Chapter 13 - Energy And Ecosystem Flashcards
What is the initial source of energy for most organisms?
Sunlight
How is energy passed between organisms?
Biomass
What are producers?
Photosynthetic organisms that manufacture organic substances using light, water, CO2 and minerals
What are consumers?
Organisms that get their energy from feeding on other organisms
What are primary consumers?
Consumers that eat producers
What are secondary consumers?
Those that consume primary consumers
What are saprobionts?
Organisms that break complex material in dead organisms down into simple molecules
What is a food chain?
A feeding relationship in which producers are eaten by primary consumers, they are eaten by secondary consumers, who are eaten by tertiary consumers
What is each stage in a food chain called?
A trophic level
What is a food web?
Many overlapping food chains
What is biomass?
The total mass of living material in a specific area at a given time
Why is it better to measure the dry mass?
The presence of water in an organism varies dependent on conditions
Describe the process of calorimetry
A sample of dry material is weighed and burned in pure oxygen. The ‘bomb’ is surrounded by a water bath and we measure the change in temperature of this water
Why is such a small percentage of the suns energy used in photosynthesis?
Reflected by clouds
Not all wavelengths of light can be used in photosynthesis
Light may not fall on chlorophyll
Limiting factors may reduce photosynthesis
What is gross primary production?
The total quantity of chemical energy stored in plant biomass at a given time
What is net primary production?
The chemical energy that remains when the loss of energy used in respiration has been accounted for
What is the equation for net primary production?
Net primary production = gross primary production - respiratory losses
Why is such a low percentage of energy transferred between trophic levels?
Not all of the organism is consumed
Some parts are consumed but can’t be digested so are lost in faeces
Urine
Heat is lost through respiration
Why are fertilisers needed especially in agricultural settings?
Normally, plants would die and decompose, returning their nutrients to the soil. In agriculture, the plants are removed before they can decompose so the nutrients must be returned in another way
What are natural fertilisers?
Consists of the dead and decaying parts of plants and animals
What are artificial fertilisers?
NPK fertilisers!
Mined from rocks and deposits and combined to produce the right ratio for the crop
How do fertilisers increase productivity?
Plants grow healthier and photosynthesise more
What is nitrogen used for?
DNA, amino acids, ATP
What are some of the detrimental effects of nitrogen fertilisers?
Leaching, eutrophication, reduced species diversity (nitrogen favoring species out-compete others so diversity decreases)