Variataion And Selection Flashcards
(12 cards)
How can variation happen
Genetic
Environmental
What can happen in genetic variation?
Due to differences in DNA caused by variation as a result of sexual reproduction
Mutations- random changes in the number of chromosomes or structure of a gene.
What happens in environmental variation
Due to lifestyle of environment or combination of both. For example you have genes for height but your actual height depends on your health and diet.
Define continuous variation
The type of variation characterised by a gradual change in a characteristic across a population.
E,g height
Define discontinuous variation
The type of variation in which all the individuals can be clearly divided into two or more groups and there are no intermediate states. E.g tounge rolling
Define natural selection
The process in which the better adapted individuals survive and pass on their genes to their offspring.
Define evolution
A continuing process of natural selection that leads to gradual changes in organisms over time, which may lead to the formation of new species.
What are fossils
They are the remains of living organisms that have been preserved for millions of years
How are fossils useful when researching evolution
Fossils not only provide evidence for evolution, but they can also soho the different changes that took place in species over time.
Define extinction
A species is extinct if there are no living members of that species left.
Why are organisms endangered
Climate change, hunting by humans and habitat destruction
Define selective breeding
The selection and subsequent breeding of organisms chosen by humans for their desirable properties.
