B5.2: Natural Selection And Evolution Flashcards
What is Evolution?
The gradual change in inherited characteristics of a population overtime
How do organisms evolve?
Through natural selection
What is natural selection?
The process where the organisms that are better adapted to an environment will survive and reproduce. This means that alleles that are beneficial to surviving in that environment are passed onto offspring
Over many years of natural selection, it leads to…
Evolution
What are fossils?
Formed when animal and plant remains, or traces, are preserved into rocks.
What is step number 1 of fossil formation?
Reptile dies
What is step number 2 of fossil formation?
Flesh rots, leaving skeleton covered by sand and clay before it gets damaged
What is step number 3 of fossil formation?
Fossils would normally, mostly be found close to cliffs, where most sand and clay would be found
What is step number 4 of fossil formation?
Over millions of years, skeletons get mineralised by pressure of the formation of the rocks above
What is step number 5 of fossil formation?
Eventually, the fossil emerges as the rocks move and erosion takes place
What are homologous structures?
Parts of an organisms body that are similar in structure in different (but related) species
What are analogous structures?
Structures that perform the same or similar function, but evolved independantly in unrelated species
What are vestigal structures?
Parts of an organisms body that have no known function. It’s guessed that these were functional in recent ancestors but have lost their function through evolution
Whats an example of a vestigal structure?
Human tailbone
Whats an example of a homologous structure?
Arms of all mammals are similar
Whats an example of an analogous structure?
Sweet potato and potato
Wings of birds and butterflies
What is competition?
When individuals or groups of organisms compete for similar resources such as territory, mates, water and food in the same environment
How does comparative embryology add evidence to the idea of evolution?
Comparative embryology shows that embryos of different species look similar at early stages, suggesting they share common ancestors.
How does molecular biology add evidence to the idea of evolution?
Molecular biology provides strong evidence for evolution by showing that all living organisms share similar genetic material, like DNA. The more closely related species are, the more similar their DNA is
How does observed examples add evidence to the idea of evolution?
Antibiotic resistant bacteria are becoming more common, which is micro scale evolution
How does extinction add evidence to the idea of evolution?
Species that do not adapt to environmental changes die out. Scientists estimate that more than 99% of all species that have ever lived are now extinct
In 384-322 BCE, most people believed in spontaneous generation. What is that?
Which proposed that life arose from non living material called pneuma
When Darwin was born in 1809
Many british people believed that all species on Earth were created by God
In 1831, Darwin…
Joined a scientific expedition to th Galapagos island. Whilst travelling he read ‘Principles of geology’ by charles lyell. Lyell sugested that fossis were evidence than niamh’s lived millions of years ago.
