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
