Chapter 32 - Energy Flow, Food Chains and Food Webs Flashcards
Explain why the sun can be described as the principle source of energy
All energy originates from the sun, and life cannot exist without energy. The sun’s energy sustains all terrestrial and aquatic life
Describe the process by which energy is transferred from the sun to plants and animals
Chlorophyll in green plants traps light energy and uses it during photosynthesis. Light energy is then converted into chemical energy, which is stored in organic molecules like proteins. Animals consume plants and obtain the organic molecules. During respiration, the energy is then released for use by living organisms
Describe the non-cyclical flow of energy
- Energy flows in only one direction through an ecosystem
- Energy never returns to the sun
- Energy can not be created or destroyed, only changed from one form into another
- During transformation, some energy is converted to heat energy
Define ecology
The study of living organisms in relation to one another and to their environment
Define an ecosystem
Self-contained area which include all living organisms and their non-living environment
Describe a producer
Organims with the ability to produce their own nutrients from inorganic sources using light, carbon dioxide and water. They are autotrophic and can produce nutrients by photosynthesis
Describe a consumer in general
An organism which depends on the nutrients produced by a producer and are unable to utilise light energy to manufacture nutrients. They must therefore consume other organisms in order to obtain nutrients
Describe a primary consumer
Herbivore feeding on plants
Describe a secondary consumer
Carnivores feeding on the flesh of other organisms
Describe a tertiary consumer
Carnivore feeding on the flesh of other carnivores and herbivores
Describe a quaternary consumer
Carnivores feeding on the flesh of other organisms
Name one adaptation of a herbivore
Dentition and digestion especially adapted to deal with tough plant material
Name one adaptation of a carnivore
Powerful claws and dentition adapted to tear flesh
Describe a scavenger
Especially carnivorous animals that feed on dead animals rather than hunt for prey
Name one function of detrivores in the ecosystem, and also name what they feed on
Detrivores feed on dead organic waste. Detrivores speed up decomposition by consuming dead matter and increasing the surface area availible to putrifying bacteria
Explain the process of decomposition
Decomposers obtain nutrients by feeding on dead organisms and breaking them down into smaller substances, making nutrients availible to producers
Name one function of decomposers
Clean up the environment
Describe a decomposer
Saptrotrophic micro-organisms which exploit the energy of dead organisms by breaking or decaying them down
Describe a predator
An organism which obtains nutrients by killing and feeding on other animals
Define a population
A group of organisms of the same species which occupies a particular place over a given period of time and has the ability to interbreed and produce fertile offspring
Define a species
Organisms which have the potential to interbreed and produce fertile offspring of the same species
Define a habitat
A place or part of an ecosystem where organisms live, because the environmental conditions are essentially uniform
Define a community
The total of all populations living in a habitat and interacting with one another in an ecosystem
Explain energy losses
- Energy is lost everytime energy passes through a link in a food chain
- On average only one 10th of energy is transferred from one organism to the next
- The longer the food chain, the more energy will be lost
Explain why all light falling on plants is not absorbed
- Some light energy is reflected
- Plants appear green due to the wavelengths of relected light
- Reflected light falls on other objects and are reflected back into space
- Most of the light energy absorbed is not used for photosynthesis
- Excess energy is lost as heat
Explain why all energy from plants are not tranferred to herbivores
- Herbivores only eat the leaves
- Herbivores are not able to digest all the plant material
- Some energy is lost when the leaves fall
Explain why all the energy from herbivores is not transferred to carnivores
- Herbivores use obtained energy and energy is lost due to loss of heat
- Energy is used during urination
- Energy is lost during egestion
- Not all parts of a herbivore can be consumed
- Some parts are indigestible
- Energy is lost during growth
- Energy is lost in hair loss or milk production
- Energy is lost during respiration
Define ecological efficiency
The percentage of energy transferred from one trophic level to the next
What does a pyramid of numbers display?
The total number of individual organisms at each trophic level
Name three problems associated with pyramids of number
- All organisms are counted, regardless size
- The pyramid may be inverted
- The range of numbers may be enormous, causing difficulty when drawing the pyramid to scale
Name the problems associated with pyramids of biomass
- Impossible to measure the biomass of all living organisms
- Time affects results
- One organism may have a much bigger mass than the organisms feeding of it
- Inversion
State why pyramids of energy is more widely used
Comparisons can be made between trophic levels of different ecosystems
