A3.1 Unity and Diversity Flashcards
Define Species
A group of organisms that have very similar biological and physical traits, but have variations in their genetic material. They are able to produce fertile offspring (offspring that can also reproduce).
Define Organism
Any biological system that functions as an individual life form. All organisms composed of cells.
Define Population
A group of organisms of the same species in the same area. Even though they are the same species, the individual organisms of the population vary from each other.
Define Community
Communities are the populations of two or more different species occupying the same geographical area at the same time. There is a great variation between different species.
Define Variation
Variation is a defining feature of life. Variation refers to differences between members of a group; can be discrete or continuous.
More found in sexual reproduction than asexual.
Explain Discrete Variation
Traits that can be put into distinct qualitative categories.
Cause: Usually influenced by environment; not significantly though.
E.g. Blood type, Petal colour, Dominant hand.
Can be shown using a bar chart.
Explain Continuous Variation
Traits that vary along a quantitative continuum.
Most types of bio. var. = continuous.
Cause: Results from complex interactions between many different genes, often with environment playing significant part in the expression of the phenotype.
E.g. Height, Body mass, Root length of plants.
Where does variation occur?
Every level of biological variation:
- Molecular
- Cellular
- Organisms
- Ecosystems
Explain Intraspecies variation
Variation within a species. Inheritable if genetic, meaning transmitted from parent to offspring.
Enables some to survive better in the environment they live in. As a result, more likely to reproduce and pass on beneficial variation. Part of natural selection: main force that drives evolution.
How does Genetic variation within a species occur?
Mutation: changes in sequences of genes in DNA
Gene flow: movement of genes between different population of organisms.
Meiosis: formation of egg and sperm which leads to creation of new combinations of alleles.
Sexual reproduction: random fertilization between egg and sperm.
Explain variation between species
Amount of variation between individual organisms depends on how closely related they are. Largest amount of variation between organisms classified into different domains.
Linnaeus’s system of classification
Check online.
Organisms grouped and subdivided into smaller and smaller categories of organisms, with species of as smallest, most exclusive grouping.
How are organisms grouped into species?
- Linnaues’s time period strictly based it on ‘morphology’, clear distinguishable shape and form of organisms.
- Technology + scientific knowledge progressed, morphology alone has limitations.
How are names assigned to organisms?
Two-part name: Genus name + Species name.
Homo sapiens.
Explain hybrids
Offspring between two different species from the same genus that reproduced sexually, that may or may not be able to reproduce themselves. Depends on chromosome number.
E.g. Donkey and Horse makes mule: cannot reproduce due to 63 chromosome: mismatched chromosomes prevent homologous chromosomes from pairing during meiosis.
Are species distinct groupings?
No, mere approximations
E.g. colour of beetle up to subjectivity.
