B5.2 Natural Selection And Evolution Flashcards
What is evolution?
The gradual change of species over time to suit a particular environment.
How do organisms evolve?
Natural Selection
What is survival of the fittest?
-Organisms best suited to their environment or more likely to survive and reproduce
-They then pass on these advantageous characteristics through their genes to their offspring
What is the process of natural selection?
-Organisms in a specie show variation.
-Survival of the fittest
-Genes from successful organisms are passed to the offspring in the next generation
-Process is repeated many times, leading to the development of a new species
What are some examples of evolution?
Peppered moths
-most were pale
-camouflaged against trees
-mutation occurred in which made them darker
-easily seen by birds and were eaten
-pale moths survive and reproduce
-Then came the industrial revolution
-Trees became covered in soot and turned black
-black moths were now camouflaged
-Over the years, dark peppered moths were more common
What are antibiotic resistant bacteria?
-Bacteria reproduces quickly
-evolves quickly
-when mutation occurs bacteria dies
-mutation may cause a resistance to antibiotics
-bacteria reproduce
-gene is passed on
-Whole species may be resistant to antibiotics
What are fossils?
Fossils are formed when animal and plant remains or traces are preserved in rocks.
What is a fossil record?
The fossil layers form a sequence showing that organisms have gradually changed over time
What are the steps for fossilisation?
-Reptile dies
-Flesh rots, leaving the skeleton to be covered in sand or soil and clay before it is damaged
-The skeleton becomes mineralised and turns to rock. The rocks shift in the earth with the fossil trapped inside
-Eventually, the fossil emerges as the rocks move and erosion takes place.
How are fossils used as evidence for evolution?
-Oldest rocks contain fossils of simple organisms like bacteria.
-More recent rocks contain fossils of complex organisms like vertebrates
-Supports the theory of gradual evolution from simple to complex life forms
How are plant fossils and animal fossils shown in the fossil record
-Plant fossils appear before animal fossils in the geological record
-Consistent with animals relying on plants for survival
How do fossil records show related organisms?
-Closely related organisms share a common ancestor
-Study of anatomical similarities (e.g bone structure) reveals evolutionary relationships
Why are there gaps in the fossil record?
- Not all organisms fossilise due to soft bodies or quick decomposition
-Some fossils are destroyed by natural events like volcanic eruptions
-Many fossils remain undiscovered
What other evidence is there for evolution?
Rapid changes in a species:
-Bacteria replicated rapidly, therefore scientists can study evolution in action.
Extinction:
-Species that don’t adapt to environmental changes die out.
Molecular comparison:
-Scientists have started comparing the DNA and proteins of different species
-They look at the order of nucleic acid bases, or at the order of amino acids in a protein
Where did Darwin go to for a scientific expedition?
Galapagos Islands
Before Darwin, how did people believe humans were made?
By God
What did Darwin read on his trip
-Whilst aboard on the HMS beagle, Darwin read Priciples of Geology by Charles Lyell
-It suggested that fossils were evidence of animals that had lived millions of years ago
What animal did Darwin observe on his trip?
-Finches
-He noticed that different islands had different finches
-The birds are closely related but their beaks and caws had different shapes and sizes
What did Darwin conclude from his observation on finches?
-The design of the finches beaks was linked to the food available on each island.
-A bird born with a beak more suited to the food available would survive longer than a bid whose beak was less suited
-Therefore there would be more offspring with this beak characteristic
-Over time the finch population on that island would all share this characteristic
Where was Alfred Russel Wallace working on his own theory of natural selection and evolution?
Borneo
Why did Wallace and Darwin produce joint writings?
Their ideas were similar
Who did Wallace and Darwin present their work to? When?
Linnean Society of London in 1858
What was Darwins book called? When did he publish it?
On the origin of species in 1859
Why was Darwins book controversial?
The theory of evolution conflicted with the commonly held belief that God had created all living things.
