Review on ecosystems and source of energy
What is an ecosystem?
An ecosystem is all the living organisms in a given area as well as the abiotic factors with which they interact.
What are the benefits of photosynthesis?
It gives us oxygen, provides food for the organisms on Earth, and removes carbon dioxide from the atmosphere.
What is an ecological pyramid?
Ecological pyramid: A diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or a food web.
What is “biomass”?
Biomass is a term that is used to describe the amount of organic material in an ecosystem. Producers add biomass to an ecosystem by making organic compounds.
Describe the second trophic level.
The second trophic level is occupied by the herbivores that feed on the producers. These organisms are referred to as primary consumers.
In an ecosystem, what is the ultimate source of energy?
The sun.
Many organisms on Earth do not have the capability to use the sun’s energy directly. What do these organisms do?
The organisms on Earth that cannot carry out photosynthesis rely on the energy that has been stored in the organic compound glucose (a type of sugar) as their source of energy.
What two factors are most important in determining net primary productivity in aquatic ecosystems?
In aquatic ecosystems, productivity is limited by two factors:
a) light
b) the availability of nutrients.
Define: Gross Primary Productivity
Gross primary productivity is the rate at which the producers (autotrophs) in an ecosystem capture energy.
Gross primary productivity is the amount of light energy that is converted to chemical energy by photosynthesis per unit time.
Describe the first trophic level.
The first trophic level in a food chain is always made up of producers. These organisms are referred to as primary producers.
How much of the sun’s energy is used by the living organisms on Earth?
It is less than 1% is actually used by living organisms.
What are autotrophs?
Autotrophs are organisms that have the ability to use energy from the sun to convert simple inorganic substances into complex organic substances. Autotrophs convert carbon dioxide and water into carbohydrates (glucose).
What three factors are most important in determining net primary productivity in terrestrial ecosystems?
In terrestrial ecosystems, three factors determine the net primary productivity:
a) light
b) temperature
c) amount of rainfall
In what two ways can the productivity of an ecosystem be measured?
The productivity of the ecosystem can be measured in two ways:
1. Gross primary productivity
2. Net primary productivity
What is a trophic level?
Each step in a food chain is called a trophic level. The trophic level indicates the organism’s position in the sequence of energy transfers.
Which 1% of living organisms are capable of making use of the sun’s energy?
This 1% is used by the organisms that are capable of photosynthesis which are plants.
What organisms on Earth are considered to be autotrophs?
The only organisms that are autotrophs are the green plants, the algae, a few species of bacteria and a few protists.
What is so important about “net primary productivity”?
Net primary productivity is the most important measurement because it represents the amount of chemical energy (glucose) that will be available to consumers in the ecosystem.
What might happen if squid were eliminated from this food web?
Penguins and elephant seals may starve and crabs may over populate.
What is a food web?
Food web: The network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem. A food web links all the food chains in an ecosystem together.
What is the basic definition of “photosynthesis”?
Photosynthesis is the process by which green plants (and a few other organisms) use the light energy from the sun to convert water and carbon dioxide into glucose and oxygen.
What are the main autotrophs on land?
It is green plants.
What is “net primary productivity”?
Net primary productivity is equal to gross primary productivity minus the amount of energy used by the producers for respiration.
What trophic level would be occupied by carnivores feeding upon herbivores?
These organisms are referred to as secondary consumers.
What is the first step in every food chain?
All food chains begin with an autotroph.