and crustaceans.
Respiration in detritus feeders also returns carbon to the atmosphere.
10. How are fossil fuels produced? Give some examples of fossil fuels.

High pressure and temperature transform carbon containing matter into coal, oil, and natural
gas.
11. What role do fossil fuels play in the carbon cycle?

The products of combustion of fossil fuels include carbon dioxide and other carbon compounds
that enter the atmosphere.
12. How does carbon enter the ocean?

Some carbon dioxide from the air dissolves in oceans and combines with calcium to form
calcium carbonate, which is incorporated into the shells of mollusks and other creatures. When
these shells decay, they transform into limestone, which, over time, dissolves as it is exposed to
water. Carbon is released from the limestone and may retune to the atmosphere.
THE NITROGEN CYCLE
1. What percent of the air is nitrogen?

78%
2. Why is nitrogen essential to life?

It is a key component of amino acids (which make proteins), nucleic acids (which make DNA and
RNA), and ATP (the energy source for our bodies)
3. How do plants and animals get nitrogen if not from the atmosphere?

Nitrogen fixation
4. Explain the role of legumes and nitrogen fixing bacteria.

Legumes form a symbiotic relationship with nitrogen fixing bacteria on the roots of plants.
Legumes are plants like clover, peas, alfalfa, and soybeans. The bacteria reside on the root
nodules of these legumes where they convert nitrogen in the soil to ammonia (NH3) (nitrogen
fixation) which can be taken up by the plant.
5. What is a major reservoir for ammonia?

Soil
6. Why do herbivores need nitrogen?

For synthesis of key organic compounds such as amino acids, proteins, and nucleic acids
7. What is denitrification?

A process performed by a variety of microscopic bacteria, fungi, and other organisms. Nitrates
in the soil are broken down by these organisms and nitrogen is released into the atmosphere.
THE PHOSPHORUS CYCLE
1. Why is phosphorus an important biological molecule?

It is a component of ATP and the coenzyme NADP which are used in important cellular processes
such as photosynthesis. Phosphorus is also present in the sugar-phosphate backbone of nucleic
acids, and is an essential element of phospholipids which make up the cell membrane.
2. What happens to phosphorus that erodes from rock and soil?

Erosion occurs as water rushes over rock, dissolving phosphorus and washing it into rivers and
streams. Phosphorus unites with oxygen to form phosphate and enters a major body of water
like a lake.
3. How are phosphates incorporated into the organic molecules of plants and animals?

Plants in the water are able to absorb the phosphate from the water to use in the synthesis of
organic molecules. Some of the phosphates also enter the soil along the margins of the lake.
Dissolved phosphate is readily absorbed by the roots of plants and then incorporated into
organic molecules. The animal receives the phosphorus when it eats the plant.
4. What happens to the phosphates when plants and animals die?

Phosphates are returned to the lake when the plants and animals die. Plant waste and animal
waste return phosphorus to the water. Once again it may be reabsorbed by plants that line the
lake, and it enters the cycle again.
5. What happens to the phosphorus that is carried by runoff to the oceans?

The phosphorus exists in the form of phosphate in the runoff. Much of the phosphate
concentrates in marine sediment.
6. How are phosphates incorporated into the organic molecules in aquatic plants and animals?

Primary producers in the ocean incorporate phosphates into organic compounds. These
primary producers are eaten by fish and other invertebrates.
7. What is different about the phosphorus cycle as compared to the water, carbon, and nitrogen cycles?

Unlike water, carbon and nitrogen, phosphorus is not found in the gas state in the atmosphere.
THE ROCK CYCLE
1. How does igneous rock form?

Igneous forms when magma cools and makes crystals
2. When rocks are affected by weathering and erosion, what type of rock do they turn into?

Sedimentary rock
3. When heat and pressure are applied to a sedimentary rock, what type of rock does it turn into?

Metamorphic rock
4. When magma is cooled, what type of rock does it turn into?

Igneous rock
5. How does metamorphosis occur?

By heat and pressure