B14.1 - 14.7 - Variation And Evolution✔️ Flashcards
Define variation?
Is the difference in the characteristics of individuals in a population
Define natural selection?
Natural selection is a process where organisms that are better adapted to an environment will survive and reproduce
How do mutations impact organisms?
Mutations can take place when a cell divides and is a result of a change in the DNA code - some mutation are harmful and can result in the organisms death very rarely a mutation produces an adaption that makes the organism better suited to its enviorment
State the theory of evolution by natural selection ….?
All species of living things have evolved from simple life forms that first developed more than 3 billion years ago - evolution through natural selection produces changes in the inherited charcteristics of a population over time
Summarise evolution?
-individual organisms within a particular species may show a wide range of phenotype and genetic variation
-individuals with characteristics most suited to the enviorment are most likley to survive
-the alleles that have enabled these individuals to survive are then passed on to the next generation
How can a mutation lead to a change in species?
Rarely a mutation leads to a new phentotypes - If the new phenotype is suited to an enviormental change it can lead to a relatively rapid change in the species
4 Uses of selective breeding?
-disease resistance in food crops
-animials that produce more milk or meat
-domestic sogs and farm animials with a gentle nature
-large,unsual,bright,heavlt scented flowers
How does selective breeding work?
Farmers select animials from a mixed population that have useful or desirable characteristics they breed these animials together and select the offspring that best show these characteristics this continues over many generations
3 factors that may result in variation?
- genes that they have inherited
- conditions in which they have developed
- combination of genes and the enviorment
What can cause a rapid change in species?
Very rarely mutations will lead to a new phenotype - if a new phenotype is suited to an enviormental change it can lead to a relativley rapid change in the species
How can new species be formed?
If two populations of one species become so different in phenotype (observable characteristics) that they can no longer intebreed to produce fertile offspring they have formed two new species
Define evolution?
Change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species
Define selective breeding?
Process where humans artificially select the plants or animials to breed for desired genetic characeteristics eg crops that are disease resistant
What does selective breeding involve - explain the process?
Involves choosing parents with the deired characteristics from a mixed population - they are bred together - offspring that best show the desired characteristics are bred together this repeats over many generations - until all offspring show the desired characetristics
Explain in 4 steps the process of selective breeding?
1)from existing stock, select the ones which best display desired characetristics
2)breed them together
3)select the best of the offspring and breed them together
4)continue process over many generations - until the desired trait gets stronger