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BIO - 4.2.2 Classification and Evolution > Variation > Flashcards

Flashcards in Variation Deck (6)
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What is variation?

- Variations are differences in characteristics between organisms.
- Intraspecific variation: variation within species.
- Interspecific variation: variation between different species.


Causes of variation

- Organism's genetic material: differences in genetic material an organism inherits from parents leads to genetic variation.
- Environment in which organism lives.


Genetic factors

1) Alleles: genes have different alleles.
2) Mutations: changes to DNA sequence and genes leads to change in proteins that are coded for. Protein changes can affect physical and metabolic characteristics.
3) Meiosis: gametes are produced by process of meiosis in organisms. Each gamete receives 1/2 genetic content from parent cell. Genetic variation increased by independent assortment and crossing over.


Environmental and genetic causes

- Genetic factors determine the characteristics an organism's born with, but environmental factors can influence how some characteristics develop e.g height.


Continuous variation

- Characteristic that can take any value within a range is said to show cont. variation.
- Continuum: graduation in val. from 1 extreme to other of a characteristic.
- Characteristics that show cont. variation are not controlled by single gene but is polygenic and can be influenced by environmental factors.


Discontinuous variation

- Characteristic that can only result in certain values is said to show discount. variation.
- Variation determined purely by genetic factors falls into this category.