B6 Evidence For Evolution Flashcards
Complete the sentence
Scientists believe that all complex organisms on earth have evolved from ……………that existed 3500 million years ago.
Simple organisms
What provide evidence for evolution?
Fossils records and antibiotic resistance in bacteria.
What is a fossil?
Any trace of an animal or plant that lived long ago.
Where are fossils most commonly found?
In rocks
What can fossils tell us about ?
What organisms looked like and how long ago they existed.
What can be observed by arranging fossils in chronological order?
Gradual changes in organisms can be observed.
This provides evidence for evolution, because it shows how species have changed and developed over many years.
See p87 for diagram of how horse has evolved
.
What do random mutations in bacteria DNA cause?
New variants into the population
What can random variants in the DNA of bacteria, introducing new variants into the population, lead to?
These can lead to changes in the bacteria’s phenotype.
For example a bacteria could become less affected by a particular antibiotic.
Why is an advantage for bacterium to develop random mutations, that can lead to changes in their phenotype?
The bacterium is better able to survive, even in a host that is being treated with antibiotics.
So it lives for longer and reproduces many more times.
How do scientist continue to test the theory of evolution by natural selection?
By making observations and collecting new evidence.
What can the emergence of antibiotic-resistant bacteria be explained by?
The theory of evolution by natural selection ( as there is change in the inherited characteristics of a population over time)
Why is it easy to observe the theory of evolution by natural selection in bacteria?
Because reproduce very quickly, so scientists can observe evolution as its occurring, so it provides great support for the theory.
Why is the theory of evolution now widely accepted by the scientific community?
Because of strong evidence
How do genetic variants for antibiotic resistance arise in a population of bacteria?(1 mark)
By mutations
