B15(Genetics And Evolution) Flashcards
What was Mendel’s observation
The inheritance of each characteristic is determined by ‘units’ that are passed on unchanged to descendants
In the late 19th century behaviour of …
Chromosomes during cell division was observed
In the early 20th century it was observed that …
-Chromosomes and Mendel’s ‘units behaved in similar ways
-This led to the idea that the ‘units’ (genes) were located on the chromosomes
In the mid 20th century the structure of …
DNA was determined and the mechanism of gene function was worked out
What was Lamarck’s theory of evolution
-Changes that occur in an organism during its lifetime can be inherited
-All animals evolved from primitive worms
What was Charles Darwin’s theory of evolution
All living organisms have evolved from simpler life forms by natural selection
What was Darwin’s 1st main idea about evolution
The individual organism in a particular species tend to show a wide range of variation for each characteristic
What was Darwin’s 2nd main idea about evolution
-Reproduction always gives more offspring than the environment can support
-The organism that have inherited the characteristics most suited to the environment are more likely to survive and breed successfully
What was Darwin’s 3rd main idea about evolution
When they breed they pass on the characteristics that have enabled them to survive to the next generation
Why was Darwin’s theory of evolution by natural selection gradually accepted
-conflict with the widely held belief that God made all the animals and plants on Earth
-Insufficient evidence
-no mechanism for explaining variation and inheritance
How do new species arise
-isolation: when 2 populations of a species becomes separated
-genetic variation between the populations
-natural selection that operates differently on the 2 populations
-speciation: where the populations become so different that successful interbreeding is no longer possible
Fossils are the …
Remains of organisms from millions of years ago that can found in rocks,ice and other places
What is the process of fossilisation
-The organism dies
-It gets buried under rock or mud
-The organism does not completely decay
-Minerals replace the hard parts of the organism
-This prevents exposure to oxygen
-this creates a fossil
When do fossils form
-hard parts of the animal or plant are replaced by minerals
-the organism doesn’t decay because it is too cold or it is too dry
-the bacteria that make things decay die because there is not enough oxygen
What is extinction
The permanent loss of all the members of a species
What is the order to classify animals
