Chapter 47: the Biosphere

Chapter 47: The Biosphere

Section 4: Energy and Nutrients: Building the Web of Life

Energy and Nutrients: Building the Web of Life

· One of the most important factors in any ecosystems is the _______________

______________________ through the ecosystem

· Approximately __________ of the energy plants absorb from the sun is used immediately

· The rest is stored in plant tissues in the form of ________________________

· Animals that ______________________________ obtain this energy

· Energy cannot be ____________________, or _______________________

· Thus energy in an ecosystem is referred to as a _____________ rather than a cycle

· ______________________ are generally recycled through an ecosystem

· When an animal dies, its matter does not _____________________

· Rather, it ______________________ and eventually gets used by another organism

The Flow of Energy

· The _____________ is the ultimate source of energy for all living things

· Because photosynthetic organisms are able to make their own food from inorganic substances, they are called __________________________

· Animals, on the other hand, are _________________________

· Consumers get their energy either _________________________________ from producers

· Consumers that feed directly on producers are called ___________________

_____________________________

o __________________________

· Consumers that feed on primary consumers are called ___________________

__________________________

o _________________________

· Energy flows through an ecosystem from the sun to producers and then to consumers

· When plants and animals in an ecosystem die, their remains do not build up because of the presence of ____________________________

· Decomposers are organisms that obtain their energy from ________________

_________________________________

· Each step in this series of organisms eating other organisms is called a __________________, or ____________________ level

· At each higher trophic level, less and less of the energy originally captured by the producers is available

· Approximately ___________ of the energy at one trophic level can be used by animals at the next trophic level

· At each successive trophic level, _________________________ is available to an organism

Ecological Pyramids

· Ecologists use ___________________________________ to represent the energy relationships among trophic levels

· There are three types of ecological pyramids

o _______________________________

o _______________________________

o _______________________________

Pyramid of Energy

· A pyramid of energy shows the total amount of ________________________

_________________ at each successive level

Pyramid of Biomass

· The trophic levels of an ecosystem can also be represented by a pyramid of biomass, which shows the ________________________________________ at each level

Pyramid of Numbers

· Relationships among trophic levels may also be represented by a pyramid of numbers

· A pyramid of numbers illustrates the ________________________________

________________________ at each level

Biogeochemical Cycles

· Although energy moves in a one-way direction through an ecosystem, nutrients are recycled

· All organisms require certain essential nutrients in order to _____________

· As members of each trophic level eat members of the level beneath them, they acquire the complex organic molecules and elements they need in addition to energy

· Nutrients move through the biosphere in a series of physical and biological processes called ________________________________, or nutrient, ________________

The Water Cycle

· The movement of water from the atmosphere to the Earth and back to the atmosphere is called the ______________________________

· The water cycle consists of an alternation of __________________________ and ________________________

· Water molecules enter the air by evaporation from the ocean and other bodies of water

· In the air, water molecules condense and then return to the Earth in the form of _________________________

· On land, most of the rainwater runs along the surface of the ground until it enters a river or stream that carries it to a larger body of water

· Some water sinks into the ground and is called ________________________

· The upper surface of groundwater is known as the ______________________

The Nitrogen Cycle

· All organisms require nitrogen to __________________________________

· The movement of nitrogen through the biosphere is called the _____________________________________

· However, most of the nitrogen cannot be directly used by living things

· It must be _______________________ into other forms

· Certain bacteria that live on roots of plants change free nitrogen in the atmosphere into nitrogen compounds that can be used by living things

o ______________________________________

· Once the nitrogen compounds are available, plants use them to make plant proteins

· Animals then eat the plants and use the proteins to make animal proteins

· When the plants and animals die, the nitrogen compounds ________________

________________________________

· Eventually other bacteria in the soil break down these nitrogen compounds into free nitrogen in a process called _________________________________

· These bacteria are called denitrifying bacteria

· Through the process of denitrification, free nitrogen is returned to the atmosphere

The Carbon and Oxygen Cycles

· The process by which carbon is moved through the environment is called the ______________________________

· During photosynthesis, green plants and algae use carbon dioxide from the atmosphere to form __________________

· Consumers and decomposers use glucose is respiration, during which they produce carbon dioxide

· Carbon dioxide is then released into the atmosphere, completing the carbon cycle

· The movement of oxygen through the environment is called the ________________________________

· During photosynthesis, water molecules are split, releasing oxygen into the atmosphere

· The oxygen is used by most organisms for respiration

· During respiration, ___________________________________

· The water is absorbed by plants, and the cycle begins again

Nutrient Limitation

· The rate at which producers can capture energy and use it to produce living tissue is controlled be several factors, one of which is the amount of ___________________________________

· If a nutrient is in short supply – thus limiting an organism’s growth – it is called a _________________________________

Feeding Relationships

· The simplest feeding relationship is a _______________________________

· In one food chain, a big fish eats little fish that eat tiny fish that eat plankton

· Nature is almost never that simple

· Instead of using a food chain, which only shows one feeding level, ecologists use ___________________________

· Food webs have many ___________________________________