Biogeochemical Cycle
The Water Cycle
1. Name three important needs for water.
 Biological Mechanisms
 Habitats for animals, plants, and microorganisms
 Cycles all the material used by living things
2. How is water distributed through the biosphere?
Water is distributed through the biosphere through in a cycled called the water cycle.
3. What draws water back to the earth?
Gravity draws back water to the earth.
4. What is transpiration?
Transpiration is the process of water evaporating from the leaves of plants.
5. What determines which plants to grow where?
The amount of precipitation in an area determines where a plant grows.
6. What is an aquifer?
An aquifer is the water-saturated zone of soil and rock.
7. Name two ways water travels from land to enter the ocean.
 Seeps from the aquifer
 Runoff from the surface
8. What does runoff include?
Runoffs include flows from river, melting snowfields, and melting glaciers.
9. How much water enters the hydrologic cycle?
Over 80% of water enters the hydrologic cycle.
10. How much water falls back as rain?
52% of the 80% of water falls back as rain.
The Carbon Cycle
1. What are macronutrients? Micronutrients?
Macronutrients are nutrients that are used by organisms in large quantities, whereas,
microorganisms are used by organisms in trace quantities.
2. What is the role of each of the following in the carbon cycle? State an example of each.
a. Primary producers- takes in carbon in carbon dioxide and fix it in organic compounds;
releases carbon dioxide into the atmosphere during respiration.
b. Secondary producers- during plant consumption, carbon is passed from producers into
primary consumers; releases carbon into the atmosphere during respiration
c. Decomposers- breaks down organic matter of plants animals; releases carbon dioxide
into the atmosphere during respiration
3. Where is most of the Earth's carbon located and in what form?
Most of the earth’s carbon is located in the atmosphere, in the form carbon dioxide.
4. How does carbon enter the biotic part of the ecosystem?
Carbon enters the biotic part of the ecosystem through photosynthesis.
5. What function do plants have in the forest in the carbon cycle?
The role of forest plants in the carbon cycle is to take the carbon in carbon dioxide and fix it in
organic compounds.
6. How is carbon dioxide returned to the atmosphere?
Carbon dioxide is returned to the atmosphere by through respiration in plants, consumers,
and detritus feeders. Also, combustion of fossil fuels and burning of wood and plants allows
carbon to the atmosphere.
7. What is a primary producer?
A primary producer is a plant that is able to convert carbon dioxide and water into oxygen
and glucose by using light or chemical energy.
8. What happens when primary and secondary consumers die?
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?
To contribute to the carbon cycle, detritus feeders break down the organic matter.
10. What is a fossil fuel?
A fossil fuel is carbon-containing organic matter converted into coal, gas, and natural gas.
11. How does carbon get in the ocean?
Carbon is dissolved into the ocean.
The Nitrogen Cycle
1. What percent of the air is nitrogen?
Approximately 78% of the air is nitrogen.
2. Why is nitrogen essential to life?
Nitrogen is essential to life because it is a key component in amino acids and nucleic acids.
3. How do plants and animals get nitrogen if not from the atmosphere?
Plants and animals receive nitrogen through the process of nitrogen fixation.
4. What are nitrogen fixing bacteria?
Nitrogen fixing bacteria are bacteria that convert nitrogen in the soil to ammonia.
5. What is a major reservoir for ammonia?
A major reservoir for ammonia is soil.
6. Why do herbivores need nitrogen?
Herbivores need nitrogen in order to synthesize key organic compounds.
7. What is denitrification?
Denitrification is the process of microscopic bacteria, fungi, and other organisms breaking
down the nitrates in the soil, allowing nitrogen to be released into the atmosphere.
The Phosphorus Cycle
1. Why is phosphorus an important biological molecule?
Phosphorus is an important biological molecule because it is a component in ATP and the
coenzyme NADP.
2. What happens to phosphorus that erodes from rock and soil?
When phosphorus is eroded from rock and soil, it is united with oxygen to form phosphate.
3. How are phosphates incorporated into the organic molecules in plants and animals?
Phosphates are incorporated into the organic molecules in plants and animals by synthesizing
organic molecules.
4. What happens to the phosphates when plants and animals die?
When plants and animals die, the phosphorus are returned to the lake.
5. What happens to the phosphorous that is carried by runoff to the oceans?
When phosphorus is carried by runoff into the oceans, they are then concentrated in marine
sediments.
6. How are phosphates incorporated into the organic molecules in aquatic plants and animals?
Phosphorus are incorporated into the organic molecules in aquatic plants and animals by
synthesizing organic compounds.
7. What is different about the phosphorus cycle as compared to the water, carbon, and
nitrogen cycles?
The difference between the phosphorus cycle and the other biogeochemical cycles is that
geologic upthrust must occur.