Variation Flashcards
What is variation?
Living organism that belong to same species resemble each other, but usually differ in a number of ways.
What are the 2 causes of variation?
Genetics
The environment
How can genetics be varied?
Mutations in the DNA.
Through sexual reproduction.
What are some examples of genetic variation?
Eye colour
Blood group
Tongue-rolling
Genetic conditions - cystic fibrosis, Down’s syndrome
How can the environment be varied?
Climate
Nutrient availability
Soil, e.g. pH or moisture levels
Lifestyle
What are some examples of environmental variation?
Height of pea plant
Shoe size
What type of variation is genetic variation?
Discontinuous variation
What type of variation is environmental variation?
Continuous variation
What type of graph can be used to showcase continuous variation?
Histogram
How does a histogram showcase continuous variation?
Gradual change
No distinct groups
Values over a range
What is special about a histogram?
No spaces between bars.
What type of graph can be used to showcase discontinuous variation?
Bar chart
How does a bar chart showcase discontinuous variation?
Distinct groups
No overlap
What is special about a bar chart?
Spaces between bars.
What are some examples of discontinuous variation?
Blood groups
Tongue-rolling
Attached/detached ear-lobes
Shoe size
What is continuous variation?
Type of variation shown by gradual change in a characteristic in a population.
What is discontinuous variation?
Other type of variation in which all individuals can be clearly divided into two or more groups and no intermediate states.
What is natural selection?
Process in which better adapted individuals survive (at expense of less well adapted ones) and pass on their genes to their offspring.
Where is natural selection important?
Where there is competition for natural resources.
What are the 3 elements of natural selection?
Difference between phenotypes
Differential survival
Differential reproductive success
What is an example of the 3 elements of natural selection?
- Some grey squirrels can run faster than others and get away from predators.
- Fastest squirrels survive while slower ones get caught.
- Fastest squirrels will pass their genes to their offspring.
What is an example of natural selection in action?
Antibiotic resistance
What is involved in antibiotic resistance?
When treated with antibiotic some bacteria may already be resistant due to mutation.
These bacteria survive as rest are killed and reproduce with less competition from non-resistant bacterial strains.
Resistance bacteria survive to breed and pass on resistant gene to offspring.
Over time antibiotic resistant bacteria become dominant type in population.
What is evolution?
A continuing process of natural selection that leads to gradual changes in organisms over time, which may lead to formation of a new species.
What are the reasons that some people do not accept the theory of evolution?
- Contradicts some religious beliefs.
- Very long time scales means very difficult to see it happening.
What is extinction?
When there are no living members of a species left.
What are some examples of species that were not well enough adapted to survive?
Mammoths and dinosaurs.
What does endangered mean?
Risk of extinction.
What are some reasons for why many organisms are endangered?
Climate change
Hunting by humans
Habitat destruction
What are some examples of endangered species today?
Mountain gorillas and many species of large cats
How can we slow down the rate of extinction?
Legislation preventing hunting of endangered species.
International climate change agreements.
Nature reserve to protect habitats.
Education to help people protect their environment.
What are fossils?
Fossils are the remains of living organisms that have been preserved (usually in rock) fro millions of years.
How can fossils provide good evidence for evolution?
Scientists can compare fossils of different stages to see how species have changed over time.
Different stages can be dated as possible to date rocks.
Fossil record can also show when new species appeared and give information about environment an animal lived in.
