Science Unit Test Community Interactions and Biogeochemical Cycles

Carbon is a major component of all organic compounds, including carbohydrates, lipids, proteins, and nucleic acids. Carbon dioxide is continually exchanged between the atmosphere and oceans. What geological process returns carbon to the atmosphere in the form of carbon dioxide?

Volcanic activity

Phosphorous Cycle

A cycle that remains on land and does not go into the atmosphere.

Energy Pyramid

A model of energy flow in a community.

Energy from food must be transformed into the bonds of _________ before it can be used by cells.

ATP

How do human beings contribute to the phosphorus and sulfur cycles?

Adding chemical fertilizers to the soil

Interdependence

All living things are dependent on both nature and each other for survival.

Ecosystem

All the living and nonliving factors that interact within a specific region.

Keystone Species

An organism that helps define an entire ecosystem. Without it, the ecosystem would change drastically or cease to exist.

Invasive Species

An organism that isn't native to the area, They cause great economic and environmental harm to the new area.

In the carbon cycle, carbon is transferred from animals to decomposers in all of the following ways EXCEPT

As carbon dioxide.Bacteria use larger carbon containing biomolecules, such as fats, proteins, and carbohydrates. Carbon dioxide goes back into the atmosphere, or is used by plants.

Sulfur and phosphorus compounds enter bodies of water, such as ponds, lakes, and rivers

As run-off containing fertilizers and detergents.

Soil bacteria are responsible for carrying many steps in the nitrogen cycle. Soil bacteria are NOT responsible for

Assimilation. Assimilation is the incorporation of nitrogen into proteins and DNA. All organisms do this. Only bacteria can do the other steps.

Each autumn, the forest floor is covered by leaves that have fallen from trees. Which type of organism is MOST effective in decomposing the leaf tissue, allowing the nutrients and minerals to be recycled in the environment?

Bacteria break down and decompose dead organic matter, allowing the nutrients and minerals to be recycled and reused by other living things.[

All of the statements about the nitrogen cycle are true EXCEPT one. That is

Bacteria located in the soil trap excess nitrogen and help to remove it from plant roots. The opposite situation is true. Bacteria help ADD nitrogen to the soil and to plant roots.

____________ is the dry weight of tissue and other organic matter in an ecosystem.

Biomass

The burning of fossil fuels by cars and factories has most affected the ______________ cycle.

Carbon

The process of respiration is essential in the oxygen/carbon dioxide cycle. Respiration removes ______ from the atmosphere and produces and releases ______ to the atmosphere.

Carbon dioxide, oxygen

Phosphorus is an essential nutrient for plants and animals. Phosphorus normally occurs in nature as part of a phosphate ion (PO4)3. As you can see from the diagram of the phosphorus cycle, phosphorus is a component of plant fertilizers. Two of the critical roles phosphorus plays in life on Earth is that it is a component of ATP as well as all

Cell membranes

Most organisms break down sugar to produce usable energy through the process of

Cellular respiration

What two processes fuel the carbon cycle?

Cellular respiration and photosynthesis naturally fuel the carbon cycle by using and producing carbon dioxide.

________ are responsible for recycling matter back into the food web once an organism has died.

Decomposers

Ammonification

Decomposition by bacteria resulting in the formation of ammonia.

Nitrogen Cycle

Describes how nitrogen moves between plants, animals, bacteria, the atmosphere, and the soil in the ground.

Humans add greatly to the carbon cycle by

Driving cars

Limiting Factors

Environmental factors that limits the growth and size of a population.

Rivers, springs, and aquifers are all fresh water components of the hydrologic cycle. As this water progresses through the cycle, it will eventually ___________ into the atmosphere before ____________ and falling back to the earth as precipitation.

Evaporate; condensing

Dentrification

Extra nitrogen in the soil gets put back into the air by special bacteria.

The size of a food web is limited by the number of

Primary producers

Which biological molecule contains a large amount of the element nitrogen?

Proteins

Parasitism

Relationship where one organism benefits by harming the other.

Commensalism

Relationship where one species is benefited while the other is unaffected.

Mutualism

Relationship where two species benefit.

In the food web the amount of matter

Remains constant. The location of the matter may change, but its total amount remains constant.

Carbon dioxide is returned to the atmosphere primarily by the

Respiration of consumers. This process takes in oxygen and releases carbon dioxide, a vital component of the carbon cycle.

Consider the aquatic phosphorus cycle. Phosphorus is the limiting nutrient for aquatic organisms. Decomposition naturally returns phosphorus to the aquatic cycle, but phosphates from fertilizers, sewage and detergents can cause pollution in lakes and streams. Over-enrichment of phosphate in freshwater can lead to __________ which, when they die and decay, leads to _____________.

algal blooms; eutrophication

Nitrogen in the atmosphere must be "fixed" before it can be used by plants. Atmospheric nitrogen is "fixed" by

bacteria and lightning Nitrogen is fixed or chemically combined with other elements to form a usable chemical compound. Plants are then able to use nitrogen in this form; they are not able to use it in its atmospheric form.

Consider the aquatic phosphorus cycle. On land most phosphorus is found in rocks and minerals. In the oceans, phosphorus is deposited from decomposition, excretion from animals, run-off from the land, and finally ______________ of rocks and minerals.

weathering

In an ecosystem, some plants may convert atmospheric nitrogen into ammonia through a process called

Nitrogen fixation

Plants need nitrogen in order to survive. The problem is they cannot take in the atmospheric nitrogen, but instead must rely on a certain class of bacteria that are able to turn atmospheric nitrogen into other nitrogen compounds, such as ammonia and nitrates. What is the name of this process?

Nitrogen fixation is the process of taking N2 and turning it into ammonia and other nitrate forms soils so plants can absorb the nitrogen through their roots.

Abiotic Factors

Nonlivng things in an ecosystem; water, rocks, sunlight, soil.

Decomposers

Organisms that breaks down dead things returning them back to the environment. Bacteria, fungi.

Consumers

Organisms that cannot make their own food.

Omnivores

Organisms that eat both meat and plants.

Detritivores

Organisms that eat dead matter. Earthworms, vultures.

Primary Consumers

Organisms that eat producers. Deer, turtles, and birds.

Secondary Consumers

Organisms that eat the herbivores.

Producers

Organisms that make their own food.

Carnivores

Organisms that only eat meat.

Herbivores

Organisms that only eat plants.

CO2 is returned to the atmosphere by all methods EXCEPT

Photosynthesis

Water that has evaporated returns to the earth as

Precipitation

Biotic Factors

Living things in an ecosystem; plants, animals, and bacteria.

All living things use nitrogen to

Make proteins

Carbon Cycle

The continuous movement of carbon from the nonliving environment into living things and back, through cellular respiration and photosynthesis.

The diagram shown above, illustrates the _______ cycle.

The diagram illustrates the carbon cycle. Remember, matter is conserved; neither created or destroyed. Carbon dioxide in the air is used by plants and other producers to produce glucose, the energy molecule for all life. Carbon dioxide is put back into the air through respiration as well as combustion reactions.

Symbiotic Relationships

The ecological relationship between two species that depend on each other for survival.

Nitrogen Fixation

The first step of making nitrogen usable by plants. Bacteria change nitrogen into ammonium.

Carrying Capacity

The number of individuals that can be supported by the resources of the environment

Water Cycle

The process by which water moves back and forth between the Earth's surface and the atmosphere.

Nitrification

The process where ammonium gets changed into nitrates by bacteria. Plants can absorb nitrates.

Niche

The role and position a species has in its environment.

Lithosphere

The solid part of the Earth AKA the ground.

Assimilation

This is how plants get nitrogen. They absorb nitrates from the soil into their roots. Then the nitrogen gets used in amino acids, nucleic acids, and chlorophyll.

According to the law of conservation of matter, matter is never created or destroyed. It only changes form as is evident in the water cycle. But what about the other geochemical cycles? Nutrients circulate throughout the environment in complex cycles called biogeochemical cycles, or nutrient cycles. Carbon, oxygen, phosphorus, and nitrogen are nutrients that cycle through all of Earth's spheres and organisms.

planting cover crops