B1- evolution Flashcards
What is the theory of evolution?
different species have developed over time from simple life forms through natural selection. These simple life forms first developed more than three billion years ago (as the Earth is believed to be about 4.5 billion years old).
Who was Charles Darwin?
Charles Darwin was an English naturalist. He studied variation in plants and animals during a five-year voyage around the world in the 19th century. He explained his ideas about evolution in a book called On the Origin of Species, which was published in 1859.
Why did people not believe Charles Darwin’s theory at first?
Darwin’s theory conflicted with religious views that God had made all the animals and plants on Earth
Darwin did not have enough evidence at the time to convince many scientists
it took 50 years after Darwin’s theory was published to discover how inheritance and variation worked.
Who was Jean-Baptiste Lamarck?
Jean-Baptiste Lamarck was a French scientist who developed an alternative theory of evolution at the beginning of the 19th century.
What are Lamarck’s theory?
A characteristic which is used more and more by an organism becomes bigger and stronger, and one that is not used eventually disappears
Any feature of an organism that is improved through use is passed to its offspring.
What is the major flaw of Lamarck’s theory?
Lamarck’s theory cannot account for all the observations made about life on Earth. For instance, his theory implies that all organisms would gradually become complex, and simple organisms disappear. On the other hand, Darwin’s theory can account for the continued presence of simple organisms.
How do we classify different organisms?
Different organisms can be classified by studying their similarities and differences. These studies also help us to understand the evolutionary relationships between different organisms.
What do evolutionary trees show?
Evolutionary trees are used to represent the relationships between organisms.
How does natural selection work?
individuals in a species show a wide range of variation
this variation is because of differences in their genes
individuals with characteristics most suited to the environment are more likely to survive and reproduce
the genes that allow these individuals to be successful are passed to their offspring.
Individuals that are poorly adapted to their environment are less likely to survive and reproduce. This means that their genes are less likely to be passed on to the next generation. Given enough time, a species will gradually evolve.
What are mutations?
A random change in the DNA of an organism due to an error in DNA replication.
What happens if a mutation occurs?
Mutations cause changes in genes. When new forms of a gene appear because of mutation, a rapid change in a species may happen if the environment changes.
How do peppered moths support the theory of evolution?
Before the industrial revolution in Britain, most peppered moths were of the pale variety, meaning that they were camouflaged against the pale birch trees that they rest on. Moths with a mutant black colouring were easily spotted and eaten by birds. This gave the white variety an advantage and they were more likely to survive to reproduce.
Airborne pollution in industrial areas then blackened the birch tree bark with soot. This meant that the mutant black moths were now camouflaged, while the white variety became more vulnerable to predators. The black variety now had the advantage and were more likely to survive and reproduce. Over time, black peppered moths have become far more numerous in urban areas.
How do antibiotic-resistant bacterium support the theory of evolution?
Microorganisms such as bacteria and viruses reproduce very rapidly. They can evolve in a relatively short time. One example is the bacterium E. coli. Its DNA can be damaged or changed when it reproduces. Most of the time this causes the death of the bacterial cell.
Occasionally, the mutation is beneficial for the bacterial cell. For example, it may allow resistance to an antibiotic. When that antibiotic is present, the resistant bacteria have an advantage over bacteria that are not resistant.
