A3.1 Diversity of Organisms Flashcards
What is an organism?
Any biological system that functions as an individual life form. All organisms are composed of cells.
What is a population?
A group of organisms of the same species in the same area. Even though they are the same specifies, the individual organisms of the population vary from each other. (ex. all humans are the same species, but we have differences / variations)
What is a community?
The populations of two or more different species occupying the same geographical area at the same time. There is great variation between different species.
what is the difference between a community and an ecosystem
- a community = the living organisms in an ecosystem
- an ecosystem = also includes the habitat, non-living things as well
what is variation?
A defining feature of life. It refers to differences between members of a group. Variation can be discrete or continuous.
“discrete” what does it mean?
- it refers to traits with distinct, qualitative categories
- ex: blood type or eye color
- usually influenced by ONLY ONE or a FEW genes. can also be influenced by the environment (but not usually)
“continuous” what does it mean?
- it refers to traits that vary along a spectrum or continuum
- ex: height or weight
- results from complex interactions between many differences genes (polygenic)
- often, environment plays a significant part in the expression of the phenotype
when is variation is inherited?
it is inherited during reproduction
- more variation (differences) = found in sexual reproduction than asexual
- in sexual reproduction, the offspring resembles the parents but is also different from them
where is variation found?
- variation exists at every level of biological variation
FOUND AT/IN:
- molecular levels (differences between genomes)
- cellular levels (differences between specialized cells in multicellular organisms)
- organisms (the difference in speeds of nerve impulses)
- ecosystems (differences between biomes)
what is variation within a species called?
called : intraspecies variation
genetic variation within a species = inheritable, meaning it is transmitted from parent –> offspring
what does variation within a species result from?
- mutation
- the changes in the sequences of genes in DNA
- gene flow
- the movement of genes between different populations of organisms
- meiosis
- the formation of egg and sperm which leads to the creation of new combinations of alleles
- sexual reproduction
- the random fertilization between egg and sperm
what does genetic variation in a population of organisms enable?
It enables some organisms to survive better than others in the environment in which they live
So, these individuals are more likely to reproduce and pass on their beneficial variation (natural selection)
- natural selection = the main force that drives evolution
the amount of variation between individual organisms depends on?
it depends on how closely related they are to each other
individuals within the same species will have ______ variation than those classified as different species
individuals within the same species will have less variation than those classified as different species
the largest amount of variation is between?
between organisms classified into different domains
What is the hierarchy of classification by linnaeus? (taxonomy)
REMEMBER: “do keep ponds clean or frogs get sick”
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Linnaeus’s system of classification was?
the first system of grouping organisms into specifies
- in this system, organisms are grouped and subdivided into ___ (see ppt)
how did Linnaeus group organsisms?
he based grouping strictly on “morphology”
- “morphology” = the clearly distinguishable shapes + forms of organisms
BUT: of course, basing grouping on morphology alone = limiting
(we know this now)
examples of how it’s limiting:
- genetically diverging populations may be hard to distinguish as unique species
- morphologically similar groups may be the result of convergent evolution and not actually members of the same species
