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
