Ecology is the study of organism within their environment, including the way in which organisms interact with each other & the non-living part of the environment
Terms used in ecology #
1. Habitant
- The place where organism live e.g. a pond.
- The term habitant is often used to mean the kind of place in which a particular species of organism can live, such as the range of pH of the water & the range of dissolved oxygen concentration in which it is found.
2. Population
- Refers to all the organism of one species that live in the same place at the same time, make up a population on that species.
- A population is a breeding group or it includes all the individuals of that species which can interbreed with each other.
- The population of dark weed is made up of the entire dark weed found in the pond.
- A group of organisms of one species occupying defined area & usually isolated to some degree from other similar to groups.
3. Community
- All organisms of every species in a habitant. Communities may remain fairly stable over a period of time or may be in a progress of gradual change (succession).
- Eventually, succession may result in the formation of a stable community known as climax community.
- Any group of organisms belonging to a number of different species that co- exist in the same habitant/ area & interact through trophic & spatial relations.
4. Ecosystem.
- The inter-relationship of the living (biotic) and non-living (abiotic) elements in any biological system.
- It is a self-contained unit.
- A community of organisms & their physical environment interact as an ecological unity.
5. Niche
- Is a place which is occupied by particular organisms in an environment &its role in that environment?
- Within an ecosystem each species of organisms plays a particular role
- The term niche is used to describe this role.
- An organism niche has many aspects.
- It includes what the organism eats, how it captures its food, what eat it, the secretory material produces & so on behavior.
- Within a community, each species has a niche which differs in at least some ways from the niches of all the other species in the same community. They will be competition for available resources.
Flow of energy #
- Living cells require energy for many purposes which are locomotion, growth e.t.c
- The immediate source of energy is almost ATP which is produced for respiration.
- Respiration transfers energy from other organic molecules such as glucose to ATP molecules.
- The energy in these organic molecules can be thought as organic chemical energy.
- There are 3 types of chains.
- A food chain is a sequence of series of organisms feeding on one another.
Grazing food chain #
- this is based on living plants
- Grass > cow > lion > decomposition.
- Produces of the first level, they receive max energy which is able to sustain a large number of organisms.
- They are autotrophic organism, e.g. grass, leaves
- Primary consumers: food directly on producers, these are herbivores
- Secondary consumers: feed on herbivores usually carnivores.
- Tertiary consumers: can be omnivores, herbivores or carnivores.
- Decomposers: they feed on saprophytic organisms
Detrital food chain #
- This is based on dead plants materials
- Grass > earth > worms > shrew.
Food web #
- Is a group of interconnected food chains because there are sustaining organisms which do not depend on one type after food?
Parasitic food chain #
- Rose > bush > aphids > spider > insect > bird > lawks.
- At each stage in the food chain energy containing materials are transformed
- The stage of the food chain is reorganized as feeding levels or trophic levels.
- Most food chain with other chains, since most organisms are the prey of more than one predator.
- Only a small portion of the energy containing materials obtained by a consumer as it feed becomes built into the organism itself.
- This is partly because most of the food is undigested & partly because most of the remainder is used to provide energy for processes e.g. movement, digestion, excretion & reproduction.
- More energy is lost & the last receive a small amount of energy.
- Shorter food chain – more energy is required by the last feeding level.
Questions and model answers #
Explain how energy is lost from producers to secondary consumers? #
- Respiration
- Waste/urine/feaces/dead plants/excretion
- Plant are swept/ away migrate
- Not all parts of the plant / primary consumers are digestible
- Energy losses to decomposers
Describe how energy flows in an ecosystem. [8] #
- source of energy, the sun
- sun to plants/producers
- conversion of light to chemical energy
- from plants/ producers to primary consumers
- examples of a food chain
- secondary to tertiary consumers
- loss of energy at each tropic level/loss as heat/ respiration /excretion/egestion to the atmosphere
- dead and waste material to decomposers/detritus feeders to the atmosphere
- unidirectional flow of energy.
Ecological Organization & Nitrogen cycle questions and answers
