4.1 Species, communities and ecosystems Flashcards
What is a species?
Species are groups of organisms that are potentially interbreed to produce fertile offspring
What does it mean when two members of a species are interbreeding?
Two members of the same species mate and produce offspring
What is cross-breeding?
When members of different species breed together
What prevents two species’ genes from mixing?
The offspring produced by cross-breeding between species are almost always infertile, which prevents the genes of two species becoming mixed
What is a population?
A population is a group of organisms of the same species who live in the same area at the same time.
How likely is two populations of the same species going to interbreed?
If two populations live in different areas they are unlikely to interbreed with each other.
* This does not mean that they are different species. If they potentially could interbreed, they are still members of the same species
* Members of a species may be reproductively isolated in separate populations.
What may happen if two populations of a species never interbreed?
They may gradually develop differences in their characters e.g. recognizable differences
Until when are two populations who began as the same species considered as different species?
Until they cannot interbreed and produce fertile offspring
What prevents two species’ genes from mixing?
The offspring produced by cross-breeding between species are almost always infertile, which prevents the genes of two species becoming mixed
What are the two method of nutrition for species?
Methods of obtaining carbon compounds that are needed for growth and reproduction is divided into Autotrophic or heterotrophic method of nutrition (A few species have both methods)
What is autotrophic organisms?
Organisms that make their own carbon compounds form carbon dioxide and other simple substances
* self-feeding
What are heterotrophic organims?
Organisms that obtain their carbon compounds from other organisms are heterotrophic, which means feeding on others
What is mixotrophic?
Organisms that are not exclusively autotrophic or heterotrophic are mixotrophic.
* e.g Euglena gracilis has chloroplasts and carries out photosynthesis when there is sufficient light, but can also feed on detritus or smaller organisms by endocytosis
How are heterotrophs divided into groups?
They are divided according to the source of organic molecules that they use and the method of taking them in (consumers, detritivores, saprotrophs)
How are plants autotrophic?
- They make their own complex organic componds using carbon dioxide and other simple substances
- The energy supply they need to do this is obtained by absorbing sunlight
- Their method of autotrophic nutrition is therefore photosynthesis and they carry it out in chloroplasts
What makes a algae or plant parasitic?
- They do not contain chloroplasts and they do not carry out photosynthesis
- They grow on other plants, obtain carbon compounds from them and cause them harm.
- They are therefore parasitic
What are consumers?
Consumers or heterotrophs that feed on living organisms by ingestion.
* They ingest their food meaning that they take in undigested material from other organisms.
* They digest it and absorb the products of digestion
e.g. paramecium take the food in by endocytosis and digest it inside vacuoles; lions take food into their digestive system by swallowing it
How are heterotrophs divided? What are the different groups?
They are divided according to the source of organic molecules that they use and the method of taking them in
* Consumers, detritivores, saprotrophs
How are consumers sometimes divided up into?
Into trophic groups according to what other organisms they consume
* Primary consumers feed on autotrophs; secondary consumers feed on primary consumers, and so on
Why don’t most consumers fit into trophic groups?
They do not fit neatly into any one of these rooms because their diet includes materials from a variety of trophic groups
What are detritivores?
Detritivores are heterotrophs that obtain organic nutrients from the detritus (waste or debris of any kind) by internal ingestion.
What organic matter do organisms discard in large quantities?
- Dead leaves and other parts of plants
- Feathers, hairs and other dead parts of animal bodies
- Feces from animals
Why do dead organic matter rarely accumulate in ecosystems?
It is used as a source of nutrition by two groups of heterotroph - detritivores and saprotrophs
Why do dead organic matter rarely accumulate in ecosystems?
It is used as a source of nutrition by two groups of heterotroph - detritivores and saprotrophs
What are detritivores?
- Organisms that ingest dead organic matter and then digest it internally and absorb the products of digestion
- Large multicellular detritivores such as earthworms ingest the dead matter into their gut
What are detritivores?
- Organisms that ingest dead organic matter and then digest it internally and absorb the products of digestion
- Large multicellular detritivores such as earthworms ingest the dead matter into their gut
What are saprotrophs?
Heterotrophs that obtain organic nutrients from dead organic matter by external digestion
How do saprotrops digest externally?
Secrete digestie enzymes in to the dead organic matter and digest it exernally
* They then absorb the products of digestion
* Many types of bacteria and fungi are saprotophic
How do saprotrops digest externally?
Secrete digestie enzymes in to the dead organic matter and digest it exernally
* They then absorb the products of digestion
* Many types of bacteria and fungi are saprotophic
What are saprotrophs also known as?
Decomposers because they break down carbon compounds in dead organic matter and release elements such as nitrogen into the ecosystem so that they can be used again by other organisms
How is a community formed?
By populations of different species living together and interacting with each other
What are all species dependant on for their long term survival?
All species are dependent on relationships with other species for their long-term survival
Why can a population of one species never live in isolation?
Because they are dependent on relaitonships with other species for long term survival
What is an abiotic environment?
Non living surroundings
- Air, water, soil or rock
How do an abiotic environment of rocky short or cliffs exert a powerful ingluence over the organisms?
The wave action on a rocky shore creates a very specialized habitat and only organisms adapted to it can survive
On cliffs, the rock type determines whether there are ledges on which birds can nest
What is an example of living organisms influencing the abiotic environment?
Sand dunes
- They develop along coasts where sand is blown up the shore
- Specialised plants grow in the loose wind blown sand
- The roots of these plants stabilize the sand and their leaves break the wind and encourage more sand to be deposited
What is an ecosystem?
A single highly complex interacting system between a community of organisms in an area and their non-living environment
Where do autotrophs and heterotrophs obtain inorganic nutrients from?
From the abiotic environment
What are some of the chemical elements living organisms need?
- Carbon, hydrogen and oxygen -> to make carbohydrates, lipids and other carbon compoinds on which life is based
- Nitrogen and phosphorus are also needed to make many of these compounds
- Appropximately 15 other elements are needed by living organisms. Some of them are used in munute traces only, but they are nonetheless essential
What are some of the chemical elements living organisms need?
- Carbon, hydrogen and oxygen -> to make carbohydrates, lipids and other carbon compoinds on which life is based
- Nitrogen and phosphorus are also needed to make many of these compounds
- Appropximately 15 other elements are needed by living organisms. Some of them are used in munute traces only, but they are nonetheless essential
What do autotrophs obtain their needed elements from in an abiotic environment?
Inorganic nutrients
What do heterotrophs obtain their needed elements from in an abiotic environment?
From their food
but also other elements in inorganic nutrients (e.g. sodium, potassium and calcium)
What do heterotrophs obtain their needed elements from in an abiotic environment?
From their food
but also other elements in inorganic nutrients (e.g. sodium, potassium and calcium)
How is the supply of inorganic nutrients maintained?
By nutrient cycling
- These elements an be endlessly recycled
- Organisms abosrb the elements that they require as inorganic nutrients from the abiotic enviornment, use them and then return them to the environment with the atoms unchanged
What is nutrient cycling?
The recycling of chemical elements often passes an element from organism to organism before it is released back int o the abiotic environment
What are the 3 requirements for sustainability in ecosystems?
- Nutrient availability
- Detoxification of waste products
- Energy availability
Why is sunlight important in sustainability?
Energy cannot be recycled, so sustainability depends on continued energy supply to ecosystems. Most energy is supplied to ecosystems by light from the sun
Why is sunlight important in sustainability?
Energy cannot be recycled, so sustainability depends on continued energy supply to ecosystems. Most energy is supplied to ecosystems by light from the sun
