Ecology Flashcards
(40 cards)
Species
A group of organisms that can interbreed and give fertile offspring.
Population
A group of individuals of the same species living at the same
area at the same time.
Gene Pool
All the possible genes and their alleles within a species.
Evolution
Gradual change in the heritable characteristics of an
individual.
- Change can be caused by genetic mutations, either beneficial
or detrimental. - Result of environmental pressure that favours one characteristic within the species.
Speciation
A process where a new species is formed from a pre-existing species.
Habitat
Environment in which a species normally lives, or the location
of a living organism.
Population
A group of organisms of the same species who live in the same
area at the same time.
Community
A group of populations living and interacting with each other in
the same geographical area.
Autotrophs
Synthesize their own organic compounds from simple
inorganic compounds found in the abiotic environment.
- By absorbing carbon dioxide, water, and other inorganic nutrients from the environment for synthesis (e.g., plants, algae, cyanobacteria (all of
these are photosynthetic organisms). - Aquatic ecosystems, carbon can be presented as hydrogen carbonate ions.
- Formed when water & carbon dioxide combine to form carbonic acid, dissociates to produce hydrogen carbonate ions
- Aquatic autotrophs absorb and use dissolved carbon dioxide and hydrogen carbonate ions in photo synthesis
Autotrophs are referred to as producers.
Heterotrophs
Obtain organic compounds from other living organisms (e.g.,
humans, insects, fish, etc.).
Heterotrophs are referred to as
consumers.
Divided into three - Consumers, detritivores and saprotrophs
Consumers
Organisms that obtain organic matter from other living or recently killed organisms
- Primary consumer: eats autotrophic organisms → herbivore
- Secondary consumer: eats herbivores → carnivore
- Tertiary consumer: eats secondary consumer → top carnivore
top carnivore can also be a quaternary consumer, depending on
the food chain
Detritivores
Decomposers that internally digest dead organic matter like leaves and carcasses
- Earthworms and woodlice
Saprotrophs
Decomposers that live in or on dead organic matter and externally digest
it, by secreting digestive enzymes and absorbing the products of digestion
- Fungus and bacteria
Heterotrophic plants and Algae
Most plants & algae are autotrophs, but some species dont’ make their food using photosynthesis,
Instead use carbon compounds from other organisms, heterotrophs
- Some obtain carbon compuds from plants. Dodder( Cuscuta europaea). Feeds on stems
- Others from funfi living int tree roots, gosht orchid(Epipogium aphyllum)
So not all plant and alga are autotrophic
Food Web
Complex network of feeding relationships in a community
Abiotic Environment
Non-living surrounding of a community
Community interacting with abiotic environment make ecosystems
Quadrant sampling in communities
Quadrat- Square sample used in ecological research
Mesocosms
Small experimental area set up in an ecological research programme.
- Autotrophs- Produce carbon compounds & regenerate oxygen, used in cell respiration
- Saprotrophs- Decompose dead organic matter and recycle nutrients
- Consumers & detritivores- Ussually included.
Large animals are unethical as they cannot obtain enough food or oxygen
Sunlight
- Main source of energy in ecosystems
- In a food chain, the most abundant level of organisms comprises autotrophs (plants and algae). producers.
- Since autotrophs are mainly
photosynthetic organisms, sunlight is required as a main source of energy. To convert it into organic compounds and obtain the necessary nutrients for survival. - Without sunlight, producers would not survive and primary
consumers would not be able to feed, disrupting the food chain.
Energy Source
Most organisms obatin their energy in one of the two ways
- Plant, algae & some bacteria absorb light energy & convert it by photosynthesis into chemical energy in carbon compounds. Known as producers
- Consumers, detritivores & saprotrophs obtain energy from their food. Energy in carbon compounds can pass from organisms in organisms on the food chain.
All food chains start with a producer that mad carbon compounds by photosynthesis.
Light is essential for the community
Energy flow in ecosystems
- Food chain is a sequence showing the feeding relationships and energy flow between species sharing a habitat.
- The arrow shows the direction of the energy flow (energy is
transported by ingestion to the next organism in the food chain). - Organism’s position in a food chain or web is a tropic level
Energy loss
Energy enters the ecosystem as sunlight, and is absorbed with about 20% efficacy by
autotrophic producers and transformed into chemical energy
Chemical energy is transferred from one trophic level to the next by means of feeding.
The chemical energy stored in bonds is released and made
available to an organism when carbohydrates, lipids, proteins and nucleic acids are digested
At each step, only about 10% of the energy is successfully
transferred to the feeding
organism. This is because energy is lost in several ways:
How Energy is lost
- Not the entire organism is eaten. Bones, cartilage, hair and gall bladders are eaten
- Loss of carbon dioxide, water and other waste products throughout the organism’s life
- Some organisms die and decay before being eaten
- Warm-blooded and moving organisms lose more energy as heat
- Parts of organisms are indigestible, cellulose in food for humans. Undigested parts are egested in feces
- Energy losses restrict length of food chains and the biomass of the higher trophic levels
Energy Pyramid
Diagram used to show the flow of energy through each topic level
- Producers- Primary consumers - secondary consumers - tertiary consumers
- Bar becomes 10 times smaller, as only 10 of energy is transferred
- Energy expressed in = kilojoules per square meter/pear year
