Topic 15 - Genetics and Evolution Flashcards
Who was Gregor Mendel?
An Austrian Catholic monk born in 1822.
What did Mendel discover?
By cross breeding different plants, he discovered that characteristics were inherited in clear and predictable patterns.
What did Mendel publish in 1866?
He explained some of the basic laws of genetics using mathematical models in ways we use today.
How did scientists react to Gregor Mendel?
People didn’t understand his work at first and it wasn’t until after his death in 1884 that his work was accepted. By the the late 19th century, people had seen chromosomes through a microscope.
When was DNA shown to be the material of inheritance?
The 1950s
Who pioneered the discovery of DNA?
Maurice Wilkins and Rosalind Franklin in London were looking at the structure of DNA using X-rays. James Watson and Francis Crick at Cambridge. The Cambridge team came up with the double helix using Rosalind Franklin X-ray results were released without by Maurice Wilkins.
What was Jean-Baptiste Lamarck’s theory of evolution?
Evolution by acquired characteristics.
What was Lamarck’s theory of Evolution by acquired characteristics?
If animals used something a lot, he thought that such a feature would grow and develop. He used the example of a Giraffe’s neck.
What was wrong with Lamarck’s theory?
There was no evidence for his view. People could also see that changes to the body, like dying your hair pink, would not be passed down to their offspring.
What did Charles Darwin do in 1831?
He set out on HMS Beagle at 22 years old to discover new things about the natural world. His voyage took him around South America and the South Sea Islands.
How did Darwin build up evidence for his ideas?
Darwin carried out breeding experiments with pigeons. He wanted to show how features could be artificially selected.
What did Charles Darwin do on the 24th of November 1859?
He published his revolutionary ideas in his book ‘On the Origin of Species by Means of Natural Selection’.
Why was Darwin’s theory not initially accepted?
-The theory challenged some views from Christians and other theists that God created life as it is on Earth.
-Many scientists thought there wasn’t enough evidence.
-There was no way to explain how variety and inheritance happened. Genes and inheritance was not fully understood until 50 years after his book was published.
What did Alfred Russel Wallace do?
In 1848 he set off to South America to collect specimens to examine. When he returned home, his collection had been completely destroyed by fire. He then went to a Borneo. He had the idea that if a species existed in several forms, the poorly adapted would die out, leaving the better-adapted. He reached out to Charles Darwin to help publish his findings.
What did Wallace help with discovering?
-The theory of Evolution by natural selection and gathering evidence for the theory.
-Theories on the role of geographic isolation in the formation of species.
What is geographic isolation?
Where populations become separated due to a geographic feature like a mountain range. As a result these organisms evolve in different ways to adapt to their different environment.
How can fossils form?
-Animals or plants do not decay after death. This happens if conditions for decay are not present. This could be due to low oxygen or high poisonous gas concentrations in the area which kills microbes. It could also be due to a too low temperature.
-Many fossils are formed when harder parts of the organism are replaced by minerals as they decay and become rock.
-Some fossils found are not of actual animals or plants but of footprints, burrows or droppings.
Why is the fossil record not complete?
-Many of the earliest life forms were soft-bodied organisms meaning they left little fossil trace. The majority of fossils formed were destroyed by geological activity.
-Most organisms did not become fossilised.
-Many fossils haven’t been found.
